10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 10-Q

x QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2013

or

¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission File Number 000-51470

AtriCure, Inc.

(Exact name of Registrant as specified in its charter)

Delaware	34-1940305
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

6217 Centre Park Drive

West Chester, OH 45069

(Address of principal executive offices)

(513) 755-4100

(Registrant’s telephone number, including area code)

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days:    YES  x    NO  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    YES  x    NO  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer, accelerated filer and smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer	¨	Accelerated Filer	x
Non-Accelerated Filer	¨  (Do not check if a smaller reporting company)	Smaller reporting company	¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act):    YES  ¨    NO  x

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

Class	Outstanding at July 26, 2013
Common Stock, $.001 par value	20,980,093

Table of Contents

	Page
PART I. FINANCIAL INFORMATION
Item 1. Financial Statements
Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012		3
Condensed Consolidated Statements of Operations and Comprehensive Loss for the Three and Six Months Ended June 30, 2013 and 2012		4
Condensed Consolidated Statements of Cash Flows for the Six Months Ended June 30, 2013 and 2012		5
Notes to Condensed Consolidated Financial Statements		6
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations		21
Item 3. Quantitative and Qualitative Disclosures About Market Risk		26
Item 4. Controls and Procedures		26
PART II. OTHER INFORMATION
Item 1. Legal Proceedings		26
Item 1A. Risk Factors		26
Item 6. Exhibits		27
Signatures		28
Exhibit Index		29

2

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

ATRICURE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(In Thousands, Except Per Share Amounts)

(Unaudited)

	June 30, 2013			December 31, 2012
Assets
Current assets:
Cash and cash equivalents	$	31,044		$	7,753
Short-term investments		3,898			4,247
Accounts receivable, less allowance for doubtful accounts of $39 and $49, respectively		11,344			9,948
Inventories		6,028			5,718
Other current assets		1,152			873
Total current assets		53,466			28,539
Property and equipment, net		3,685			3,430
Intangible assets		26			32
Other assets		304			430
Total Assets	$	57,481		$	32,431
Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable	$	5,196		$	5,103
Accrued liabilities		6,176			5,073
Current maturities of long-term debt and capital lease obligations		2,031			2,029
Total current liabilities		13,403			12,205
Long-term debt and capital lease obligations		5,391			6,407
Other liabilities		547			1,319
Total Liabilities		19,341			19,931
Commitments and contingencies (Note 7)
Stockholders’ Equity:
Common stock, $.001 par value, 90,000 shares authorized and 20,980 and 16,896 issued and outstanding, respectively		21			17
Additional paid-in capital		152,660			123,157
Accumulated other comprehensive (loss) income		(56	)		77
Accumulated deficit		(114,485	)		(110,751	)
Total Stockholders’ Equity		38,140			12,500
Total Liabilities and Stockholders’ Equity	$	57,481		$	32,431

See accompanying notes to condensed consolidated financial statements.

3

ATRICURE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(In Thousands, Except Per Share Amounts)

(Unaudited)

	Three Months Ended June 30,						Six Months Ended June 30,
	2013			2012			2013			2012
Revenue	$	20,429		$	18,268		$	39,859		$	35,744
Cost of revenue		5,306			5,557			10,650			10,281
Gross profit		15,123			12,711			29,209			25,463
Operating expenses:
Research and development expenses		3,049			2,885			6,555			6,275
Selling, general and administrative expenses		13,713			11,146			26,093			22,005
Total operating expenses		16,762			14,031			32,648			28,280
Loss from operations		(1,639	)		(1,320	)		(3,439	)		(2,817	)
Other income (expense):
Interest expense		(132	)		(201	)		(305	)		(426	)
Interest income		2			2			6			4
Other		(17	)		199			14			301
Loss before income tax expense		(1,786	)		(1,320	)		(3,724	)		(2,938	)
Income tax expense		5			6			10			8
Net loss	$	(1,791	)	$	(1,326	)	$	(3,734	)	$	(2,946	)
Basic and diluted net loss per share	$	(0.09	)	$	(0.08	)	$	(0.19	)	$	(0.18	)
Weighted average shares outstanding—basic and diluted		20,652			16,132			20,101			16,074
Comprehensive loss:
Unrealized losses on investments		(1	)		(1	)		(1	)		(2	)
Foreign currency translation adjustment		12			(106	)		(132	)		(51	)
Other comprehensive income (loss)		11			(107	)		(133	)		(53	)
Net loss		(1,791	)		(1,326	)		(3,734	)		(2,946	)
Comprehensive loss	$	(1,780	)	$	(1,433	)	$	(3,867	)	$	(2,999	)

See accompanying notes to condensed consolidated financial statements.

4

ATRICURE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(In Thousands)

(Unaudited)

	Six Months Ended June 30,
	2013			2012
Cash flows from operating activities:
Net loss	$	(3,734	)	$	(2,946	)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense		1,338			1,829
Depreciation		951			1,047
Loss (gain) on disposal of equipment		29			(9	)
Amortization of deferred financing costs		46			69
Amortization of intangible assets		6			6
Amortization/accretion on investments		(6	)		19
Change in allowance for doubtful accounts		2			19
Changes in assets and liabilities:
Accounts receivable		(1,463	)		(916	)
Inventories		(320	)		39
Other current assets		(240	)		(176	)
Accounts payable		45			(384	)
Accrued liabilities		375			292
Other non-current assets and non-current liabilities		139			(171	)
Net cash used in operating activities		(2,832	)		(1,282	)
Cash flows from investing activities:
Purchases of property and equipment		(1,191	)		(1,395	)
Purchases of available-for-sale securities		(2,544	)		(6,692	)
Maturities of available-for-sale securities		2,900			4,800
Net proceeds from the sale of equipment		—			24
Net cash used in investing activities		(835	)		(3,263	)
Cash flows from financing activities:
Proceeds from sale of stock, net of offering costs of $212		26,872			—
Proceeds from debt borrowings		—			10,000
Payments on debt and capital leases		(1,014	)		(7,063	)
Payment of debt fees		(98	)		(76	)
Proceeds from issuance of common stock under employee stock purchase plan		326			372
Proceeds from stock option exercises		1,240			434
Shares repurchased for payment of taxes on stock awards		(269	)		(228	)
Net cash provided by financing activities		27,057			3,439
Effect of exchange rate changes on cash and cash equivalents		(99	)		7
Net increase (decrease) in cash and cash equivalents		23,291			(1,099	)
Cash and cash equivalents—beginning of period		7,753			9,759
Cash and cash equivalents—end of period	$	31,044		$	8,660
Supplemental cash flow information:
Cash paid for interest	$	279		$	297
Cash paid for taxes		30			12
Non-cash investing activities:
Accrued purchases of property and equipment		63			23

See accompanying notes to condensed consolidated financial statements.

5

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

1. DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Nature of the Business—AtriCure, Inc. (the “Company” or “AtriCure”) was incorporated in the State of Delaware on October 31, 2000. The Company provides innovative Atrial Fibrillation (“Afib”) solutions designed to produce superior outcomes that reduce the economic and social burden of Afib. The Company sells its products to hospitals globally through a direct sales force and distributors.

Basis of Presentation—The accompanying interim financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”). The accompanying interim financial statements are unaudited, but in the opinion of the Company’s management, contain all of the normal, recurring adjustments considered necessary to present fairly the financial position, results of operations and cash flows for the periods presented in conformity with generally accepted accounting principles generally accepted in the United States (“GAAP”) applicable to interim periods. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted or condensed. The Company believes the disclosures herein are adequate to make the information presented not misleading. Results of operations are not necessarily indicative of the results expected for the full fiscal year or for any future period.

The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012 filed with the SEC.

Principles of Consolidation—The Condensed Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, the Company’s wholly-owned subsidiary organized in the State of Delaware, and AtriCure Europe B.V. (“AtriCure Europe”), the Company’s wholly-owned subsidiary incorporated in the Netherlands. All intercompany accounts and transactions have been eliminated in consolidation.

Cash and Cash Equivalents—The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents.

Investments—The Company places its investments primarily in U.S. Government agencies and securities, corporate bonds and commercial paper. The Company classifies all investments as available-for-sale. Investments with maturities of less than one year are classified as short-term investments. Investments are recorded at fair value, with unrealized gains and losses recorded as accumulated other comprehensive income (loss). The Company recognizes gains and losses when these securities are sold using the specific identification method and includes them in interest income or expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss.

Revenue Recognition—The Company accounts for revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, “Revenue Recognition” (“ASC 605”). The Company determines the timing of revenue recognition based upon factors such as passage of title, payment terms and ability to return products. The Company recognizes revenue when all of the following criteria are met: (i) there is persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured.

Revenue is generated from the sale of the Company’s surgical devices. The Company’s surgical devices consist primarily of individual disposable handpieces and equipment generators. The Company’s customers need the combination of the generator and the handpieces to have a functional system. The Company believes that the generator and handpiece are considered a single unit of accounting under ASC 605 because neither the generator nor handpiece have value to the customer on a standalone basis. Therefore, because the customer needs both the generator and handpiece to have a functional system, revenue is recognized upon the later of delivery of the generator or the handpiece.

Pursuant to the Company’s standard terms of sale, revenue is recognized when title to the goods and risk of loss transfers to customers and there are no remaining obligations that will affect the customers’ final acceptance of the sale. Generally, the Company’s standard terms of sale define the transfer of title and risk of loss to occur upon shipment to the respective customer. The Company generally does not maintain any post-shipping obligations to the recipients of the products. No installation, calibration or testing of this equipment is performed by the Company subsequent to shipment to the customer in order to render it operational.

Revenue includes shipping and handling revenue of $197 and $187 for the three months ended June 30, 2013 and 2012, respectively, and $389 and $377 for the six months ended June 30, 2013 and 2012, respectively. Cost of freight for shipments made to customers is included in cost of revenue. Sales and other value-added taxes collected from customers and remitted to governmental

6

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

authorities are excluded from revenue. The Company sells its products primarily through a direct sales force, with certain international markets sold through distributors. Terms of sale are generally consistent for both end-users and distributors except that payment terms are generally net 30 days for end-users and net 60 days for distributors.

Sales Returns and Allowances—The Company maintains a provision for sales returns and allowances to account for potential returns of defective or damaged products, products shipped in error and price adjustments. The Company estimates such provision quarterly based primarily on a specific identification basis, in addition to estimating a general reserve. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Condensed Consolidated Balance Sheets.

Allowance for Doubtful Accounts Receivable—The Company evaluates the collectability of accounts receivable in order to determine the appropriate reserve for doubtful accounts. In determining the amount of the reserve, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs against the allowance has not been significant.

Inventories—Inventories are stated at the lower of cost or market using the first-in, first-out cost method (“FIFO”) and consist of raw materials, work in process and finished goods. The Company’s industry is characterized by rapid product development and frequent new product introductions. Uncertain timing of product approvals, variability in product launch strategies and variation in product utilization all impact excess and obsolete inventory. An inventory reserve based on product usage is estimated and recorded quarterly for excess, slow moving and obsolete inventory, as well as inventory with a carrying value in excess of its net realizable value. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant.

Inventories consist of the following:

	June 30, 2013		December 31, 2012
Raw materials	$	2,269	$	3,066
Work in process		760		675
Finished goods		2,999		1,977
Inventories	$	6,028	$	5,718

Property and Equipment—Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method of depreciation for financial reporting purposes and applied over the estimated useful lives of the assets. The estimated useful life by major asset category is the following: machinery and equipment is three to seven years, computer and other office equipment is three years, furniture and fixtures is three to seven years and leasehold improvements and equipment leased under a capital lease are the shorter of their useful life or remaining lease term. The Company reassesses the useful lives of property and equipment annually, and assets are retired if they are no longer being used. Maintenance and repair costs are expensed as incurred.

Included in property and equipment are generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) that are loaned at no cost to direct customers that use the Company’s disposable products. These generators are depreciated over a period of one to three years, which approximates their useful lives, and such depreciation is included in cost of revenue. The estimated useful lives of this equipment are based on anticipated usage by our customers and the timing and impact of expected new technology rollouts by the Company. To the extent the Company experiences changes in the usage of this equipment or introductions of new technologies, the estimated useful lives of this equipment may change in a future period. Depreciation related to these generators was $299 and $357 for the three months ended June 30, 2013 and 2012, respectively, and $569 and $673 for the six months ended June 30, 2013 and 2012, respectively. As of June 30, 2013 and December 31, 2012, the net carrying amount of loaned equipment included in net property and equipment in the Condensed Consolidated Balance Sheets was $2,441 and $2,197, respectively.

Impairment of Long-Lived Assets—The Company reviews property and equipment annually for impairment using its best estimates based on reasonable and supportable assumptions and projections.

Intangible Assets—Intangible assets with determinable useful lives are amortized on a straight-line basis over the estimated periods benefited, which range from four to eight years.

7

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

Other Income—Other income consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants which are accounted for as free-standing derivatives. The Company recorded foreign currency transaction gains (losses) of $11 and ($39) for the three months ended June 30, 2013 and 2012, respectively, and $56 and ($35) for the six months ended June 30, 2013 and 2012, respectively, in connection with settlements of its intercompany balance with AtriCure Europe.

The Company periodically is awarded grants to support research and development activities. The Company recognizes grant income when the funds are earned. The Company recorded grant income of $0 and $201 during the three months ended June 30, 2013 and 2012, respectively. Grant income of $0 and $262 was recorded for the six month periods ended June 30, 2013 and 2012, respectively.

The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Because the non-employee options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these options, when vested, are no longer eligible for equity classification and are, thus, subsequently accounted for as derivative liabilities under FASB ASC 815, “Derivatives and Hedging” (“ASC 815”) until the awards are ultimately either exercised or forfeited. Accordingly, the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the three months ended June 30, 2013 and 2012, $28 and ($37), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options. During the six months ended June 30, 2013 and 2012, $42 and ($74), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options.

Taxes—Income taxes are computed using the asset and liability method in accordance with FASB ASC 740, “Income Taxes” (“ASC 740”), under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more likely than not that such assets will not be fully realized. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates.

The Company’s estimate of the valuation allowance for deferred tax assets requires it to make significant estimates and judgments about its future operating results. The Company’s ability to realize the deferred tax assets depends on its future taxable income as well as limitations on their utilization. A deferred tax asset is reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized prior to its expiration. The projections of the Company’s operating results on which the establishment of a valuation allowance is based involve significant estimates regarding future demand for the Company’s products, competitive conditions, product development efforts, approvals of regulatory agencies and product cost. If actual results differ from these projections, or if the Company’s expectations of future results change, it may be necessary to adjust the valuation allowance. In evaluating whether to record a valuation allowance, the applicable accounting standards deem that the existence of cumulative losses in recent years is a significant piece of objectively verifiable negative evidence that must be overcome by objectively verifiable positive evidence to avoid the need to record a valuation allowance. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods.

A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended, (the “Patient Act”) requires manufacturers of medical devices to pay a 2.3% excise tax on all U.S. medical device sales beginning in January 2013. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $128 for the three months ended June 30, 2013 and $248 for the six months ended June 30, 2013.

Net Loss Per Share—Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (“ASC 260”) by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, net loss per share excludes the effect of 2,588 and 2,986 options, restricted stock and performance-based shares as of June 30, 2013 and 2012, respectively, because they are anti-dilutive. Therefore the number of shares calculated for basic net loss per share is also used for the diluted net loss per share calculation.

Comprehensive Loss and Accumulated Other Comprehensive Income (Loss)—In addition to net losses, the comprehensive loss includes foreign currency exchange rate adjustments and unrealized gains and losses on investments.

8

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

Accumulated other comprehensive income (loss) consisted of the following:

	Unrealized Gains on Short- Term Investments			Foreign Currency Translation Adjustment			Accumulated Other Comprehensive Income (Loss)
Balance as of December 31, 2012	$	1		$	76		$	77
Other comprehensive income before reclassifications		0			(189	)		(189	)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			45			45
Net current-period other comprehensive income		0			(144	)		(144	)
Balance as of March 31, 2013	$	1		$	(68	)	$	(67	)
Other comprehensive income before reclassifications		(1	)		1			0
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			11			11
Net current-period other comprehensive income		(1	)		12			11
Balance as of June 30, 2013	$	0		$	(56	)	$	(56	)

Research and Development—Research and development costs are expensed as incurred. These costs include compensation and other internal and external costs associated with the development and research related to new products or concepts, preclinical studies, clinical trials and the cost of products used in trials and tests.

Share-Based Compensation—The Company follows FASB ASC 718, “Compensation-Stock Compensation” (“ASC 718”) to record share-based compensation for all employee share-based payment awards, including stock options, restricted stock, performance shares and stock purchases related to an employee stock purchase plan, based on estimated fair values. The Company’s share-based compensation expense recognized under ASC 718 for the three months ended June 30, 2013 and 2012 was $820 and $1,141, respectively, and $1,338 and $1,829 for the six months ended June 30, 2013 and 2012, respectively, on a before and after tax basis.

FASB ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Condensed Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. FASB ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

The Company estimates the fair value of time-based options on the date of grant using the Black-Scholes option-pricing model (“Black-Scholes model”). The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price, as well as assumptions regarding a number of highly complex and subjective variables. These variables include but are not limited to the Company’s expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. For non-employee options, the fair value at the date of grant is subject to adjustment at each vesting date based upon the fair value of the Company’s common stock. The fair value of market-based performance option grants is estimated at the date of grant using a Monte-Carlo simulation. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in our Condensed Consolidated Statements of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures.

The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company’s determination of fair value is affected by the Company’s stock price as well as assumptions regarding the number of shares expected to be granted.

The Company also has an employee stock purchase plan (“ESPP” or the “Plan”) which is available to all eligible employees as defined by the Plan. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the Plan and records compensation expense based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model.

9

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

The Company has historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. The Company accounts for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50, “Equity-Based Payments to Non-Employees” (“ASC 505-50”). Because these options do not contain specific performance provisions, there is no measurement date of fair value until the options vest. Therefore, the fair value of the options granted and outstanding prior to their vesting date is remeasured each reporting period.

Fully vested options to acquire 38 shares of common stock held by non-employee consultants remained unexercised as of both June 30, 2013 and December 31, 2012. A liability of $120 and $78 was included in accrued liabilities in the Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012, respectively.

Use of Estimates—The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.

Fair Value Disclosures—The book value of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, short-term investments, short and long-term other assets, accounts payable, accrued expenses, other liabilities and fixed interest rate debt, approximate their fair values. The Company classifies cash and short-term investments in U.S. government agencies and securities as Level 1 within the fair value hierarchy. Accounts receivable, short-term other assets, accounts payable and accrued expenses are also classified as Level 1. The carrying amounts of these assets and liabilities approximate their fair value due to their relatively short-term nature. Other assets and other liabilities are classified as Level 1 within the fair value hierarchy. Cash equivalents and short-term investments in commercial paper are classified as Level 2 within the fair value hierarchy (see Note 3 – “Fair Value” for further information). Fixed interest rate debt fair value is determined by calculating the net present value of future debt payments and is classified as Level 2. Significant unobservable inputs with respect to the fair value measurement of the Level 3 non-employee stock options are developed using Company data. When an input is changed, the Black-Scholes model is updated and the results are analyzed for reasonableness.

2. RECENT ACCOUNTING PRONOUNCEMENTS

In February 2013 the FASB issued FASB Accounting Standards Update (“ASU”) 2013-02, “Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income”. This new guidance requires presentation of the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, a cross reference to the related footnote for additional information will be required. This ASU is effective for interim and annual reporting periods beginning after December 15, 2012. The Company has evaluated the provisions of ASU 2013-02 and determined that the new guidance does not have a material impact on the Company’s financial reporting.

In July 2013 the FASB issued FASB ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists”. This new guidance eliminates the diversity in practice for the financial statement presentation of unrecognized tax benefits when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. This ASU is effective for interim and annual reporting periods beginning after December 15, 2013. The Company has evaluated the provisions of ASU 2013-11 and determined that the guidance does not have a material impact on the Company’s financial reporting.

3. FAIR VALUE

FASB ASC 820, “Fair Value Measurements and Disclosures” (“ASC 820”) defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following:

• Level 1—Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. An active market for the asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. The valuation under this approach does not entail a significant degree of judgment.

10

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

• Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The valuation technique for the Company’s Level 2 assets is based on quoted market prices for similar assets from observable pricing sources at the reporting date.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Unobservable inputs shall be used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The fair value of the Company’s Level 3 investments are estimated on the grant date using the Black-Scholes model and they are revalued at the end of each reporting period using the Black-Scholes model.

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of June 30, 2013:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	29,464	$	—	$	29,464
Commercial paper		—		2,898		—		2,898
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	32,362	$	—	$	33,362
Liabilities:
Derivative instruments	$	—	$	—	$	120	$	120
Total liabilities	$	—	$	—	$	120	$	120

There were no changes in the levels of financial assets and liabilities during the three or six month periods ended June 30, 2013.

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2012:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	5,261	$	—	$	5,261
Commercial paper		—		3,247		—		3,247
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	8,508	$	—	$	9,508
Liabilities:
Derivative instruments	$	—	$	—	$	78	$	78
Total liabilities	$	—	$	—	$	78	$	78

The fair value of the Level 3 liabilities is estimated using the Black-Scholes model including the following assumptions:

	As of June 30, 2013	As of December 31, 2012
Risk free interest rate	0.20% – 1.26%	0.23% – 0.74%
Expected life of option (years)	1.25 – 4.61	1.75 – 5.10
Expected volatility of stock	69.00%	70.00%
Dividend yield	0.00%	0.00%

The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Once these non-employee options have vested, the awards no longer fall within the scope of ASC 505-50. Because the options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these vested options are no longer eligible for equity classification and are, thus, accounted for as derivative liabilities under FASB ASC 815 until the awards are ultimately either exercised or forfeited. Accordingly,

11

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. In calculating the fair value of the options, they are estimated on the grant date using the Black-Scholes model subject to change in stock price utilizing assumptions of risk-free interest rate, contractual life of option, expected volatility and dividend yield. Due to the lack of certain observable market quotes, the Company utilizes valuation models that rely on some Level 3 inputs. The Company’s estimate of volatility is based on the Company’s trading history. In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of June 30, 2013:

Beginning Balance–January 1, 2013	$	78
Total gains/losses (realized/unrealized) included in earnings		42
Purchases (exercises)		—
Reclassification from equity to liability when fully vested		—
Ending Balance–June 30, 2013	$	120
Losses included in earnings (or changes in net assets attributable to the change in unrealized gains relating to assets held at reporting date)	$	(42	)

In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of December 31, 2012:

Beginning Balance–January 1, 2012	$	208
Total gains/losses (realized/unrealized) included in earnings		(179	)
Purchases (exercises)		(50	)
Reclassification from equity to liability when fully vested		99
Ending Balance–December 31, 2012	$	78
Gains included in earnings (or changes in net assets attributable to the change in unrealized losses relating to assets held at reporting date)	$	179

4. INTANGIBLE ASSETS

Intangible assets with definite lives are amortized over their estimated useful lives. The following table provides a summary of the Company’s intangible assets with definite lives:

	Non-Compete Agreement
Net carrying amount as of December 31, 2011	$	45
Amortization		(13	)
Net carrying amount as of December 31, 2012		32
Amortization		(6	)
Net carrying amount as of June 30, 2013	$	26

The Company’s amortization term for a non-compete agreement is eight years. Amortization expense related to intangible assets with definite lives was $3 for both the three month periods ended June 30, 2013 and 2012 and $6 for both the six month periods ended June 30, 2013 and 2012.

Estimated future amortization expense related to intangible assets with definite lives is as follows:

Year	Amortization
2013	$	7
2014		12
2015		7
Total	$	26

12

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

5. ACCRUED LIABILITIES

Accrued liabilities consisted of the following:

	June 30, 2013		December 31, 2012
Accrued commissions	$	1,932	$	1,464
Accrued settlement reserve (current portion)		1,364		1,120
Accrued bonus		911		487
Other accrued liabilities		477		707
Accrued vacation		391		349
Accrued taxes and value-added taxes payable		360		366
Accrued payroll		178		153
Accrued royalty		172		118
Withheld payroll taxes		166		126
Accrued non-employee stock options		120		78
Sales/returns allowance—trade		105		105
Total	$	6,176	$	5,073

6. INDEBTEDNESS

The Company has had a debt agreement with Silicon Valley Bank (“SVB”) since May 1, 2009. The agreement, as amended, restated and modified, includes a $10,000 term loan which matures on February 2, 2017 and a $10,000 revolving credit facility which matures on April 30, 2014. The agreement, as amended, restated and modified, contains covenants that include, among others, covenants that limit the Company’s and its subsidiaries’ ability to dispose of assets, enter into mergers or acquisitions, incur indebtedness, incur liens, pay dividends or make distributions on the Company’s capital stock, make investments or loans, and enter into certain affiliate transactions, in each case subject to customary exceptions for a credit facility of this size and type. Additional covenants apply when the Company has outstanding borrowings under the revolving loan facility or when the Company achieves specific covenant milestones. Financial covenants under the credit facility, as amended, include a minimum EBITDA, a limitation on capital expenditures, and a minimum liquidity ratio. Further, a minimum fixed charge ratio applies when the Company achieves specific covenant milestones. None of the specific covenant milestones have been met as of June 30, 2013. The occurrence of an event of default could result in an increase to the applicable interest rate by 3.0%, an acceleration of all obligations under the Agreement, an obligation of the Company to repay all obligations in full and a right by SVB to exercise all remedies available to it under the Agreement and related agreements including the Guaranty and Security Agreement.

Effective January 30, 2013 the Company and SVB entered into a Joinder and Loan Modification Agreement and an Export-Import Bank Joinder and Loan Modification Agreement which set forth certain amendments to the Company’s credit facility with the Bank. These Modification Agreements added the Company’s wholly-owned subsidiary, AtriCure, LLC, as a borrower, and such Loan Modification Agreement modified the Company’s timing for submitting a forecast to the Bank and decreased the EBITDA amount the Company must achieve to meet the minimum EBITDA covenant.

Effective March 29, 2013 the Company and SVB entered into a Loan Modification Agreement and an Export-Import Bank Loan Modification Agreement which set forth certain amendments to the Company’s credit facility with the Bank. These Modification Agreements provide for (i) a change in the applicable borrowing rate on the revolving credit facility from 0.25% to 1.25% above the prime rate based on the Company’s Liquidity Ratio to the prime rate during a Streamline Period and prime plus 1.25% during a Non-Streamline Period, (ii) a reduction in the collateral handling fee on the revolving credit facility, (iii) a reduction in the fixed interest rate on the term loan from 6.75% to 4.75% and (iv) modifications to the Liquidity Ratio and EBITDA financial covenants. The interest rate was 4.75% as of June 30, 2013 and 6.75% as of June 30, 2012.

As of June 30, 2013 the Company had no borrowings under the revolving credit facility and had borrowing availability of approximately $7,957. As of December 31, 2012 the Company had no borrowings under its revolving credit facility and borrowing availability of $5,303. As of June 30, 2013 and December 31, 2012, $7,333 and $8,333, respectively, was outstanding under the term loan, which included $2,000 classified as current maturities of long-term debt. The effective interest rate on borrowings under the modified term loan, including debt issuance costs, was 6.5%. The Company has an outstanding letter of credit of €75 issued to its European subsidiary’s corporate credit card program provider which will expire on June 30, 2015. No letters of credit were outstanding at December 31, 2012. As of and for the period ended June 30, 2013, the Company was in compliance with all of the financial covenants of the amended and modified credit facility. In addition, if the guarantee by the Export-Import Bank of the United States ceases to be in full force and effect, the Company must repay all loans under the Export-Import agreement.

13

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

As of June 30, 2013 the Company had capital leases for computer and office equipment that expire at various terms through 2016, and the cost of the assets under lease was $226. These assets are depreciated over their estimated useful lives, which equal the terms of the leases. Accumulated amortization on the capital leases was $142 at June 30, 2013.

Maturities on long-term debt, including capital lease obligations, are as follows:

2013	$	1,015	July 1, 2013 through December 31, 2013
2014		2,032
2015		2,026
2016		2,016
2017		333
Total	$	7,422

7. COMMITMENTS AND CONTINGENCIES

Operating Leases

The Company leases various types of office, manufacturing and warehouse facilities and equipment under noncancelable operating leases that expire at various terms through 2015.

Royalty Agreements

The Company has certain royalty agreements in place with terms that include payment of royalties based on product revenue from sales of current products. The royalty agreements have effective dates as early as 2003 and terms ranging from three years to at least twenty years. The royalties range from 1.5% to 5% of product sales. One of the agreements includes minimum quarterly payments of $50 through 2015 and a maximum of $2,000 in total royalties over the term of the agreement. Parties to the royalty agreements have the right at any time to terminate the agreement immediately for cause. Royalty expense of $217 and $151 was recorded as part of cost of revenue for the three months ended June 30, 2013 and 2012, respectively, and $539 and $298 for the six months ended June 30, 2013 and 2012, respectively.

Purchase Agreements

On June 15, 2007 the Company entered into a purchase agreement with MicroPace Pty Ltd Inc. (“MicroPace”). The agreement, as amended, provides for MicroPace to produce a derivative of one of their products tailored for the cardiac surgical environment, known as the “MicroPace ORLab^™” for worldwide distribution by the Company. Pursuant to the terms of the amended agreement, in order for the Company to retain exclusive distribution rights, the Company was required to purchase a minimum of 40 units during the period December 1, 2010 through December 31, 2011 to extend exclusivity through 2012 and an additional 40 units during 2012 to extend exclusivity through December 31, 2013. Units purchased in excess of yearly minimums reduce future minimum purchase requirements. A total of 56 units were purchased by the Company between December 1, 2010 and December 31, 2011, thereby extending exclusive distribution rights through December 31, 2012. A total of 60 units were purchased by the Company during 2012, fulfilling the purchase requirement to extend exclusive distribution rights through 2013. The Company purchased 35 units during the first half of 2013.

In April 2012 the Company entered into a development and manufacturing services agreement with Stellartech Research Corporation (“Stellartech”). Under the terms of the agreement, Stellartech will provide development services for the next generation of the Company’s radio frequency generators and will manufacture at least the first 300 units of the product. The agreement also establishes Stellartech as the exclusive supplier of the generators during the three years after product completion. There is no minimum purchase requirement beyond the initial 300 units.

Distributor Termination

In July 2010 the Company terminated a distributor agreement with a European distributor. Under the terms of the agreement the Company paid the distributor a termination fee, repurchased saleable disposable product inventory and assigned the distributor’s capital equipment to AtriCure Europe. Additionally, the Company entered into a consulting agreement with the distributor to provide ongoing consulting services through September 30, 2012. In exchange for these services, beginning October 1, 2010, the distributor earned €50 (approximately $65) per quarter for a total of €400 (approximately $520).

14

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

Legal

The Company is not party to any material pending or threatened litigation, except as described below:

Department of Justice Investigation

In October 2008 the Company received a letter from the Department of Justice (“DOJ”) informing the Company that it was conducting an investigation for potential False Claims Act (“FCA”) and common law violations relating to its surgical ablation devices. Specifically, the letter stated that the DOJ was investigating the Company’s marketing practices utilized in connection with its surgical ablation system to treat Afib, a specific use outside the FDA’s 510(k) clearance. The letter also stated that the DOJ was investigating whether the Company instructed hospitals to bill Medicare for cardiac surgical ablation using incorrect billing codes. The Company cooperated with the investigation and operated its business in the ordinary course during the investigation. In December 2009 the Company reached a tentative settlement with the DOJ to resolve the investigation and recorded a liability and charged operating expenses for a total of $3,956, which represented the net present value of the proposed settlement amount to be paid to the DOJ, the Relator, and Relator’s counsel (total payments based on the settlement inclusive of interest were estimated to be $4,350, payable over five years).

The settlement was finalized pursuant to the preliminary terms in February 2010, and the Company entered into a settlement agreement with the DOJ, the Office of the Inspector General (“OIG”), and the Relator in the qui tam complaint discussed below. The settlement agreement definitively resolved all claims related to the DOJ investigation. The Company did not admit nor will it admit to any wrongdoing in connection with the settlement. As of June 30, 2013 the Company had made $2,575 in payments (including interest), and had a liability related to this settlement totaling $1,736, of which $1,364 was classified as current.

As part of the resolution, the Company also entered into a five year Corporate Integrity Agreement with the OIG. This agreement acknowledges the existence of the Company’s corporate compliance program and provides for certain other compliance-related activities during the five year term of the agreement. Those activities include specific written standards, monitoring, training, education, independent review, disclosure and reporting requirements.

The Company may, from time to time, become a party to additional legal proceedings.

8. INCOME TAX PROVISION

The Company files federal, state, and foreign income tax returns in jurisdictions with varying statutes of limitations. Income taxes are computed using the asset and liability method in accordance with FASB ASC 740 under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more likely than not that such assets will not be fully realized. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates. The Company does not expect any significant unrecognized tax benefits to arise over the next twelve months.

The Company’s provision for income taxes for continuing operations in interim periods is computed by applying its estimated annual effective rate against its loss before income tax (expense) benefit for the period. In addition, non-recurring or discrete items are recorded during the period in which they occur. The effective tax rate for the three months ended June 30, 2013 and 2012 was (0.28%) and (0.44%), respectively. The effective tax rate for the six months ended June 20, 2013 and 2012 was (0.27%) and (0.29%), respectively.

The Company has not accrued interest and penalties related to unrecognized income tax benefits. However, when or if the situation occurs, the Company will recognize interest and penalties within the income tax expense line in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss and within the related tax liability in the Condensed Consolidated Balance Sheets.

9. EQUITY COMPENSATION PLANS

The Company has several share-based incentive plans: the 2001 Stock Option Plan (the “2001 Plan”), the 2005 Equity Incentive Plan (the “2005 Plan”) and the 2008 Employee Stock Purchase Plan (the “ESPP”).

15

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

2001 Plan and 2005 Plan

The 2001 Plan is no longer used for granting incentives. Under the 2005 Plan, the Board of Directors may grant incentive stock options to employees and any parent or subsidiary’s employees, and may grant nonstatutory stock options, restricted stock, stock appreciation rights, performance units or performance shares to employees, directors and consultants of the Company and any parent or subsidiary’s employees, directors and consultants. The administrator (currently the Compensation Committee of the Board of Directors) has the power to determine the terms of any awards, including the exercise price of options, the number of shares subject to each award, the exercisability of the awards and the form of consideration.

Options granted under the 2001 Plan and the 2005 Plan generally expire ten years from the date of grant. Options granted from the 2001 Plan are generally exercisable beginning one year from the date of grant in cumulative yearly amounts of 25% of the shares granted. Options granted from the 2005 Plan generally vest at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter over the following three years. Restricted stock awards granted under the 2005 Plan vest 25% annually over four years from date of grant.

As of June 30, 2013 6,893 shares of common stock had been reserved for issuance under the 2005 Plan. The shares authorized for issuance under the 2005 Plan include: (a) shares reserved but unissued under the 2001 Plan as of August 10, 2005, (b) shares returned to the 2001 Plan as the result of termination of options or the repurchase of shares issued under such plan, and (c) annual increases in the number of shares available for issuance on the first day of each year equal to the lesser of:

• 3.25% of the outstanding shares of common stock on the first day of the fiscal year;

• 825 shares; or

• an amount the Company’s Board of Directors may determine.

On January 1, 2013 an additional 549 shares were authorized for issuance under the 2005 Plan representing 3.25% of the outstanding shares on that date. As of June 30, 2013 there were 1,755 shares available for future grants under the plans.

Activity under the Plans during the six months ended June 30, 2013 was as follows:

Stock Options	Number of Shares Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at January 1, 2013		3,172		$	8.81
Granted		293			8.73
Exercised		(230	)		5.41
Cancelled or forfeited		(904	)		10.34
Outstanding at June 30, 2013		2,331		$	8.54		6.8	$	3,841
Vested and expected to vest		2,186		$	8.62		6.6	$	3,520
Exercisable at June 30, 2013		1,228		$	9.42		4.5	$	1,508

Restricted Stock	Number of Shares Outstanding			Weighted Average Grant Date Fair Value
Outstanding at January 1, 2013		504		$	7.93
Granted		20			8.92
Released		(84	)		9.44
Forfeited		(183	)		8.21
Outstanding at June 30, 2013		257		$	7.31

The total intrinsic value of options exercised during the three month periods ended June 30, 2013 and 2012 was $135 and $1,093, respectively. The total intrinsic value of options exercised during the six month periods ended June 30, 2013 and 2012 was $599 and $1,244, respectively. As a result of the Company’s tax position, no tax benefit was recognized related to the stock option exercises. For the six month periods ended June 30, 2013 and 2012, respectively, $1,240 and $434 in cash proceeds was included in

16

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

the Company’s Condensed Consolidated Statements of Cash Flows as a result of the exercise of stock options. The total fair value of performance shares vested during both of the three month periods ended June 30, 2013 and 2012 was $0, and the total fair value of performance shares vested during the six month periods ended June 30, 2013 and 2012 was $0 and $99, respectively. The total fair value of restricted stock vested during the three month periods ended June 30, 2013 and 2012 was $98 and $114, respectively. The total fair value of restricted stock vested during the six month periods ended June 30, 2013 and 2012 was $705 and $724, respectively.

The exercise price per share of each option is equal to the fair market value of the underlying share on the date of grant. The Company issues registered shares of common stock to satisfy stock option exercises and restricted stock grants.

The Company recognized expense related to stock options and restricted stock for the three months ended June 30, 2013 and 2012 of $747 and $1,087, respectively. The Company recognized expense related to stock options and restricted stock for the six months ended June 30, 2013 and 2012 of $1,206 and $1,677, respectively. Incremental compensation expense of $396 was recorded during the second quarter of 2012 due to the modification of share-based compensation of the Company’s former Chief Financial Officer. As of June 30, 2013 there was $8,942 of unrecognized compensation costs related to non-vested stock option and restricted stock arrangements ($6,032 relating to stock options and $2,910 relating to restricted stock). This cost is expected to be recognized over a weighted average period of 3.2 years for stock options and 2.9 years for restricted stock.

The Company awarded 225 performance options to its new President and Chief Executive Officer when he joined the Company in November 2012. The options expire ten years from the date of grant and vest in increments of 25 shares when the volume adjusted weighted average closing price of the common stock of the Company as reported by NASDAQ (or any other exchange on which the common stock of the Company is listed) for 30 consecutive days equals or exceeds each of $10.00 per share, $12.50 per share, $15.00 per share, $17.50 per share, $20.00 per share, $25.00 per share, $30.00 per share, $35.00 per share and $40.00 per share. In accordance with FASB ASC 718, a Monte Carlo simulation was performed to estimate the fair values, vesting terms and vesting probabilities for each tranche of options. Expense calculated using these estimates is being recorded over the estimated vesting terms. The Company recognized expense of $45 related to the performance options during the three months ended June 30, 2013. The Company recognized expense of $83 related to the performance options during the six months ended June 30, 2013. As of June 30, 2013 there was $549 of unrecognized compensation costs related to non-vested performance options. The cost is expected to be recognized over a weighted-average period of 2.45 to 5.22 years. None of the market conditions were met as of June 30, 2013; therefore, none of the performance options were exercisable.

The Company historically issued performance shares to certain employees and consultants to incent and reward them for the achievement of specified performance over various service periods. The participants receive awards for a specified number of shares of the Company’s common stock at the beginning of the award period, which entitles the participants to the shares at the end of the award period if achievement of the specified metrics and service requirements occurs. The Company did not release any performance shares (gross) during the three months ended June 30, 2013 and 2012 related to the participants’ achievement of certain specified metrics. The Company released 0 and 10 performance shares (gross) during the six months ended June 30, 2013 and 2012, respectively, related to the participants’ achievement of certain specified metrics. As of June 30, 2013 the Company has no performance shares outstanding. In accordance with FASB ASC 718, the Company estimates the number of shares to be granted based upon the probability that the performance metric and service period will be achieved. The fair value of the estimated award, based on the market value of the Company’s stock on the date of award, is expensed over the award period. The probability of meeting the specified metrics is reviewed quarterly. The Company recognized no expense related to performance shares during the three months ended June 30, 2013 and 2012 or the six months ended June 30, 2013 and 2012. As of June 30, 2013 there was no unrecognized compensation cost related to non-vested share-based compensation arrangements associated with performance shares.

Employee Stock Purchase Plan (ESPP)

During 2008 the Company established its 2008 Employee Stock Purchase Plan (“ESPP”) which is available to eligible employees as defined in the ESPP. Under the ESPP, shares of the Company’s common stock may be purchased at a discount (currently 15%) of the lesser of the closing price of the Company’s common stock on the first trading day or the last trading day of the offering period. The offering period (currently six months) and the offering price are subject to change. Participants may not purchase more than $25 of the Company’s common stock in a calendar year and, effective January 1, 2009, may not purchase more than 1.5 shares during an offering period. Beginning on January 1, 2009 and on the first day of each fiscal year thereafter during the term of the ESPP, the number of shares available for sale under the ESPP shall be increased by the lesser of (i) two percent (2%) of the Company’s outstanding shares of common stock as of the close of business on the last business day of the prior calendar year, not to exceed 600 shares, or (ii) a lesser amount determined by the Board of Directors. At June 30, 2013 there were 720 shares available for future issuance under the ESPP. Share-based compensation expense with respect to the ESPP was $73 and $54 for the three months ended June 30, 2013 and 2012, respectively. Share-based compensation expense with respect to the ESPP was $132 and $152 for the six months ended June 30, 2013 and 2012, respectively.

17

ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

Valuation and Expense Information Under FASB ASC 718

The following table summarizes share-based compensation expense related to employee share-based compensation under FASB ASC 718 for the three and six months ended June 30, 2013 and 2012. This expense was allocated as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Cost of revenue	$	69	$	68	$	127	$	134
Research and development expenses		59		92		100		132
Selling, general and administrative expenses		692		981		1,111		1,563
Total share-based compensation expense related to employees	$	820	$	1,141	$	1,338	$	1,829

In calculating compensation expense, the fair value of the options is estimated on the grant date using the Black-Scholes model including the following assumptions:

	Three Months Ended June 30,		Six Months Ended June 30,
	2013	2012	2013	2012
Risk free interest rate	0.75%–1.38%	1.16%–1.21%	0.75%–1.51%	0.85%–1.37%
Expected life of option (years)	5.33–6.91	6.85–7.06	5.31–7.38	5.39–7.14
Expected volatility of stock	69.00%	71.00%	69.00%	71.00%
Weighted-average volatility	69.00%	71.00%	69.00%	71.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%

The Company’s estimate of volatility is based solely on the Company’s trading history. The risk-free interest rate assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life. The Company estimates the expected terms of options using historical employee exercise behavior adjusted for abnormal activity.

The fair value of restricted stock awards is based on the market value of the Company’s stock on the date of the awards.

Based on the assumptions noted above, the weighted average estimated fair value per share of the stock options and restricted stock granted for the respective periods was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Stock options	$	5.52	$	5.34	$	5.50	$	6.20
Restricted stock		8.92		8.21		8.92		9.86

In calculating compensation expense for performance options, the fair value of the options was estimated on the grant date using a Monte Carlo simulation including the following assumptions:

Strike price	$	5.91
Contractual term		10.00
Expected volatility of stock		69.60	%
Expected rate of return		1.75	%
Dividend yield		0.00	%

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ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

The contractual term is estimated considering that the performance options were issued to a high ranking executive of the Company and that they will be held until expiration. Expected volatility is estimated based on the Company’s trading history. The expected rate of return assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life.

Based on the assumptions noted above, the estimated grant date fair value per share of the performance options granted in 2012 was as follows:

	Price Target		Fair Value
Tranche 1	$	10.00	$	4.32
Tranche 2		12.50		4.30
Tranche 3		15.00		4.27
Tranche 4		17.50		4.23
Tranche 5		20.00		4.19
Tranche 6		25.00		4.10
Tranche 7		30.00		4.01
Tranche 8		35.00		3.92
Tranche 9		40.00		3.83

Non-Employee Stock Compensation

The Company historically issued nonstatutory common stock options to consultants to purchase shares of common stock as a form of compensation for services provided to the Company. Such options vest over a service period ranging from immediately to four years. After January 1, 2006 all stock options granted to non-employee consultants have a four year vesting period and vest at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter.

The Company accounts for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50. Because these options do not contain specific performance provisions, there is no measurement date of fair value until the options vest. Therefore, the fair value of the options granted and outstanding prior to their vesting date is remeasured each reporting period. The fair value was determined using the Black-Scholes model. No non-employee stock options have been granted since 2008. The values attributable to the non-vested portion of the non-employee stock options have been amortized over the service period on a graded vesting method and the vested portion of these stock options was remeasured at each vesting date. As of June 30, 2013 all non-employee consultant options were fully vested.

Once these non-employee consultant stock options have vested, the awards no longer fall within the scope of ASC 505-50. Because the stock options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the stock options to be partially net-cash settled, these vested stock options are no longer eligible for equity classification and are, thus, accounted for as derivative liabilities under FASB ASC 815 until the stock options are ultimately either exercised or forfeited. Accordingly, the vested non-employee consultant stock options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the three months ended June 30, 2013 and 2012, $28 and ($37), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these stock options. During the six months ended June 30, 2013 and 2012, $42 and ($74), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these stock options. As of both June 30, 2013 and December 31, 2012, fully vested stock options to acquire 38 shares of common stock held by non-employee consultants remained unexercised and a liability of $120 and $78 was included in accrued liabilities in the Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012, respectively.

10. SEGMENT AND GEOGRAPHIC INFORMATION

The Company considers reporting segments in accordance with FASB ASC 280, “Segment Reporting”. The Company develops, manufactures, and sells devices designed primarily for the surgical ablation of cardiac tissue and systems designed for the exclusion of the left atrial appendage. These devices are developed and marketed to a broad base of medical centers in the United States and internationally. Management considers all such sales to be part of a single reportable segment.

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ATRICURE, INC. AND SUBSIDIARIES

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except per share amounts)

(Unaudited)

Geographic revenue was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
United States	$	15,454	$	13,411	$	30,093	$	26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

Revenue by product type was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
Revenue:	2013		2012		2013		2012
Open-heart	$	9,154	$	8,386	$	18,275	$	16,873
Minimally Invasive		3,511		3,264		6,643		6,212
AtriClip		2,789		1,761		5,175		3,520
Total United States		15,454		13,411		30,093		26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

The majority of the Company’s long-lived assets are located in the United States.

11. PUBLIC OFFERING OF COMMON STOCK

In January 2013 the Company completed a public offering of common stock under its July 2011 shelf registration. The Company sold 3,996 shares of common stock, par value $0.001 per share, at a price of $7.25 per share, generating proceeds of $26,872 after expenses. Offering costs were recorded in additional paid in capital to offset proceeds. The Company intends to use the proceeds from the offering for general corporate purposes and working capital.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

(Dollar amounts referenced in this Item 2 are in thousands, except per share amounts.)

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with the accompanying Condensed Consolidated Financial Statements and notes thereto contained in Item 1 of Part I of this Form 10-Q and our audited financial statements and notes thereto as of and for the year ended December 31, 2012 included in our Form 10-K filed with the Securities and Exchange Commission (“SEC”) to provide an understanding of our results of operations, financial condition and cash flows.

Forward-Looking Statements

This Form 10-Q, including the sections titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Risk Factors,” contains forward-looking statements regarding our future performance. All forward-looking information is inherently uncertain and actual results may differ materially from assumptions, estimates or expectations reflected or contained in the forward-looking statements as a result of various factors, including those set forth under “Risk Factors” and elsewhere in this quarterly report on Form 10-Q, and in our annual report on Form 10-K for the year ended December 31, 2012. Forward-looking statements convey our current expectations or forecasts of future events. All statements contained in this Form 10-Q other than statements of historical fact are forward-looking statements. Forward-looking statements include statements regarding our future financial position, business strategy, budgets, projected costs, plans and objectives of management for future operations. The words “may,” “continue,” “estimate,” “intend,” “plan,” “will,” “believe,” “project,” “expect,” “anticipate” and similar expressions may identify forward-looking statements, but the absence of these words does not necessarily mean that a statement is not forward-looking. With respect to the forward-looking statements, we claim the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. These forward-looking statements speak only as of the date of this Form 10-Q. We undertake no obligation to publicly update or revise any forward-looking statements to reflect new information or future events or otherwise unless required by law.

Overview

We are a medical device company providing innovative Atrial Fibrillation (“Afib”) solutions designed to produce superior outcomes that reduce the economic and social burden of Afib. Our Synergy Ablation System (“Synergy System”) is the first and only device approved by the United States Food and Drug Administration (“FDA”) for the treatment of persistent and long-standing persistent forms of Afib in patients undergoing certain open concomitant procedures. We have two primary product lines for the ablation of cardiac tissue. Our primary product line for the ablation of cardiac tissue is our Synergy System, a bipolar ablation clamp system and related radiofrequency (“RF”) ablation devices. We also offer a cryoablation product line, which features reusable and disposable cryoablation devices. Additionally, we offer the AtriClip™ Gillinov-Cosgrove Left Atrial Appendage System (“AtriClip system”), which is designed to safely and effectively exclude the left atrial appendage.

Cardiothoracic surgeons have adopted our RF ablation and cryoablation systems to treat Afib in an estimated 138,000 patients since January 2003, and we believe that we are currently the market leader in the surgical treatment of Afib. Our products are utilized by cardiothoracic surgeons during concomitant open-heart surgical procedures and also during sole-therapy minimally invasive cardiac ablation procedures. During a concomitant open procedure, the surgeon ablates cardiac tissue and/or excludes the left atrial appendage, secondary, or concomitant, to a primary cardiac procedure such as a valve or coronary bypass. Additionally, although our products are not FDA-approved for this specific use, cardiothoracic surgeons have adopted our products as a treatment alternative for Afib patients who may be candidates for sole-therapy minimally invasive surgical procedures. Our Synergy System, which includes our Isolator^® Synergy clamps, an RF generator and related switchbox, is approved by the FDA for the treatment of patients with persistent and long-standing persistent Afib during open-heart concomitant coronary artery bypass grafting and/or valve replacement or repair procedures. To date, none of our other products have been approved or cleared by the FDA for the treatment of other forms of Afib or for other uses for the treatment of Afib. Additionally, the FDA has not cleared or approved our products for a reduction in the risk of stroke. We anticipate that substantially all of our revenue for the foreseeable future will relate to products we currently sell, or are in the process of developing, which surgeons generally use to ablate cardiac tissue for the treatment of Afib or for the exclusion of the left atrial appendage.

Recent Developments

The December 2011 FDA approval of our Synergy System included the requirement to implement a 350-patient post-approval study (“PAS”). The trial is designed to evaluate the long-term treatment effect of our Synergy Ablation System in persistent and long-standing persistent Afib patients undergoing open-heart procedures. We submitted a protocol for the PAS to the FDA in February 2012, and it was approved in September 2012. Approximately 153 patients have been enrolled in the trial. The approval also included the requirement to implement a physician training and education program for existing and new users. Approximately 911 physicians at 647 hospitals have been certified through the education program.

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We are also conducting a Staged DEEP clinical trial. The Staged DEEP AF trial protocol was submitted to the FDA in February 2012. The trial evaluates the effectiveness of a staged approach, where a minimally invasive ablation procedure is performed initially and the catheter and mapping optimization procedure is performed on a different day during the same hospitalization. Final FDA approval was received in June 2012. Enrollment in the Staged DEEP trial was initiated during the third quarter of 2012, and there are currently 25 patients enrolled. We expect to enroll up to 30 patients at six medical centers during the course of the trial.

A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended, (the “Patient Act”) requires manufacturers of medical devices to pay a 2.3% excise tax on all U.S. medical device sales beginning in January 2013. We recorded $128 related to the medical device excise tax in cost of revenue during the three months ended June 30, 2013 and $248 during the six months ended June 30, 2013.

In January 2013 we completed a public offering of common stock under our July 2011 shelf registration. We sold 3,996 shares of common stock, par value $0.001 per share, at a price of $7.25 per share to generate proceeds of $26,872 after expenses. Offering costs were recorded in additional paid in capital to offset proceeds. We plan to use the proceeds from the offering for general corporate purposes and working capital.

Results of Operations

Three months ended June 30, 2013 compared to three months ended June 30, 2012

The following table sets forth, for the periods indicated, our results of operations expressed as dollar amounts and as percentages of total revenue:

	Three Months Ended June 30,
	2013						2012
	Amount			% of Revenues			Amount			% of Revenues
Revenue	$	20,429			100.0	%	$	18,268			100.0	%
Cost of revenue		5,306			26.0	%		5,557			30.4	%
Gross profit		15,123			74.0	%		12,711			69.6	%
Operating expenses:
Research and development expenses		3,049			14.9	%		2,885			15.8	%
Selling, general and administrative expenses		13,713			67.1	%		11,146			61.0	%
Total operating expenses		16,762			82.1	%		14,031			76.8	%
Loss from operations		(1,639	)		(8.0	%)		(1,320	)		(7.2	%)
Other income (expense):
Interest expense		(132	)		(0.6	%)		(201	)		(1.1	%)
Interest income		2			0.0	%		2			0.0	%
Other		(17	)		(0.1	%)		199			1.1	%
Total other income (expense)		(147	)		(0.7	%)		(0	)		(0.0	%)
Loss before income tax expense		(1,786	)		(8.7	%)		(1,320	)		(7.2	%)
Income tax expense		5			0.0	%		6			0.0	%
Net loss	$	(1,791	)		(8.7	%)	$	(1,326	)		(7.2	%)

Revenue. Total revenue increased 11.8% (11.5% on a constant currency basis) from $18,268 for the three months ended June 30, 2012 to $20,429 for the three months ended June 30, 2013. Revenue from sales to customers in the United States increased $2,043 million, or 15.2%, and revenue from sales to international customers increased $118, or 2.4% (1.1% on a constant currency basis). The increase in sales to customers in the United States was primarily due to increased sales of ablation-related open-heart products of $768 and increased sales of the AtriClip system of $1,028. The increase in international revenue was primarily due to an increase in sales to direct customers and certain distributors.

Cost of revenue and gross margin. Cost of revenue decreased $251, from $5,557 for the three months ended June 30, 2012 to $5,306 for the three months ended June 30, 2013. As a percentage of revenue, cost of revenue decreased from 30.4% for the three months ended June 30, 2012 to 26.0% for the three months ended June 30, 2013. Gross margin for the three months ended June 30, 2013 and 2012 was 74.0% and 69.6%, respectively. The increase in gross margin was primarily due to volume-driven leverage of manufacturing overhead expenses, a higher mix of domestic sales and the strong performance of our new AtriClip Pro product.

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Research and development expenses. Research and development expenses increased $164, from $2,885 for the three months ended June 30, 2012 to $3,049 for the three months ended June 30, 2013. The increase in expense was primarily due to a $488 increase in product development project and personnel expense and a $134 increase in clinical trial spending, offset by a $401 decrease in clinical affairs consulting.

Selling, general and administrative expenses. Selling, general and administrative expenses increased $2,567, or 23.0%, from $11,146 for the three months ended June 30, 2012 to $13,713 for the three months ended June 30, 2013. The increase was primarily due to an increase in sales and marketing expenditures and an increase in training related to the FDA clearance of our Synergy System for the treatment of Afib.

Net interest expense. Net interest expense for the three months ended June 30, 2013 and 2012 was $130 and $199, respectively. Net interest expense primarily represents interest expense related to amounts outstanding on our term loan and amortization of debt issuance costs.

Other income and expense. Other income and expense consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants, which are accounted for as free-standing derivatives. Other (expense) income for the three months ended June 30, 2013 and 2012 totaled ($17) and $199, respectively.

Six months ended June 30, 2013 compared to six months ended June 30, 2012

The following table sets forth, for the periods indicated, our results of operations expressed as dollar amounts and as percentages of total revenue:

	Six Months Ended June 30,
	2013						2012
	Amount			% of Revenues			Amount			% of Revenues
Revenue	$	39,859			100.0	%	$	35,744			100.0	%
Cost of revenue		10,650			26.7	%		10,281			28.8	%
Gross profit		29,209			73.3	%		25,463			71.2	%
Operating expenses:
Research and development expenses		6,555			16.4	%		6,275			17.6	%
Selling, general and administrative expenses		26,093			65.5	%		22,005			61.6	%
Total operating expenses		32,648			81.9	%		28,280			79.1	%
Loss from operations		(3,439	)		(8.6	%)		(2,817	)		(7.9	%)
Other income (expense):
Interest expense		(305	)		(0.8	%)		(426	)		(1.2	%)
Interest income		6			0.0	%		4			0.0	%
Other		14			0.0	%		301			0.9	%
Total other income (expense)		(285	)		(0.8	%)		(121	)		(0.3	%)
Loss before income tax expense		(3,724	)		(9.4	%)		(2,938	)		(8.2	%)
Income tax expense		10			0.0	%		8			0.0	%
Net loss	$	(3,734	)		(9.4	%)	$	(2,946	)		(8.2	%)

Revenue. Total revenue increased 11.5% (11.3% on a constant currency basis) from $35,744 for the six months ended June 30, 2012 to $39,859 for the six months ended June 30, 2013. Revenue from sales to customers in the United States increased $3,488, or 13.1%, and revenue from sales to international customers increased $627, or 6.9% (6.1% on a constant currency basis). The increase in sales to customers in the United States was primarily due to increased sales of ablation-related open-heart products of $1,402 and increased sales of the AtriClip system of $1,655. The increase in international revenue was primarily due to an increase in sales to direct customers and certain distributors.

Cost of revenue and gross margin. Cost of revenue increased $369, from $10,281 for the six months ended June 30, 2012 to $10,650 for the six months ended June 30, 2013. As a percentage of revenue, cost of revenue decreased from 28.8% for the six months ended June 30, 2012 to 26.7% for the six months ended June 30, 2013. Gross margin for the six months ended June 30, 2013 and 2012 was 73.3% and 71.2%, respectively. The increase in gross margin was primarily due to volume-driven leverage of manufacturing overhead expenses, a higher mix of domestic sales, lower sales of capital equipment and the strong performance of our new AtriClip Pro product.

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Research and development expenses. Research and development expenses increased $280, from $6,275 for the six months ended June 30, 2012 to $6,555 for the six months ended June 30, 2013. The increase in expense was primarily due to a $643 increase in product development project and personnel expense and a $192 increase in clinical trial spending, offset by a $615 decrease in clinical affairs consulting.

Selling, general and administrative expenses. Selling, general and administrative expenses increased $4,088, or 18.6%, from $22,005 for the six months ended June 30, 2012 to $26,093 for the six months ended June 30, 2013. The increase was primarily due to an increase in sales and marketing expenditures and an increase in training related to the FDA clearance of our Synergy System for the treatment of Afib.

Net interest expense. Net interest expense for the six months ended June 30, 2013 and 2012 was $299 and $422, respectively. Net interest expense primarily represents interest expense related to amounts outstanding on our term loan and amortization of debt issuance costs.

Other income and expense. Other income and expense consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants, which are accounted for as free-standing derivatives. Other income for the six months ended June 30, 2013 and 2012 totaled $14 and $301, respectively.

Liquidity and Capital Resources

As of June 30, 2013 the Company had cash, cash equivalents and investments of $34,942 and short-term and long-term debt of $7,333, resulting in a net cash position of $27,609. We had unused borrowing capacity of approximately $7,957 under our revolving credit facility. We had net working capital of $40,063 and an accumulated deficit of $114,485 as of June 30, 2013.

Cash flows used in operating activities. Net cash used in operating activities for the six months ended June 30, 2013 was $2,832. The primary net uses of cash for operating activities were as follows:

• the net loss of $3,734, offset by $2,366 of non-cash expenses, including $1,338 in share-based compensation and $957 in depreciation and amortization; and

• a net increase in cash used related to changes in operating assets and liabilities of $1,464, due primarily to the following:

• an increase in accounts receivable of $1,463, due primarily to an increase in sales during the first half of 2013 as compared to the first half of 2012; and

• a $420 increase in accounts payable and accrued liabilities due primarily to the timing of payments.

Cash flows used in investing activities. Net cash used in investing activities was $835 for the six months ended June 30, 2013. The primary net uses of cash for investing activities were:

• a use of cash of $1,191 related to the purchase of equipment, which consisted primarily of the placement of our RF and cryo generators with our customers; and

• net investment maturities of $356.

Cash flows provided by financing activities. Net cash provided by financing activities during the six months ended June 30, 2013 was $27,057, which was primarily due to proceeds from the sale of stock of $26,872 and proceeds from stock option exercises of $1,240, partially offset by shares repurchased for payment of taxes on stock awards of $269 and debt payments of $1,014.

Credit facility. The Company’s Loan and Security Agreement with Silicon Valley Bank (“SVB”), as amended, restated, and modified (the “Agreement”) provides for a term loan and a revolving credit facility under which we could borrow a maximum of $20,000. As of June 30, 2013 we had no borrowings under the revolving credit facility, and we had borrowing availability of approximately $7,957. The applicable borrowing rate on the revolving facility is the prime rate during a Streamline Period and prime plus 1.25% during a Non-Streamline Period, and the revolving credit facility expires on April 30, 2014. Also, as of June 30, 2013, $7,333 was outstanding under the term loan, which included $2,000 classified as current maturities of long-term debt. The term loan has a five year term, and principal payments in the amount of $167, together with accrued interest, are due and payable monthly. The term loan accrues interest at a fixed rate of 4.75% and matures in February 2017.

The Agreement contains covenants that include, among others, covenants that limit our ability to dispose of assets, enter into mergers or acquisitions, incur indebtedness, incur liens, pay dividends or make distributions on our capital stock, make investments or loans, and enter into certain affiliate transactions, in each case subject to customary exceptions for a credit facility of this size and type. Additional covenants apply when we have outstanding borrowings under the revolving loan facility or when we achieve specific covenant milestones. Financial covenants include a limitation on capital expenditures and a minimum liquidity ratio. Further, a minimum fixed charge ratio and a minimum EBITDA apply when specific events occur. The occurrence of an event of default could

24

result in an increase to the applicable interest rate by 3.0%, an acceleration of all obligations under the Agreement, an obligation to repay all obligations in full, and a right by SVB to exercise all remedies available to it under the Agreement and related agreements including the Guaranty and Security Agreement. As of and for the period ended June 30, 2013 we were in compliance with all of the financial covenants of our amended and modified credit facility. In addition, if the guarantee by the Export-Import Bank of the United States ceases to be in full force and effect, we must repay all loans under the Export-Import agreement.

The effective interest rate on borrowings under the modified term loan, including debt issuance costs, is 6.5%. We have an outstanding letter of credit of €75 issued to our European subsidiary’s corporate credit card provider which will expire on June 30, 2015.

Uses of liquidity and capital resources. Our future capital requirements depend on a number of factors, including the rate of market acceptance of our current and future products, the resources we devote to developing and supporting our products, future expenses to expand and support our sales and marketing efforts, costs relating to changes in regulatory policies or laws that affect our operations and costs of filing, costs associated with clinical trials and securing regulatory approval for new products, costs associated with prosecuting, defending and enforcing our intellectual property rights and possible acquisitions and joint ventures. Global economic turmoil may adversely impact our revenue, access to the capital markets or future demand for our products.

In July 2011 we filed a shelf registration statement with the SEC, which allows us to sell any combination of senior or subordinated debt securities, common stock, preferred stock, warrants, depositary shares and units in one or more offerings should we choose to do so in the future. In January 2013 we sold approximately 3,996 shares of common stock under the shelf registration which resulted in net proceeds of approximately $26,872.

We believe that our current cash, cash equivalents and investments, along with the cash we expect to generate or use for operations or access via our revolving credit facility, will be sufficient to meet our anticipated cash needs for working capital and capital expenditures for at least the next twelve months. Significant cash needs over the next twelve months include debt service of approximately $2,309 ($167 per month plus interest) on our outstanding term loan and payments under our settlement agreement with the DOJ and Relator of $1,400. If our sources of cash are insufficient to satisfy our liquidity requirements, we may seek to sell additional equity or debt securities or obtain a revised or additional credit facility. The sale of additional equity or convertible debt securities could result in dilution to our stockholders. If additional funds are raised through the issuance of debt securities, these securities could have rights senior to those associated with our common stock and could contain covenants that would restrict our operations. Additional financing may not be available at all, or in amounts or terms acceptable to us. Finally, our credit facilities require compliance with certain financial and other covenants. In the event we cannot or do not comply with such covenants, our debt may be callable and become currently due. If we are unable to obtain this additional financing, we may be required to reduce the scope of our planned research and development, clinical activities and selling and marketing efforts.

Off-Balance-Sheet Arrangements

As of June 30, 2013 we had operating lease agreements not recorded on the Condensed Consolidated Balance Sheets. Operating leases are utilized in the normal course of business.

Seasonality

During the third quarter, we typically experience a decline in revenue that we attribute primarily to the elective nature of the procedures in which our products are used, which we believe arises from fewer people choosing to undergo elective procedures during the summer months.

Critical Accounting Policies and Estimates

Our discussion and analysis of our financial condition and results of operations is based upon our financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of financial statements requires management to make estimates and judgments that affect the reported amounts of assets and liabilities, revenue and expenses, and disclosures of contingent assets and liabilities at the date of the financial statements. On a periodic basis, we evaluate our estimates, including those related to sales returns and allowances, accounts receivable, inventories and share-based compensation. We use authoritative pronouncements, historical experience and other assumptions as the basis for making estimates. Actual results could differ from those estimates under different assumptions or conditions. Our Annual Report on Form 10-K for the fiscal year ended December 31, 2012 includes additional information about the Company, our operations, our financial position, our critical accounting policies and accounting estimates and should be read in conjunction with this Quarterly Report.

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Recent Accounting Pronouncements

See Note 2 in the Notes to the Condensed Consolidated Financial Statements for a discussion of recent accounting pronouncements.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

As of June 30, 2013 there were no material changes to the information provided under Item 7A-Quantitative and Qualitative Disclosures About Market Risk in the Company’s Form 10-K for the year ended December 31, 2012.

Item 4. Controls and Procedures

Disclosure Controls and Procedures

We have evaluated the effectiveness of the design and operation of our disclosure controls and procedures, as defined in Rules 13(a)-15(e) and 15(d)-15(e) of the Securities Exchange Act of 1934 (the “Exchange Act”), as of the end of the period covered by this report. Our management, including the President and Chief Executive Officer (the Principal Executive Officer) and Vice President and Chief Financial Officer (the Principal Accounting and Financial Officer), supervised and participated in the evaluation. Based on the evaluation, we concluded that, as of the end of the period covered by this report, our disclosure controls and procedures were effective in providing reasonable assurance that information required to be disclosed by us in the reports we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s forms and rules, and the material information relating to the Company is accumulated and communicated to management, including the President and Chief Executive Officer (the Principal Executive Officer) and Vice President and Chief Financial Officer (the Principal Accounting and Financial Officer), as appropriate, to allow timely decisions regarding required disclosures.

Control systems, no matter how well designed and operated, can provide only reasonable, not absolute, assurance that control objectives are met. Because of inherent limitations in all control systems, no evaluation of controls can provide assurance that all control issues and instances of fraud, if any, within a company will be detected. Additionally, controls can be circumvented by individuals, by collusion of two or more people, or by management override. Over time, controls can become inadequate because of changes in conditions or the degree of compliance may deteriorate. Further, the design of any system of controls is based in part upon assumptions about the likelihood of future events. There can be no assurance that any design will succeed in achieving its stated goals under all future conditions. Because of the inherent limitations in any cost-effective control system, misstatements due to errors or fraud may occur and not be detected.

Changes in Internal Control Over Financial Reporting

In the ordinary course of business we routinely enhance our information systems by either upgrading current systems or implementing new ones. There were no changes in our internal control over financial reporting that occurred during the three months ended June 30, 2013 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

PART II. OTHER INFORMATION

Item 1. Legal Proceedings

Information with respect to legal proceedings can be found under the heading “Legal” in Note 7, “Commitments and Contingencies” to the Condensed Consolidated Financial Statements in Part I, Item 1 of this Quarterly Report on Form 10-Q, and is incorporated herein by reference.

Item 1A. Risk Factors

In addition to the other information set forth in this report, careful consideration should be given to the factors discussed in Part I, “Item 1A. Risk Factors” in our Form 10-K for the year ended December 31, 2012, all of which could materially affect our business, financial condition or future results. The risks described are not the only risks facing us. Additional risks and uncertainties not currently known to us, or that we currently deem to be immaterial, also may adversely affect our business, financial condition and/or operating results. There have been no material changes with respect to the risk factors disclosed in our Annual Report on Form 10-K for the year ended December 31, 2012.

26

Item 6. Exhibits

Exhibit No.	Description
10.1#	Amendment No. 1 to Employment Agreement, dated as of May 24, 2013, between AtriCure, Inc. and Michael H. Carrel
31.1	Rule 13a-14(a) Certification of Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2	Rule 13a-14(a) Certification of Principal Accounting and Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32.1	Certification pursuant to 18 U.S.C. Section 1350 by the Principal Executive Officer, as adopted, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2	Certification pursuant to 18 U.S.C. Section 1350 by the Principal Accounting and Financial Officer, as adopted, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS*	XBRL Instance Document
101.SCH*	XBRL Taxonomy Extension Schema Document
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*	XBRL Taxonomy Definition Linkbase Document
101.LAB*	XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase Document

^#  Compensatory plan or arrangement.

* XBRL (Extensible Business Reporting Language) information is furnished and not filed or a part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, is deemed not filed for purposes of Section 18 of the Securities Exchange Act of 1934, and otherwise is not subject to liability under these sections.

27

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	AtriCure, Inc.
	(REGISTRANT)
Date: August 2, 2013	/s/ Michael H. Carrel
	Michael H. Carrel
	President and Chief Executive Officer (Principal Executive Officer)
Date: August 2, 2013	/s/ M. Andrew Wade
	M. Andrew Wade
	Vice President and Chief Financial Officer (Principal Accounting and Financial Officer)

28

EXHIBIT INDEX

Exhibit No.	Description
10.1#	Amendment No. 1 to Employment Agreement, dated as of May 24, 2013, between AtriCure, Inc. and Michael H. Carrel
31.1	Rule 13a-14(a) Certification of Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2	Rule 13a-14(a) Certification of Principal Accounting and Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32.1	Certification pursuant to 18 U.S.C. Section 1350 by the Principal Executive Officer, as adopted, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2	Certification pursuant to 18 U.S.C. Section 1350 by the Principal Accounting and Financial Officer, as adopted, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS*	XBRL Instance Document
101.SCH*	XBRL Taxonomy Extension Schema Document
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*	XBRL Taxonomy Definition Linkbase Document
101.LAB*	XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase Document

^#  Compensatory plan or arrangement.

* XBRL (Extensible Business Reporting Language) information is furnished and not filed or a part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, is deemed not filed for purposes of Section 18 of the Securities Exchange Act of 1934, and otherwise is not subject to liability under these sections.

29

EX-10.1

Exhibit 10.1

AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT

THIS AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT (“Amendment No. 1”) is effective as of the      day of May 2013 (the “Effective Date”) between ATRICURE, INC., a Delaware corporation (the “Corporation”) and MICHAEL H. CARREL (the “Executive”).

RECITALS

A. The Corporation and the Executive have entered into that certain Employment Agreement, effective as of November 1, 2012 (the “Employment Agreement”), pursuant to which the Corporation retained the Executive.

B. The Corporation and the Executive now desire to amend the Employment Agreement as provided in this Amendment No. 1.

NOW, THEREFORE, in consideration of the mutual covenants and obligations hereinafter set forth, the parties hereto agree as follows:

1. Capitalized terms used but not defined in this Amendment No. 1 have the meanings assigned such terms in the Employment Agreement.

2. Section 3 of the Employment Agreement is hereby amended and restated to read in its entirety as follows:

“3. Work Location. The Executive shall perform his duties hereunder in such locations as may be required by the nature of such duties from time to time.”

3. Other than as set forth in this Amendment No. 1, all of the terms and conditions of the Employment Agreement shall continue in full force and effect.

4. This Amendment shall be governed by and construed in accordance with the laws of the State of Ohio, without reference to the conflicts of laws of the State of Ohio or any other jurisdiction.

[signature page follows]

IN WITNESS WHEREOF, the parties have duly executed this Amendment No. 1 to Employment Agreement effective as of the date first above written.

ATRICURE, INC.
By:
	M. Andrew Wade
	Vice President, Chief Financial Officer
EMPLOYEE
Michael H. Carrel

-2-

EX-31.1

Exhibit 31.1

CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER

PURSUANT TO

SECTION 13(a) OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Michael H. Carrel, certify that:

1. I have reviewed this quarterly report on Form 10-Q of AtriCure, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a. designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b. designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c. evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d. disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a. all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b. any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: August 2, 2013

By:	/s/ Michael H. Carrel
	Michael H. Carrel
	President and Chief Executive Officer
	(Principal Executive Officer)

EX-31.2

Exhibit 31.2

CERTIFICATION OF PRINCIPAL ACCOUNTING AND FINANCIAL OFFICER

PURSUANT TO

SECTION 13(a) OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, M. Andrew Wade, certify that:

1. I have reviewed this quarterly report on Form 10-Q of AtriCure, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a. designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b. designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c. evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d. disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a. all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b. any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: August 2, 2013

By:	/s/ M. Andrew Wade
	M. Andrew Wade
	Vice President and Chief Financial Officer
	(Principal Accounting and Financial Officer)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the quarterly report of AtriCure, Inc. (the “Company”) on Form 10-Q for the quarter ended June 30, 2013 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael H. Carrel, President and Chief Executive Officer and Principal Executive Officer of the Company, certify, pursuant to Rule 13a–14(b) and Section 1350 of Chapter 63 of Title 18 of the United States Code, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: August 2, 2013

By:	/s/ Michael H. Carrel
	Michael H. Carrel
	President and Chief Executive Officer
	(Principal Executive Officer)

A signed original of this written statement or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement has been provided to AtriCure, Inc. and will be retained by AtriCure, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

The foregoing certification is being furnished solely pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (Subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code) and is not being filed as part of the report or as a separate disclosure document.

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the quarterly report of AtriCure, Inc. (the “Company”) on Form 10-Q for the quarter ended June 30, 2013 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, M. Andrew Wade, Vice President and Chief Financial Officer and Principal Accounting and Financial Officer of the Company, certify, pursuant to Rule 13a–14(b) and Section 1350 of Chapter 63 of Title 18 of the United States Code, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: August 2, 2013

By:	/s/ M. Andrew Wade
	M. Andrew Wade
	Vice President and Chief Financial Officer
	(Principal Accounting and Financial Officer)

A signed original of this written statement or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement has been provided to AtriCure, Inc. and will be retained by AtriCure, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

The foregoing certification is being furnished solely pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (Subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code) and is not being filed as part of the report or as a separate disclosure document.

XML

Public Offering of Common Stock

6 Months Ended

Jun. 30, 2013

Equity [Abstract]

Public Offering of Common Stock

11. PUBLIC OFFERING OF COMMON STOCK

In January 2013 the Company completed a public offering of common stock under its July 2011 shelf registration. The Company sold 3,996 shares of common stock, par value $0.001 per share, at a price of $7.25 per share, generating proceeds of $26,872 after expenses. Offering costs were recorded in additional paid in capital to offset proceeds. The Company intends to use the proceeds from the offering for general corporate purposes and working capital.

XML

Condensed Consolidated Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Revenue	$ 20,429	$ 18,268	$ 39,859	$ 35,744
Cost of revenue	5,306	5,557	10,650	10,281
Gross profit	15,123	12,711	29,209	25,463
Operating expenses:
Research and development expenses	3,049	2,885	6,555	6,275
Selling, general and administrative expenses	13,713	11,146	26,093	22,005
Total operating expenses	16,762	14,031	32,648	28,280
Loss from operations	(1,639)	(1,320)	(3,439)	(2,817)
Other income (expense):
Interest expense	(132)	(201)	(305)	(426)
Interest income	2	2	6	4
Other	(17)	199	14	301
Loss before income tax expense	(1,786)	(1,320)	(3,724)	(2,938)
Income tax expense	5	6	10	8
Net loss	(1,791)	(1,326)	(3,734)	(2,946)
Basic and diluted net loss per share	$ (0.09)	$ (0.08)	$ (0.19)	$ (0.18)
Weighted average shares outstanding - basic and diluted	20,652	16,132	20,101	16,074
Comprehensive loss:
Unrealized losses on investments	(1)	(1)	(1)	(2)
Foreign currency translation adjustment	12	(106)	(132)	(51)
Other comprehensive income (loss)	11	(107)	(133)	(53)
Net loss	(1,791)	(1,326)	(3,734)	(2,946)
Comprehensive loss	$ (1,780)	$ (1,433)	$ (3,867)	$ (2,999)

XML

Intangible Assets

6 Months Ended

Jun. 30, 2013

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

4. INTANGIBLE ASSETS

Intangible assets with definite lives are amortized over their estimated useful lives. The following table provides a summary of the Company’s intangible assets with definite lives:

	Non-Compete Agreement
Net carrying amount as of December 31, 2011	$	45
Amortization		(13	)
Net carrying amount as of December 31, 2012		32
Amortization		(6	)
Net carrying amount as of June 30, 2013	$	26

The Company’s amortization term for a non-compete agreement is eight years. Amortization expense related to intangible assets with definite lives was $3 for both the three month periods ended June 30, 2013 and 2012 and $6 for both the six month periods ended June 30, 2013 and 2012.

Estimated future amortization expense related to intangible assets with definite lives is as follows:

Year	Amortization
2013	$	7
2014		12
2015		7
Total	$	26

XML

Equity Compensation Plans (Tables)

6 Months Ended

Jun. 30, 2013

Activity Under Stock Based Compensation Plans

Activity under the Plans during the six months ended June 30, 2013 was as follows:

Stock Options	Number of Shares Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at January 1, 2013		3,172		$	8.81
Granted		293			8.73
Exercised		(230	)		5.41
Cancelled or forfeited		(904	)		10.34
Outstanding at June 30, 2013		2,331		$	8.54		6.8	$	3,841
Vested and expected to vest		2,186		$	8.62		6.6	$	3,520
Exercisable at June 30, 2013		1,228		$	9.42		4.5	$	1,508

Restricted Stock	Number of Shares Outstanding			Weighted Average Grant Date Fair Value
Outstanding at January 1, 2013		504		$	7.93
Granted		20			8.92
Released		(84	)		9.44
Forfeited		(183	)		8.21
Outstanding at June 30, 2013		257		$	7.31

Summary of Share-Based Compensation Expense Related to Employee Share-Based Compensation

The following table summarizes share-based compensation expense related to employee share-based compensation under FASB ASC 718 for the three and six months ended June 30, 2013 and 2012. This expense was allocated as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Cost of revenue	$	69	$	68	$	127	$	134
Research and development expenses		59		92		100		132
Selling, general and administrative expenses		692		981		1,111		1,563
Total share-based compensation expense related to employees	$	820	$	1,141	$	1,338	$	1,829

Assumptions Used for Determining Fair Value of Options

In calculating compensation expense, the fair value of the options is estimated on the grant date using the Black-Scholes model including the following assumptions:

	Three Months Ended June 30,		Six Months Ended June 30,
	2013	2012	2013	2012
Risk free interest rate	0.75%–1.38%	1.16%–1.21%	0.75%–1.51%	0.85%–1.37%
Expected life of option (years)	5.33–6.91	6.85–7.06	5.31–7.38	5.39–7.14
Expected volatility of stock	69.00%	71.00%	69.00%	71.00%
Weighted-average volatility	69.00%	71.00%	69.00%	71.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Weighted Average Estimated Fair Value Per Share of the Stock Options and Restricted Stock Granted

Based on the assumptions noted above, the weighted average estimated fair value per share of the stock options and restricted stock granted for the respective periods was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Stock options	$	5.52	$	5.34	$	5.50	$	6.20
Restricted stock		8.92		8.21		8.92		9.86

Estimated Grant Date Fair Value Per Share of the Performance Options Granted

Based on the assumptions noted above, the estimated grant date fair value per share of the performance options granted in 2012 was as follows:

	Price Target		Fair Value
Tranche 1	$	10.00	$	4.32
Tranche 2		12.50		4.30
Tranche 3		15.00		4.27
Tranche 4		17.50		4.23
Tranche 5		20.00		4.19
Tranche 6		25.00		4.10
Tranche 7		30.00		4.01
Tranche 8		35.00		3.92
Tranche 9		40.00		3.83

Performance Shares [Member]

Assumptions Used for Determining Fair Value of Options

In calculating compensation expense for performance options, the fair value of the options was estimated on the grant date using a Monte Carlo simulation including the following assumptions:

Strike price	$	5.91
Contractual term		10.00
Expected volatility of stock		69.60	%
Expected rate of return		1.75	%
Dividend yield		0.00	%

XML

Description of Business and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Nature of the Business

Nature of the Business—AtriCure, Inc. (the “Company” or “AtriCure”) was incorporated in the State of Delaware on October 31, 2000. The Company provides innovative Atrial Fibrillation (“Afib”) solutions designed to produce superior outcomes that reduce the economic and social burden of Afib. The Company sells its products to hospitals globally through a direct sales force and distributors.

Basis of Presentation

Basis of Presentation—The accompanying interim financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”). The accompanying interim financial statements are unaudited, but in the opinion of the Company’s management, contain all of the normal, recurring adjustments considered necessary to present fairly the financial position, results of operations and cash flows for the periods presented in conformity with generally accepted accounting principles generally accepted in the United States (“GAAP”) applicable to interim periods. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted or condensed. The Company believes the disclosures herein are adequate to make the information presented not misleading. Results of operations are not necessarily indicative of the results expected for the full fiscal year or for any future period.

The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012 filed with the SEC.

Principles of Consolidation

Principles of Consolidation—The Condensed Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, the Company’s wholly-owned subsidiary organized in the State of Delaware, and AtriCure Europe B.V. (“AtriCure Europe”), the Company’s wholly-owned subsidiary incorporated in the Netherlands. All intercompany accounts and transactions have been eliminated in consolidation.

Cash and Cash Equivalents

Cash and Cash Equivalents—The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents.

Investments

Investments—The Company places its investments primarily in U.S. Government agencies and securities, corporate bonds and commercial paper. The Company classifies all investments as available-for-sale. Investments with maturities of less than one year are classified as short-term investments. Investments are recorded at fair value, with unrealized gains and losses recorded as accumulated other comprehensive income (loss). The Company recognizes gains and losses when these securities are sold using the specific identification method and includes them in interest income or expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss.

Revenue Recognition

Revenue Recognition—The Company accounts for revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, “Revenue Recognition” (“ASC 605”). The Company determines the timing of revenue recognition based upon factors such as passage of title, payment terms and ability to return products. The Company recognizes revenue when all of the following criteria are met: (i) there is persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured.

Revenue is generated from the sale of the Company’s surgical devices. The Company’s surgical devices consist primarily of individual disposable handpieces and equipment generators. The Company’s customers need the combination of the generator and the handpieces to have a functional system. The Company believes that the generator and handpiece are considered a single unit of accounting under ASC 605 because neither the generator nor handpiece have value to the customer on a standalone basis. Therefore, because the customer needs both the generator and handpiece to have a functional system, revenue is recognized upon the later of delivery of the generator or the handpiece.

Pursuant to the Company’s standard terms of sale, revenue is recognized when title to the goods and risk of loss transfers to customers and there are no remaining obligations that will affect the customers’ final acceptance of the sale. Generally, the Company’s standard terms of sale define the transfer of title and risk of loss to occur upon shipment to the respective customer. The Company generally does not maintain any post-shipping obligations to the recipients of the products. No installation, calibration or testing of this equipment is performed by the Company subsequent to shipment to the customer in order to render it operational.

Revenue includes shipping and handling revenue of $197 and $187 for the three months ended June 30, 2013 and 2012, respectively, and $389 and $377 for the six months ended June 30, 2013 and 2012, respectively. Cost of freight for shipments made to customers is included in cost of revenue. Sales and other value-added taxes collected from customers and remitted to governmental

authorities are excluded from revenue. The Company sells its products primarily through a direct sales force, with certain international markets sold through distributors. Terms of sale are generally consistent for both end-users and distributors except that payment terms are generally net 30 days for end-users and net 60 days for distributors.

Sales Returns and Allowances

Sales Returns and Allowances—The Company maintains a provision for sales returns and allowances to account for potential returns of defective or damaged products, products shipped in error and price adjustments. The Company estimates such provision quarterly based primarily on a specific identification basis, in addition to estimating a general reserve. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Condensed Consolidated Balance Sheets.

Allowance for Doubtful Accounts Receivable

Allowance for Doubtful Accounts Receivable—The Company evaluates the collectability of accounts receivable in order to determine the appropriate reserve for doubtful accounts. In determining the amount of the reserve, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs against the allowance has not been significant.

Inventories

Inventories—Inventories are stated at the lower of cost or market using the first-in, first-out cost method (“FIFO”) and consist of raw materials, work in process and finished goods. The Company’s industry is characterized by rapid product development and frequent new product introductions. Uncertain timing of product approvals, variability in product launch strategies and variation in product utilization all impact excess and obsolete inventory. An inventory reserve based on product usage is estimated and recorded quarterly for excess, slow moving and obsolete inventory, as well as inventory with a carrying value in excess of its net realizable value. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant.

Inventories consist of the following:

	June 30, 2013		December 31, 2012
Raw materials	$	2,269	$	3,066
Work in process		760		675
Finished goods		2,999		1,977
Inventories	$	6,028	$	5,718

Property and Equipment

Property and Equipment—Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method of depreciation for financial reporting purposes and applied over the estimated useful lives of the assets. The estimated useful life by major asset category is the following: machinery and equipment is three to seven years, computer and other office equipment is three years, furniture and fixtures is three to seven years and leasehold improvements and equipment leased under a capital lease are the shorter of their useful life or remaining lease term. The Company reassesses the useful lives of property and equipment annually, and assets are retired if they are no longer being used. Maintenance and repair costs are expensed as incurred.

Included in property and equipment are generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) that are loaned at no cost to direct customers that use the Company’s disposable products. These generators are depreciated over a period of one to three years, which approximates their useful lives, and such depreciation is included in cost of revenue. The estimated useful lives of this equipment are based on anticipated usage by our customers and the timing and impact of expected new technology rollouts by the Company. To the extent the Company experiences changes in the usage of this equipment or introductions of new technologies, the estimated useful lives of this equipment may change in a future period. Depreciation related to these generators was $299 and $357 for the three months ended June 30, 2013 and 2012, respectively, and $569 and $673 for the six months ended June 30, 2013 and 2012, respectively. As of June 30, 2013 and December 31, 2012, the net carrying amount of loaned equipment included in net property and equipment in the Condensed Consolidated Balance Sheets was $2,441 and $2,197, respectively.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets—The Company reviews property and equipment annually for impairment using its best estimates based on reasonable and supportable assumptions and projections.

Intangible Assets

Intangible Assets—Intangible assets with determinable useful lives are amortized on a straight-line basis over the estimated periods benefited, which range from four to eight years.

Other Income

Other Income—Other income consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants which are accounted for as free-standing derivatives. The Company recorded foreign currency transaction gains (losses) of $11 and ($39) for the three months ended June 30, 2013 and 2012, respectively, and $56 and ($35) for the six months ended June 30, 2013 and 2012, respectively, in connection with settlements of its intercompany balance with AtriCure Europe.

The Company periodically is awarded grants to support research and development activities. The Company recognizes grant income when the funds are earned. The Company recorded grant income of $0 and $201 during the three months ended June 30, 2013 and 2012, respectively. Grant income of $0 and $262 was recorded for the six month periods ended June 30, 2013 and 2012, respectively.

The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Because the non-employee options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these options, when vested, are no longer eligible for equity classification and are, thus, subsequently accounted for as derivative liabilities under FASB ASC 815, “Derivatives and Hedging” (“ASC 815”) until the awards are ultimately either exercised or forfeited. Accordingly, the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the three months ended June 30, 2013 and 2012, $28 and ($37), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options. During the six months ended June 30, 2013 and 2012, $42 and ($74), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options.

Taxes

Taxes—Income taxes are computed using the asset and liability method in accordance with FASB ASC 740, “Income Taxes” (“ASC 740”), under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more likely than not that such assets will not be fully realized. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates.

The Company’s estimate of the valuation allowance for deferred tax assets requires it to make significant estimates and judgments about its future operating results. The Company’s ability to realize the deferred tax assets depends on its future taxable income as well as limitations on their utilization. A deferred tax asset is reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized prior to its expiration. The projections of the Company’s operating results on which the establishment of a valuation allowance is based involve significant estimates regarding future demand for the Company’s products, competitive conditions, product development efforts, approvals of regulatory agencies and product cost. If actual results differ from these projections, or if the Company’s expectations of future results change, it may be necessary to adjust the valuation allowance. In evaluating whether to record a valuation allowance, the applicable accounting standards deem that the existence of cumulative losses in recent years is a significant piece of objectively verifiable negative evidence that must be overcome by objectively verifiable positive evidence to avoid the need to record a valuation allowance. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods.

A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended, (the “Patient Act”) requires manufacturers of medical devices to pay a 2.3% excise tax on all U.S. medical device sales beginning in January 2013. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $128 for the three months ended June 30, 2013 and $248 for the six months ended June 30, 2013.

Net Loss Per Share

Net Loss Per Share—Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (“ASC 260”) by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, net loss per share excludes the effect of 2,588 and 2,986 options, restricted stock and performance-based shares as of June 30, 2013 and 2012, respectively, because they are anti-dilutive. Therefore the number of shares calculated for basic net loss per share is also used for the diluted net loss per share calculation.

Comprehensive Loss and Accumulated Other Comprehensive Income (Loss)

Comprehensive Loss and Accumulated Other Comprehensive Income (Loss)—In addition to net losses, the comprehensive loss includes foreign currency exchange rate adjustments and unrealized gains and losses on investments.

Accumulated other comprehensive income (loss) consisted of the following:

	Unrealized Gains on Short- Term Investments			Foreign Currency Translation Adjustment			Accumulated Other Comprehensive Income (Loss)
Balance as of December 31, 2012	$	1		$	76		$	77
Other comprehensive income before reclassifications		0			(189	)		(189	)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			45			45
Net current-period other comprehensive income		0			(144	)		(144	)
Balance as of March 31, 2013	$	1		$	(68	)	$	(67	)
Other comprehensive income before reclassifications		(1	)		1			0
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			11			11
Net current-period other comprehensive income		(1	)		12			11
Balance as of June 30, 2013	$	0		$	(56	)	$	(56	)

Research and Development

Research and Development—Research and development costs are expensed as incurred. These costs include compensation and other internal and external costs associated with the development and research related to new products or concepts, preclinical studies, clinical trials and the cost of products used in trials and tests.

Share-Based Compensation

Share-Based Compensation—The Company follows FASB ASC 718, “Compensation-Stock Compensation” (“ASC 718”) to record share-based compensation for all employee share-based payment awards, including stock options, restricted stock, performance shares and stock purchases related to an employee stock purchase plan, based on estimated fair values. The Company’s share-based compensation expense recognized under ASC 718 for the three months ended June 30, 2013 and 2012 was $820 and $1,141, respectively, and $1,338 and $1,829 for the six months ended June 30, 2013 and 2012, respectively, on a before and after tax basis.

FASB ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Condensed Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. FASB ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

The Company estimates the fair value of time-based options on the date of grant using the Black-Scholes option-pricing model (“Black-Scholes model”). The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price, as well as assumptions regarding a number of highly complex and subjective variables. These variables include but are not limited to the Company’s expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. For non-employee options, the fair value at the date of grant is subject to adjustment at each vesting date based upon the fair value of the Company’s common stock. The fair value of market-based performance option grants is estimated at the date of grant using a Monte-Carlo simulation. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in our Condensed Consolidated Statements of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures.

The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company’s determination of fair value is affected by the Company’s stock price as well as assumptions regarding the number of shares expected to be granted.

The Company also has an employee stock purchase plan (“ESPP” or the “Plan”) which is available to all eligible employees as defined by the Plan. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the Plan and records compensation expense based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model.

The Company has historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. The Company accounts for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50, “Equity-Based Payments to Non-Employees” (“ASC 505-50”). Because these options do not contain specific performance provisions, there is no measurement date of fair value until the options vest. Therefore, the fair value of the options granted and outstanding prior to their vesting date is remeasured each reporting period.

Fully vested options to acquire 38 shares of common stock held by non-employee consultants remained unexercised as of both June 30, 2013 and December 31, 2012. A liability of $120 and $78 was included in accrued liabilities in the Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012, respectively.

Use of Estimates

Use of Estimates—The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.

Fair Value Disclosures

Fair Value Disclosures—The book value of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, short-term investments, short and long-term other assets, accounts payable, accrued expenses, other liabilities and fixed interest rate debt, approximate their fair values. The Company classifies cash and short-term investments in U.S. government agencies and securities as Level 1 within the fair value hierarchy. Accounts receivable, short-term other assets, accounts payable and accrued expenses are also classified as Level 1. The carrying amounts of these assets and liabilities approximate their fair value due to their relatively short-term nature. Other assets and other liabilities are classified as Level 1 within the fair value hierarchy. Cash equivalents and short-term investments in commercial paper are classified as Level 2 within the fair value hierarchy (see Note 3 – “Fair Value” for further information). Fixed interest rate debt fair value is determined by calculating the net present value of future debt payments and is classified as Level 2. Significant unobservable inputs with respect to the fair value measurement of the Level 3 non-employee stock options are developed using Company data. When an input is changed, the Black-Scholes model is updated and the results are analyzed for reasonableness.

Segment Reporting

The Company considers reporting segments in accordance with FASB ASC 280, “Segment Reporting”. The Company develops, manufactures, and sells devices designed primarily for the surgical ablation of cardiac tissue and systems designed for the exclusion of the left atrial appendage. These devices are developed and marketed to a broad base of medical centers in the United States and internationally. Management considers all such sales to be part of a single reportable segment.

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Segment and Geographic Information - Revenue by Product (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Product Type Reporting Information [Line Items]
Revenue	$ 20,429	$ 18,268	$ 39,859	$ 35,744
Open-Heart [Member]
Product Type Reporting Information [Line Items]
Revenue	9,154	8,386	18,275	16,873
Minimally Invasive [Member]
Product Type Reporting Information [Line Items]
Revenue	3,511	3,264	6,643	6,212
Atriclip [Member]
Product Type Reporting Information [Line Items]
Revenue	2,789	1,761	5,175	3,520
United States [Member]
Product Type Reporting Information [Line Items]
Revenue	15,454	13,411	30,093	26,605
International [Member]
Product Type Reporting Information [Line Items]
Revenue	$ 4,975	$ 4,857	$ 9,766	$ 9,139

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Commitments and Contingencies - Additional Information (Detail) In Thousands, unless otherwise specified	1 Months Ended		3 Months Ended				6 Months Ended		12 Months Ended			13 Months Ended	6 Months Ended
	Apr. 30, 2012 Unit	Dec. 31, 2009 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2010 EUR (€)	Jun. 30, 2013 USD ($) Unit	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($) Unit	Dec. 31, 2010 USD ($)	Dec. 31, 2010 EUR (€)	Dec. 31, 2011 Unit	Jun. 30, 2013 Minimum [Member] USD ($)	Jun. 30, 2013 Maximum [Member] USD ($)
Commitments and Contingencies [Line Items]
Operating leases expire at various terms							2015
Royalty agreement term													3 years	20 years
Royalty rates													1.50%	5.00%
Royalty payments													$ 50	$ 2,000
Royalty expense			217	151			539	298
Minimum units the company was required to purchase												40
Purchases of additional units							40
Total quantity purchased												56
Actual quantity purchased							35		60
Number of radio frequency generators manufacture	300
Parties signed a Definitive Stipulation of Settlement agreement							October 1, 2010
Distributor earnings					65	50				520	400
Operating expenses related to investigation		3,956
Definitive stipulation of settlement agreement		4,350
Interest payment term							5 years
Settlement agreement payments (including interest)							2,575
Liability related settlement			1,736				1,736
Liability related settlement current			$ 1,364				$ 1,364		$ 1,120
Company integrity agreement with office of inspector general							5 years

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Description of Business and Summary of Significant Accounting Policies - Summary of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Raw materials	$ 2,269	$ 3,066
Work in process	760	675
Finished goods	2,999	1,977
Inventories	$ 6,028	$ 5,718

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Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Description Of Business And Significant Accounting Policies [Line Items]
Maturity period of highly liquid investments			3 months
Maturity period of short term investment			1 year
Shipping and handling revenue	$ 197	$ 187	$ 389	$ 377
Payment terms for end-users			30 days
Payment terms for distributors			60 days
Cost of lending disposable products to direct customers			0
Foreign currency transaction (losses) gains	12	(106)	(132)	(51)
Grant income	0	201	0	262
Income (expense) related to remeasurement of fair value of fully vested stock options	28	(37)	42	(74)
Percentage of excise tax to be paid by manufacturers of medical devices			2.30%
Company's expense related to the medical device excise tax	128		248
Options, restricted stock and performance based shares excluded from calculation of net loss per share			2,588	2,986
Recognized expense related to stock options and restricted stock	820	1,141	1,338	1,829
Unexercised shares of common stock held by non-employee consultants	38		38		38
Accrued non-employee stock options	120		120		78
Minimum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful lives of intangible assets			4 years
Maximum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful lives of intangible assets			8 years
Subsidiaries [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Foreign currency transaction (losses) gains	11	(39)	56	(35)
Machinery and Equipment [Member] | Minimum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			3 years
Machinery and Equipment [Member] | Maximum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			7 years
Computer and Other Office Equipment [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			3 years
Furniture and Fixtures [Member] | Minimum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			3 years
Furniture and Fixtures [Member] | Maximum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			7 years
Generators [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Depreciation	299	357	569	673
Generators [Member] | Minimum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			1 year
Generators [Member] | Maximum [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Estimated useful life by major asset category			3 years
Carrying Amount of Loaned Equipment [Member]
Description Of Business And Significant Accounting Policies [Line Items]
Net carrying amount of loaned equipment	$ 2,441		$ 2,441		$ 2,197

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Equity Compensation Plans - Estimated Grant Date Fair Value Per Share of Performance Options Granted (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012 Tranche 1 [Member]	Dec. 31, 2012 Tranche 2 [Member]	Dec. 31, 2012 Tranche 3 [Member]	Dec. 31, 2012 Tranche 4 [Member]	Dec. 31, 2012 Tranche 5 [Member]	Dec. 31, 2012 Tranche 6 [Member]	Dec. 31, 2012 Tranche 7 [Member]	Dec. 31, 2012 Tranche 8 [Member]	Dec. 31, 2012 Tranche 9 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Price Target					$ 10.00	$ 12.50	$ 15.00	$ 17.50	$ 20.00	$ 25.00	$ 30.00	$ 35.00	$ 40.00
Fair Value	$ 5.52	$ 5.34	$ 5.50	$ 6.20	$ 4.32	$ 4.30	$ 4.27	$ 4.23	$ 4.19	$ 4.10	$ 4.01	$ 3.92	$ 3.83

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Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets with Definite Lives (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
2013	$ 7
2014	12
2015	7
Total	$ 26

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Equity Compensation Plans - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended		1 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended					6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Maximum [Member]	Jun. 30, 2013 Minimum [Member]	Nov. 30, 2012 Performance Shares [Member]	Jun. 30, 2013 Performance Shares [Member]	Jun. 30, 2012 Performance Shares [Member]	Jun. 30, 2013 Performance Shares [Member]	Jun. 30, 2012 Performance Shares [Member]	Jun. 30, 2013 ESPP [Member]	Jun. 30, 2012 ESPP [Member]	Jun. 30, 2013 ESPP [Member]	Jun. 30, 2012 ESPP [Member]	Jun. 30, 2013 ESPP [Member] Maximum [Member]	Jun. 30, 2013 Stock Options And Restricted Stock [Member]	Jun. 30, 2012 Stock Options And Restricted Stock [Member]	Jun. 30, 2013 Stock Options And Restricted Stock [Member]	Jun. 30, 2012 Stock Options And Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2013 Employee Stock Option [Member]	Jun. 30, 2013 2005 Plan [Member]	Dec. 31, 2012 2005 Plan [Member]	Jun. 30, 2013 2005 Plan [Member] Restricted Stock [Member]	Jun. 30, 2013 2005 Plan [Member] Employee Stock Option [Member]	Jun. 30, 2013 2001 Plan [Member]	Jun. 30, 2013 2001 Plan [Member] Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiry of options from the date of grant											10 years																10 years				10 years
Exercisable period beginning																										1 year
Options granted exercisable cumulative																														25.00%		25.00%
Options granted from the 2005 Plan generally vest																											3 years		4 years
Common stock reserved for issuance																											6,893,000	549,000
Percentage of outstanding shares of common stock on the first day																											3.25%
Outstanding shares of common stock on the first day																											825,000
Outstanding shares authorized on that date																												3.25%
Shares available for future grants																											1,755,000
Total intrinsic value of options exercised	$ 135	$ 1,093	$ 599	$ 1,244
Cash proceeds			1,240	434
Total fair value of performance shares vested									0	0	0	99
Total fair value of restricted stock vested																						98	114	705	724
Tax benefit recognized	0	0	0	0
Recognized expense related to stock options and restricted stock	820	1,141	1,338	1,829					0	0	0	0	73	54	132	152		747	1,087	1,206	1,677
Unrecognized compensation costs related to non-vested share-based compensation arrangements with performance shares	8,942		8,942						0		0
Stock options compensation costs																										6,032
Unrecognized compensation costs related to non-vested performance options									549		549											2,910		2,910
Weighted average period of recognizing cost						5 years 2 months 19 days	2 years 5 months 12 days																	2 years 10 months 24 days		3 years 2 months 12 days
Incremental compensation expenses		396
Performance options awarded to President and CEO			293,000					225,000
Number of shares options vest in											25,000
Period of considering closing price of common stock											30 days
Price by which volume adjusted weighted average closing price exceeds under vesting condition 1											$ 10.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 2											$ 12.50
Price by which volume adjusted weighted average closing price exceeds under vesting condition 3											$ 15.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 4											$ 17.50
Price by which volume adjusted weighted average closing price exceeds under vesting condition 5											$ 20.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 6											$ 25.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 7											$ 30.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 8											$ 35.00
Price by which volume adjusted weighted average closing price exceeds under vesting condition 9											$ 40.00
Recognized expense related to performance options			1,338	1,829					45		83
Performance shares (gross) released											0	10,000
Performance Shares outstanding									0		0
Company's common stock may be purchased at a discount															15.00%
Participants purchase limit value																	25
Description of participants purchase limit			Participants may not purchase more than $25 of the Company's common stock in a calendar year and, effective January 1, 2009, may not purchase more than 1.5 shares during an offering period
Participants purchase limit shares	1.5		1.5
Offering period			6 months
Shares available for sale under the ESPP increased															2.00%
Outstanding shares of common stock exceed															600,000
Shares available for future issuance under the ESPP													720,000		720,000
Nonstatutory common stock options vest period maximum			4 years
Stock options granted to non-employee consultants vesting period			4 years
Non-employee Vesting stock rate			25.00%
Non-employee consultant stock options granted			0
Expense (income)	28	(37)	42	(74)
Unexercised shares of common stock held by non-employee consultants	38,000		38,000		38,000
Liability included in accrued liabilities	$ 120		$ 120		$ 78

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Public Offering of Common Stock - Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	6 Months Ended
	Jan. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Equity [Abstract]
Common stock sold	3,996
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock , price per share	$ 7.25
Proceeds from issuance of common stock	$ 26,872	$ 26,872

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Fair Value - Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Beginning Balance	$ 78	$ 208
Total gains/losses (realized/unrealized) included in earnings	42	(179)
Purchases (exercises)		(50)
Reclassification from equity to liability when fully vested		99
Ending Balance	120	78
Gains/Losses included in earnings (or changes in net assets attributable to the change in unrealized gains/losses relating to assets held at reporting date)	$ (42)	$ 179

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Equity Compensation Plans - Assumptions Used for Determining Fair Value of Options (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility of stock	69.00%	71.00%	69.00%	71.00%
Weighted-average volatility	69.00%	71.00%	69.00%	71.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.75%	1.16%	0.75%	0.85%
Expected life of option (years)	5 years 3 months 29 days	6 years 10 months 6 days	5 years 3 months 22 days	5 years 4 months 21 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.38%	1.21%	1.51%	1.37%
Expected life of option (years)	6 years 10 months 28 days	7 years 22 days	7 years 4 months 17 days	7 years 1 month 21 days

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Segment and Geographic Information (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Summary of Geographic Revenue

Geographic revenue was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
United States	$	15,454	$	13,411	$	30,093	$	26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

Revenue by Product

Revenue by product type was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
Revenue:	2013		2012		2013		2012
Open-heart	$	9,154	$	8,386	$	18,275	$	16,873
Minimally Invasive		3,511		3,264		6,643		6,212
AtriClip		2,789		1,761		5,175		3,520
Total United States		15,454		13,411		30,093		26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

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Condensed Consolidated Statements of Cash Flows (Parenthetical) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Statement Of Cash Flows [Abstract]
Offering cost for sale of stock	$ 212

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Recent Accounting Pronouncements

6 Months Ended

Jun. 30, 2013

Accounting Changes And Error Corrections [Abstract]

Recent Accounting Pronouncements

2. RECENT ACCOUNTING PRONOUNCEMENTS

In February 2013 the FASB issued FASB Accounting Standards Update (“ASU”) 2013-02, “Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income”. This new guidance requires presentation of the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source and the income statement line items affected by the reclassification. If a component is not required to be reclassified to net income in its entirety, a cross reference to the related footnote for additional information will be required. This ASU is effective for interim and annual reporting periods beginning after December 15, 2012. The Company has evaluated the provisions of ASU 2013-02 and determined that the new guidance does not have a material impact on the Company’s financial reporting.

In July 2013 the FASB issued FASB ASU 2013-11, “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists”. This new guidance eliminates the diversity in practice for the financial statement presentation of unrecognized tax benefits when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. This ASU is effective for interim and annual reporting periods beginning after December 15, 2013. The Company has evaluated the provisions of ASU 2013-11 and determined that the guidance does not have a material impact on the Company’s financial reporting.

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Accrued Liabilities

6 Months Ended

Jun. 30, 2013

Payables And Accruals [Abstract]

Accrued Liabilities

5. ACCRUED LIABILITIES

Accrued liabilities consisted of the following:

	June 30, 2013		December 31, 2012
Accrued commissions	$	1,932	$	1,464
Accrued settlement reserve (current portion)		1,364		1,120
Accrued bonus		911		487
Other accrued liabilities		477		707
Accrued vacation		391		349
Accrued taxes and value-added taxes payable		360		366
Accrued payroll		178		153
Accrued royalty		172		118
Withheld payroll taxes		166		126
Accrued non-employee stock options		120		78
Sales/returns allowance—trade		105		105
Total	$	6,176	$	5,073

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Fair Value

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Fair Value

3. FAIR VALUE

FASB ASC 820, “Fair Value Measurements and Disclosures” (“ASC 820”) defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following:

• Level 1—Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. An active market for the asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. The valuation under this approach does not entail a significant degree of judgment.

• Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The valuation technique for the Company’s Level 2 assets is based on quoted market prices for similar assets from observable pricing sources at the reporting date.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Unobservable inputs shall be used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The fair value of the Company’s Level 3 investments are estimated on the grant date using the Black-Scholes model and they are revalued at the end of each reporting period using the Black-Scholes model.

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of June 30, 2013:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	29,464	$	—	$	29,464
Commercial paper		—		2,898		—		2,898
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	32,362	$	—	$	33,362
Liabilities:
Derivative instruments	$	—	$	—	$	120	$	120
Total liabilities	$	—	$	—	$	120	$	120

There were no changes in the levels of financial assets and liabilities during the three or six month periods ended June 30, 2013.

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2012:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	5,261	$	—	$	5,261
Commercial paper		—		3,247		—		3,247
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	8,508	$	—	$	9,508
Liabilities:
Derivative instruments	$	—	$	—	$	78	$	78
Total liabilities	$	—	$	—	$	78	$	78

The fair value of the Level 3 liabilities is estimated using the Black-Scholes model including the following assumptions:

	As of June 30, 2013	As of December 31, 2012
Risk free interest rate	0.20% – 1.26%	0.23% – 0.74%
Expected life of option (years)	1.25 – 4.61	1.75 – 5.10
Expected volatility of stock	69.00%	70.00%
Dividend yield	0.00%	0.00%

The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Once these non-employee options have vested, the awards no longer fall within the scope of ASC 505-50. Because the options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these vested options are no longer eligible for equity classification and are, thus, accounted for as derivative liabilities under FASB ASC 815 until the awards are ultimately either exercised or forfeited. Accordingly,

the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. In calculating the fair value of the options, they are estimated on the grant date using the Black-Scholes model subject to change in stock price utilizing assumptions of risk-free interest rate, contractual life of option, expected volatility and dividend yield. Due to the lack of certain observable market quotes, the Company utilizes valuation models that rely on some Level 3 inputs. The Company’s estimate of volatility is based on the Company’s trading history. In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of June 30, 2013:

Beginning Balance–January 1, 2013	$	78
Total gains/losses (realized/unrealized) included in earnings		42
Purchases (exercises)		—
Reclassification from equity to liability when fully vested		—
Ending Balance–June 30, 2013	$	120
Losses included in earnings (or changes in net assets attributable to the change in unrealized gains relating to assets held at reporting date)	$	(42	)

In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of December 31, 2012:

Beginning Balance–January 1, 2012	$	208
Total gains/losses (realized/unrealized) included in earnings		(179	)
Purchases (exercises)		(50	)
Reclassification from equity to liability when fully vested		99
Ending Balance–December 31, 2012	$	78
Gains included in earnings (or changes in net assets attributable to the change in unrealized losses relating to assets held at reporting date)	$	179

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Equity Compensation Plans - Activity Under Stock Based Compensation Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of Shares Outstanding, Stock Options			3,172
Granted, Number of Shares Outstanding, Stock Options			293
Exercised, Number of Shares Outstanding, Stock Options			(230)
Cancelled or forfeited, Number of Shares Outstanding, Stock Options			(904)
Ending balance, Number of Shares Outstanding, Stock Options	2,331		2,331
Vested and expected to vest, Number of Shares Outstanding, Stock Options	2,186		2,186
Exercisable at June 30, Number of Shares Outstanding, Stock Options	1,228		1,228
Beginning balance, Weighted Average Exercise Price, Stock Options			$ 8.81
Granted, Weighted Average Exercise Price, Stock Options			$ 8.73
Exercised, Weighted Average Exercise Price, Stock Options			$ 5.41
Cancelled or Forfeited, Weighted Average Exercise Price, Stock Options			$ 10.34
Ending balance, Weighted Average Exercise Price, Stock Options	$ 8.54		$ 8.54
Vested And expected to vest, Weighted Average Exercise Price, Stock Options	$ 8.62		$ 8.62
Exercisable at June 30, Weighted Average Exercise Price, Stock Options	$ 9.42		$ 9.42
Outstanding at June 30, Weighted Average Remaining Contractual Term, Stock Options			6 years 9 months 18 days
Vested and expected to vest, Weighted Average Remaining Contractual Term, Stock Options			6 years 7 months 6 days
Exercisable at June 30, Weighted Average Remaining Contractual Term, Stock Options			4 years 6 months
Outstanding at June 30, Aggregate Intrinsic Value, Stock Options	$ 3,841		$ 3,841
Vested and expected to vest, Aggregate Intrinsic Value, Stock Options	3,520		3,520
Exercisable at June 30, Aggregate Intrinsic Value, Stock Options	$ 1,508		$ 1,508
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Number of Shares Outstanding			504
Granted, Number of Shares Outstanding			20
Released, Number of Shares Outstanding			(84)
Forfeited, Number of Shares Outstanding			(183)
Ending balance, Number of Shares Outstanding	257		257
Beginning balance, Weighted Average Grant Date Fair Value			$ 7.93
Granted, Weighted Average Grant Date Fair Value	$ 8.92	$ 8.21	$ 8.92	$ 9.86
Released, Weighted Average Grant Date Fair Value			$ 9.44
Forfeited, Weighted Average Grant Date Fair Value			$ 8.21
Ending balance, Weighted Average Grant Date Fair Value	$ 7.31		$ 7.31

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Description of Business and Summary of Significant Accounting Policies - Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of December 31, 2012	$ (67)	$ 77		$ 77
Other comprehensive income before reclassifications	0	(189)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations	11	45
Other comprehensive income (loss)	11	(144)	(107)	(133)	(53)
Balance as of June 30, 2013	(56)	(67)		(56)
Unrealized Gains On Short-Term Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of December 31, 2012	1	1		1
Other comprehensive income before reclassifications	(1)	0
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations	0	0
Other comprehensive income (loss)	(1)	0
Balance as of June 30, 2013	0	1		0
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of December 31, 2012	(68)	76		76
Other comprehensive income before reclassifications	1	(189)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations	11	45
Other comprehensive income (loss)	12	(144)
Balance as of June 30, 2013	$ (56)	$ (68)		$ (56)

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Intangible Assets - Summary of Company's Intangible Assets with Definite Lives (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Non-Compete Agreement [Member]	Dec. 31, 2012 Non-Compete Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Net carrying amount, Beginning balance					$ 32	$ 45
Amortization	(3)	(3)	(6)	(6)	(6)	(13)
Net carrying amount, Ending balance	$ 26		$ 26		$ 26	$ 32

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Indebtedness - Maturities on Long-Term Debt, Including Capital Lease Obligations (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Debt Disclosure [Abstract]
2013	$ 1,015
2014	2,032
2015	2,026
2016	2,016
2017	333
Total	$ 7,422

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Equity Compensation Plans - Assumptions Used for Determining Fair Value of Option (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility of stock	69.00%	71.00%	69.00%	71.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Strike price			$ 5.91
Contractual term			10 years
Expected volatility of stock			69.60%
Risk free/Expected interest rate			1.75%
Dividend yield			0.00%

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Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 39	$ 49
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	90,000	90,000
Common stock, shares issued	20,980	16,896
Common stock, shares outstanding	20,980	16,896

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Income Tax Provision

6 Months Ended

Jun. 30, 2013

Income Tax Disclosure [Abstract]

Income Tax Provision

8. INCOME TAX PROVISION

The Company files federal, state, and foreign income tax returns in jurisdictions with varying statutes of limitations. Income taxes are computed using the asset and liability method in accordance with FASB ASC 740 under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more likely than not that such assets will not be fully realized. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates. The Company does not expect any significant unrecognized tax benefits to arise over the next twelve months.

The Company’s provision for income taxes for continuing operations in interim periods is computed by applying its estimated annual effective rate against its loss before income tax (expense) benefit for the period. In addition, non-recurring or discrete items are recorded during the period in which they occur. The effective tax rate for the three months ended June 30, 2013 and 2012 was (0.28%) and (0.44%), respectively. The effective tax rate for the six months ended June 20, 2013 and 2012 was (0.27%) and (0.29%), respectively.

The Company has not accrued interest and penalties related to unrecognized income tax benefits. However, when or if the situation occurs, the Company will recognize interest and penalties within the income tax expense line in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss and within the related tax liability in the Condensed Consolidated Balance Sheets.

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Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net loss	$ (3,734)	$ (2,946)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	1,338	1,829
Depreciation	951	1,047
Loss (gain) on disposal of equipment	29	(9)
Amortization of deferred financing costs	46	69
Amortization of intangible assets	6	6
Amortization/accretion on investments	(6)	19
Change in allowance for doubtful accounts	2	19
Changes in assets and liabilities:
Accounts receivable	(1,463)	(916)
Inventories	(320)	39
Other current assets	(240)	(176)
Accounts payable	45	(384)
Accrued liabilities	375	292
Other non-current assets and non-current liabilities	139	(171)
Net cash used in operating activities	(2,832)	(1,282)
Cash flows from investing activities:
Purchases of property and equipment	(1,191)	(1,395)
Purchases of available-for-sale securities	(2,544)	(6,692)
Maturities of available-for-sale securities	2,900	4,800
Net proceeds from the sale of equipment		24
Net cash used in investing activities	(835)	(3,263)
Cash flows from financing activities:
Proceeds from sale of stock, net of offering costs of $212	26,872
Proceeds from debt borrowings		10,000
Payments on debt and capital leases	(1,014)	(7,063)
Payment of debt fees	(98)	(76)
Proceeds from issuance of common stock under employee stock purchase plan	326	372
Proceeds from stock option exercises	1,240	434
Shares repurchased for payment of taxes on stock awards	(269)	(228)
Net cash provided by financing activities	27,057	3,439
Effect of exchange rate changes on cash and cash equivalents	(99)	7
Net increase (decrease) in cash and cash equivalents	23,291	(1,099)
Cash and cash equivalents - beginning of period	7,753	9,759
Cash and cash equivalents - end of period	31,044	8,660
Supplemental cash flow information:
Cash paid for interest	279	297
Cash paid for taxes	30	12
Non-cash investing activities:
Accrued purchases of property and equipment	$ 63	$ 23

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Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 31,044	$ 7,753
Short-term investments	3,898	4,247
Accounts receivable, less allowance for doubtful accounts of $39 and $49, respectively	11,344	9,948
Inventories	6,028	5,718
Other current assets	1,152	873
Total current assets	53,466	28,539
Property and equipment, net	3,685	3,430
Intangible assets	26	32
Other assets	304	430
Total Assets	57,481	32,431
Current liabilities:
Accounts payable	5,196	5,103
Accrued liabilities	6,176	5,073
Current maturities of long-term debt and capital lease obligations	2,031	2,029
Total current liabilities	13,403	12,205
Long-term debt and capital lease obligations	5,391	6,407
Other liabilities	547	1,319
Total Liabilities	19,341	19,931
Commitments and contingencies (Note 7)
Stockholders' Equity:
Common stock, $.001 par value, 90,000 shares authorized and 20,980 and 16,896 issued and outstanding, respectively	21	17
Additional paid-in capital	152,660	123,157
Accumulated other comprehensive (loss) income	(56)	77
Accumulated deficit	(114,485)	(110,751)
Total Stockholders' Equity	38,140	12,500
Total Liabilities and Stockholders' Equity	$ 57,481	$ 32,431

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Fair Value - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets:
Total assets	$ 33,362	$ 9,508
Liabilities:
Derivative instruments	120	78
Total liabilities	120	78
Money Market Funds [Member]
Assets:
Total assets	29,464	5,261
Commercial Paper [Member]
Assets:
Total assets	2,898	3,247
U.S. Government Agencies and Securities [Member]
Assets:
Total assets	1,000	1,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	1,000	1,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Agencies and Securities [Member]
Assets:
Total assets	1,000	1,000
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	32,362	8,508
Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member]
Assets:
Total assets	29,464	5,261
Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper [Member]
Assets:
Total assets	2,898	3,247
Significant Other Unobservable Inputs (Level 3) [Member]
Liabilities:
Derivative instruments	120	78
Total liabilities	$ 120	$ 78

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Indebtedness (Tables)

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Maturities on Long-Term Debt, Including Capital Lease Obligations

Maturities on long-term debt, including capital lease obligations, are as follows:

2013	$	1,015	July 1, 2013 through December 31, 2013
2014		2,032
2015		2,026
2016		2,016
2017		333
Total	$	7,422

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Equity Compensation Plans - Weighted Average Estimated Fair Value Per Share of Stock Options and Restricted Stock Granted (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average estimated grant date fair value per share of the stock options granted	$ 5.52	$ 5.34	$ 5.50	$ 6.20
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average estimated grant date fair value per share of the restricted stock granted	$ 8.92	$ 8.21	$ 8.92	$ 9.86

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Income Tax Provision - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Tax Disclosure [Abstract]
Effective tax rate	(0.28%)	(0.44%)	(0.27%)	(0.29%)

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Accrued Liabilities - Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Payables And Accruals [Abstract]
Accrued commissions	$ 1,932	$ 1,464
Accrued settlement reserve (current portion)	1,364	1,120
Accrued bonus	911	487
Other accrued liabilities	477	707
Accrued vacation	391	349
Accrued taxes and value-added taxes payable	360	366
Accrued payroll	178	153
Accrued royalty	172	118
Withheld payroll taxes	166	126
Accrued non-employee stock options	120	78
Sales/returns allowance-trade	105	105
Total	$ 6,176	$ 5,073

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Indebtedness - Additional Information (Detail) In Thousands, unless otherwise specified	1 Months Ended	6 Months Ended				6 Months Ended			6 Months Ended	12 Months Ended	1 Months Ended
	Mar. 29, 2013	Jun. 30, 2013 USD ($)	Jun. 30, 2013 EUR (€)	Dec. 31, 2012 EUR (€)	Jun. 30, 2012	Jun. 30, 2013 Term Loan [Member] USD ($)	Mar. 29, 2013 Term Loan [Member]	Dec. 31, 2012 Term Loan [Member] USD ($)	Jun. 30, 2013 Revolving Credit Facility [Member] USD ($)	Dec. 31, 2012 Revolving Credit Facility [Member] USD ($)	Mar. 29, 2013 Revolving Credit Facility Modification Agreement [Member]	Mar. 29, 2013 Term Loan Modification Agreement [Member]
Credit Facilities [Line Items]
Term loan arrangements		$ 10,000
Revolving credit facility maturity date						Feb. 02, 2017			Apr. 30, 2014
Credit facility		10,000							7,957	5,303
Increase to the applicable interest rate		3.00%	3.00%
Interest on the revolving loan accrued at a fluctuating borrowing rate above the prime rate	0.25%										1.25%
Interest rate in addition to the prime rate during a Non-Streamline Period	1.25%
Reduction of fixed interest rate on the term loan							6.75%					4.75%
Interest rate on term loan		4.75%	4.75%		6.75%
Amount outstanding under line of credit						7,333		8,333
Current maturities of long-term debt						2,000
Borrowings under the revolving credit facility									0	0
Interest on the term loan portion accrued						6.50%
Letter of credit outstanding			75	0
Expiry of outstanding letter of credit		Jun. 30, 2015	Jun. 30, 2015
Capital lease expiration period		2016	2016
Cost of assets under lease		226
Accumulated amortization on the capital leases		$ 142

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2013

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. COMMITMENTS AND CONTINGENCIES

Operating Leases

The Company leases various types of office, manufacturing and warehouse facilities and equipment under noncancelable operating leases that expire at various terms through 2015.

Royalty Agreements

The Company has certain royalty agreements in place with terms that include payment of royalties based on product revenue from sales of current products. The royalty agreements have effective dates as early as 2003 and terms ranging from three years to at least twenty years. The royalties range from 1.5% to 5% of product sales. One of the agreements includes minimum quarterly payments of $50 through 2015 and a maximum of $2,000 in total royalties over the term of the agreement. Parties to the royalty agreements have the right at any time to terminate the agreement immediately for cause. Royalty expense of $217 and $151 was recorded as part of cost of revenue for the three months ended June 30, 2013 and 2012, respectively, and $539 and $298 for the six months ended June 30, 2013 and 2012, respectively.

Purchase Agreements

On June 15, 2007 the Company entered into a purchase agreement with MicroPace Pty Ltd Inc. (“MicroPace”). The agreement, as amended, provides for MicroPace to produce a derivative of one of their products tailored for the cardiac surgical environment, known as the “MicroPace ORLab^™” for worldwide distribution by the Company. Pursuant to the terms of the amended agreement, in order for the Company to retain exclusive distribution rights, the Company was required to purchase a minimum of 40 units during the period December 1, 2010 through December 31, 2011 to extend exclusivity through 2012 and an additional 40 units during 2012 to extend exclusivity through December 31, 2013. Units purchased in excess of yearly minimums reduce future minimum purchase requirements. A total of 56 units were purchased by the Company between December 1, 2010 and December 31, 2011, thereby extending exclusive distribution rights through December 31, 2012. A total of 60 units were purchased by the Company during 2012, fulfilling the purchase requirement to extend exclusive distribution rights through 2013. The Company purchased 35 units during the first half of 2013.

In April 2012 the Company entered into a development and manufacturing services agreement with Stellartech Research Corporation (“Stellartech”). Under the terms of the agreement, Stellartech will provide development services for the next generation of the Company’s radio frequency generators and will manufacture at least the first 300 units of the product. The agreement also establishes Stellartech as the exclusive supplier of the generators during the three years after product completion. There is no minimum purchase requirement beyond the initial 300 units.

Distributor Termination

In July 2010 the Company terminated a distributor agreement with a European distributor. Under the terms of the agreement the Company paid the distributor a termination fee, repurchased saleable disposable product inventory and assigned the distributor’s capital equipment to AtriCure Europe. Additionally, the Company entered into a consulting agreement with the distributor to provide ongoing consulting services through September 30, 2012. In exchange for these services, beginning October 1, 2010, the distributor earned €50 (approximately $65) per quarter for a total of €400 (approximately $520).

Legal

The Company is not party to any material pending or threatened litigation, except as described below:

Department of Justice Investigation

In October 2008 the Company received a letter from the Department of Justice (“DOJ”) informing the Company that it was conducting an investigation for potential False Claims Act (“FCA”) and common law violations relating to its surgical ablation devices. Specifically, the letter stated that the DOJ was investigating the Company’s marketing practices utilized in connection with its surgical ablation system to treat Afib, a specific use outside the FDA’s 510(k) clearance. The letter also stated that the DOJ was investigating whether the Company instructed hospitals to bill Medicare for cardiac surgical ablation using incorrect billing codes. The Company cooperated with the investigation and operated its business in the ordinary course during the investigation. In December 2009 the Company reached a tentative settlement with the DOJ to resolve the investigation and recorded a liability and charged operating expenses for a total of $3,956, which represented the net present value of the proposed settlement amount to be paid to the DOJ, the Relator, and Relator’s counsel (total payments based on the settlement inclusive of interest were estimated to be $4,350, payable over five years).

The settlement was finalized pursuant to the preliminary terms in February 2010, and the Company entered into a settlement agreement with the DOJ, the Office of the Inspector General (“OIG”), and the Relator in the qui tam complaint discussed below. The settlement agreement definitively resolved all claims related to the DOJ investigation. The Company did not admit nor will it admit to any wrongdoing in connection with the settlement. As of June 30, 2013 the Company had made $2,575 in payments (including interest), and had a liability related to this settlement totaling $1,736, of which $1,364 was classified as current.

As part of the resolution, the Company also entered into a five year Corporate Integrity Agreement with the OIG. This agreement acknowledges the existence of the Company’s corporate compliance program and provides for certain other compliance-related activities during the five year term of the agreement. Those activities include specific written standards, monitoring, training, education, independent review, disclosure and reporting requirements.

The Company may, from time to time, become a party to additional legal proceedings.

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Fair Value - Assumptions Used for Estimating Fair Value of Level 3 Liabilities (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Expected volatility of stock	69.00%	70.00%
Dividend yield	0.00%	0.00%
Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk free interest rate	1.26%	0.74%
Expected life of option (years)	4 years 7 months 10 days	5 years 1 month 6 days
Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Risk free interest rate	0.20%	0.23%
Expected life of option (years)	1 year 3 months	1 year 9 months

XML

Equity Compensation Plans - Summary of Share-Based Compensation Expense Related to Employee Share-Based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	$ 820	$ 1,141	$ 1,338	$ 1,829
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	69	68	127	134
Research and Development Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	59	92	100	132
Selling, General and Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense related to employees	$ 692	$ 981	$ 1,111	$ 1,563

XML

Segment and Geographic Information

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Segment and Geographic Information

10. SEGMENT AND GEOGRAPHIC INFORMATION

The Company considers reporting segments in accordance with FASB ASC 280, “Segment Reporting”. The Company develops, manufactures, and sells devices designed primarily for the surgical ablation of cardiac tissue and systems designed for the exclusion of the left atrial appendage. These devices are developed and marketed to a broad base of medical centers in the United States and internationally. Management considers all such sales to be part of a single reportable segment.

Geographic revenue was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
United States	$	15,454	$	13,411	$	30,093	$	26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

Revenue by product type was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
Revenue:	2013		2012		2013		2012
Open-heart	$	9,154	$	8,386	$	18,275	$	16,873
Minimally Invasive		3,511		3,264		6,643		6,212
AtriClip		2,789		1,761		5,175		3,520
Total United States		15,454		13,411		30,093		26,605
International		4,975		4,857		9,766		9,139
Total	$	20,429	$	18,268	$	39,859	$	35,744

The majority of the Company’s long-lived assets are located in the United States.

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Indebtedness

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Indebtedness

6. INDEBTEDNESS

The Company has had a debt agreement with Silicon Valley Bank (“SVB”) since May 1, 2009. The agreement, as amended, restated and modified, includes a $10,000 term loan which matures on February 2, 2017 and a $10,000 revolving credit facility which matures on April 30, 2014. The agreement, as amended, restated and modified, contains covenants that include, among others, covenants that limit the Company’s and its subsidiaries’ ability to dispose of assets, enter into mergers or acquisitions, incur indebtedness, incur liens, pay dividends or make distributions on the Company’s capital stock, make investments or loans, and enter into certain affiliate transactions, in each case subject to customary exceptions for a credit facility of this size and type. Additional covenants apply when the Company has outstanding borrowings under the revolving loan facility or when the Company achieves specific covenant milestones. Financial covenants under the credit facility, as amended, include a minimum EBITDA, a limitation on capital expenditures, and a minimum liquidity ratio. Further, a minimum fixed charge ratio applies when the Company achieves specific covenant milestones. None of the specific covenant milestones have been met as of June 30, 2013. The occurrence of an event of default could result in an increase to the applicable interest rate by 3.0%, an acceleration of all obligations under the Agreement, an obligation of the Company to repay all obligations in full and a right by SVB to exercise all remedies available to it under the Agreement and related agreements including the Guaranty and Security Agreement.

Effective January 30, 2013 the Company and SVB entered into a Joinder and Loan Modification Agreement and an Export-Import Bank Joinder and Loan Modification Agreement which set forth certain amendments to the Company’s credit facility with the Bank. These Modification Agreements added the Company’s wholly-owned subsidiary, AtriCure, LLC, as a borrower, and such Loan Modification Agreement modified the Company’s timing for submitting a forecast to the Bank and decreased the EBITDA amount the Company must achieve to meet the minimum EBITDA covenant.

Effective March 29, 2013 the Company and SVB entered into a Loan Modification Agreement and an Export-Import Bank Loan Modification Agreement which set forth certain amendments to the Company’s credit facility with the Bank. These Modification Agreements provide for (i) a change in the applicable borrowing rate on the revolving credit facility from 0.25% to 1.25% above the prime rate based on the Company’s Liquidity Ratio to the prime rate during a Streamline Period and prime plus 1.25% during a Non-Streamline Period, (ii) a reduction in the collateral handling fee on the revolving credit facility, (iii) a reduction in the fixed interest rate on the term loan from 6.75% to 4.75% and (iv) modifications to the Liquidity Ratio and EBITDA financial covenants. The interest rate was 4.75% as of June 30, 2013 and 6.75% as of June 30, 2012.

As of June 30, 2013 the Company had no borrowings under the revolving credit facility and had borrowing availability of approximately $7,957. As of December 31, 2012 the Company had no borrowings under its revolving credit facility and borrowing availability of $5,303. As of June 30, 2013 and December 31, 2012, $7,333 and $8,333, respectively, was outstanding under the term loan, which included $2,000 classified as current maturities of long-term debt. The effective interest rate on borrowings under the modified term loan, including debt issuance costs, was 6.5%. The Company has an outstanding letter of credit of €75 issued to its European subsidiary’s corporate credit card program provider which will expire on June 30, 2015. No letters of credit were outstanding at December 31, 2012. As of and for the period ended June 30, 2013, the Company was in compliance with all of the financial covenants of the amended and modified credit facility. In addition, if the guarantee by the Export-Import Bank of the United States ceases to be in full force and effect, the Company must repay all loans under the Export-Import agreement.

As of June 30, 2013 the Company had capital leases for computer and office equipment that expire at various terms through 2016, and the cost of the assets under lease was $226. These assets are depreciated over their estimated useful lives, which equal the terms of the leases. Accumulated amortization on the capital leases was $142 at June 30, 2013.

Maturities on long-term debt, including capital lease obligations, are as follows:

2013	$	1,015	July 1, 2013 through December 31, 2013
2014		2,032
2015		2,026
2016		2,016
2017		333
Total	$	7,422

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Description of Business and Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Description of Business and Summary of Significant Accounting Policies

1. DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Nature of the Business—AtriCure, Inc. (the “Company” or “AtriCure”) was incorporated in the State of Delaware on October 31, 2000. The Company provides innovative Atrial Fibrillation (“Afib”) solutions designed to produce superior outcomes that reduce the economic and social burden of Afib. The Company sells its products to hospitals globally through a direct sales force and distributors.

Basis of Presentation—The accompanying interim financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”). The accompanying interim financial statements are unaudited, but in the opinion of the Company’s management, contain all of the normal, recurring adjustments considered necessary to present fairly the financial position, results of operations and cash flows for the periods presented in conformity with generally accepted accounting principles generally accepted in the United States (“GAAP”) applicable to interim periods. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted or condensed. The Company believes the disclosures herein are adequate to make the information presented not misleading. Results of operations are not necessarily indicative of the results expected for the full fiscal year or for any future period.

The accompanying Condensed Consolidated Financial Statements should be read in conjunction with the audited financial statements of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012 filed with the SEC.

Principles of Consolidation—The Condensed Consolidated Financial Statements include the accounts of the Company, AtriCure, LLC, the Company’s wholly-owned subsidiary organized in the State of Delaware, and AtriCure Europe B.V. (“AtriCure Europe”), the Company’s wholly-owned subsidiary incorporated in the Netherlands. All intercompany accounts and transactions have been eliminated in consolidation.

Cash and Cash Equivalents—The Company considers highly liquid investments with maturities of three months or less at the date of acquisition as cash equivalents.

Investments—The Company places its investments primarily in U.S. Government agencies and securities, corporate bonds and commercial paper. The Company classifies all investments as available-for-sale. Investments with maturities of less than one year are classified as short-term investments. Investments are recorded at fair value, with unrealized gains and losses recorded as accumulated other comprehensive income (loss). The Company recognizes gains and losses when these securities are sold using the specific identification method and includes them in interest income or expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss.

Revenue Recognition—The Company accounts for revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, “Revenue Recognition” (“ASC 605”). The Company determines the timing of revenue recognition based upon factors such as passage of title, payment terms and ability to return products. The Company recognizes revenue when all of the following criteria are met: (i) there is persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured.

Revenue is generated from the sale of the Company’s surgical devices. The Company’s surgical devices consist primarily of individual disposable handpieces and equipment generators. The Company’s customers need the combination of the generator and the handpieces to have a functional system. The Company believes that the generator and handpiece are considered a single unit of accounting under ASC 605 because neither the generator nor handpiece have value to the customer on a standalone basis. Therefore, because the customer needs both the generator and handpiece to have a functional system, revenue is recognized upon the later of delivery of the generator or the handpiece.

Pursuant to the Company’s standard terms of sale, revenue is recognized when title to the goods and risk of loss transfers to customers and there are no remaining obligations that will affect the customers’ final acceptance of the sale. Generally, the Company’s standard terms of sale define the transfer of title and risk of loss to occur upon shipment to the respective customer. The Company generally does not maintain any post-shipping obligations to the recipients of the products. No installation, calibration or testing of this equipment is performed by the Company subsequent to shipment to the customer in order to render it operational.

Revenue includes shipping and handling revenue of $197 and $187 for the three months ended June 30, 2013 and 2012, respectively, and $389 and $377 for the six months ended June 30, 2013 and 2012, respectively. Cost of freight for shipments made to customers is included in cost of revenue. Sales and other value-added taxes collected from customers and remitted to governmental

authorities are excluded from revenue. The Company sells its products primarily through a direct sales force, with certain international markets sold through distributors. Terms of sale are generally consistent for both end-users and distributors except that payment terms are generally net 30 days for end-users and net 60 days for distributors.

Sales Returns and Allowances—The Company maintains a provision for sales returns and allowances to account for potential returns of defective or damaged products, products shipped in error and price adjustments. The Company estimates such provision quarterly based primarily on a specific identification basis, in addition to estimating a general reserve. Increases to the provision result in a reduction of revenue. The provision is included in accrued liabilities in the Condensed Consolidated Balance Sheets.

Allowance for Doubtful Accounts Receivable—The Company evaluates the collectability of accounts receivable in order to determine the appropriate reserve for doubtful accounts. In determining the amount of the reserve, the Company considers aging of account balances, historical credit losses, customer-specific information and other relevant factors. An increase to the allowance for doubtful accounts results in a corresponding increase in expense. The Company reviews accounts receivable and adjusts the allowance based on current circumstances and charges off uncollectible receivables against the allowance when all attempts to collect the receivable have failed. The Company’s history of write-offs against the allowance has not been significant.

Inventories—Inventories are stated at the lower of cost or market using the first-in, first-out cost method (“FIFO”) and consist of raw materials, work in process and finished goods. The Company’s industry is characterized by rapid product development and frequent new product introductions. Uncertain timing of product approvals, variability in product launch strategies and variation in product utilization all impact excess and obsolete inventory. An inventory reserve based on product usage is estimated and recorded quarterly for excess, slow moving and obsolete inventory, as well as inventory with a carrying value in excess of its net realizable value. Write-offs are recorded when a product is destroyed. The Company’s history of write-offs against the reserve has not been significant.

Inventories consist of the following:

	June 30, 2013		December 31, 2012
Raw materials	$	2,269	$	3,066
Work in process		760		675
Finished goods		2,999		1,977
Inventories	$	6,028	$	5,718

Property and Equipment—Property and equipment is stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method of depreciation for financial reporting purposes and applied over the estimated useful lives of the assets. The estimated useful life by major asset category is the following: machinery and equipment is three to seven years, computer and other office equipment is three years, furniture and fixtures is three to seven years and leasehold improvements and equipment leased under a capital lease are the shorter of their useful life or remaining lease term. The Company reassesses the useful lives of property and equipment annually, and assets are retired if they are no longer being used. Maintenance and repair costs are expensed as incurred.

Included in property and equipment are generators and other capital equipment (such as the Company’s switchbox units and cryosurgical consoles) that are loaned at no cost to direct customers that use the Company’s disposable products. These generators are depreciated over a period of one to three years, which approximates their useful lives, and such depreciation is included in cost of revenue. The estimated useful lives of this equipment are based on anticipated usage by our customers and the timing and impact of expected new technology rollouts by the Company. To the extent the Company experiences changes in the usage of this equipment or introductions of new technologies, the estimated useful lives of this equipment may change in a future period. Depreciation related to these generators was $299 and $357 for the three months ended June 30, 2013 and 2012, respectively, and $569 and $673 for the six months ended June 30, 2013 and 2012, respectively. As of June 30, 2013 and December 31, 2012, the net carrying amount of loaned equipment included in net property and equipment in the Condensed Consolidated Balance Sheets was $2,441 and $2,197, respectively.

Impairment of Long-Lived Assets—The Company reviews property and equipment annually for impairment using its best estimates based on reasonable and supportable assumptions and projections.

Intangible Assets—Intangible assets with determinable useful lives are amortized on a straight-line basis over the estimated periods benefited, which range from four to eight years.

Other Income—Other income consists primarily of foreign currency transaction gains and losses, grant income and non-employee option gains and losses related to the fair market value change for fully vested options outstanding for consultants which are accounted for as free-standing derivatives. The Company recorded foreign currency transaction gains (losses) of $11 and ($39) for the three months ended June 30, 2013 and 2012, respectively, and $56 and ($35) for the six months ended June 30, 2013 and 2012, respectively, in connection with settlements of its intercompany balance with AtriCure Europe.

The Company periodically is awarded grants to support research and development activities. The Company recognizes grant income when the funds are earned. The Company recorded grant income of $0 and $201 during the three months ended June 30, 2013 and 2012, respectively. Grant income of $0 and $262 was recorded for the six month periods ended June 30, 2013 and 2012, respectively.

The Company historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. Because the non-employee options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the options to be partially net-cash settled, these options, when vested, are no longer eligible for equity classification and are, thus, subsequently accounted for as derivative liabilities under FASB ASC 815, “Derivatives and Hedging” (“ASC 815”) until the awards are ultimately either exercised or forfeited. Accordingly, the vested non-employee options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the three months ended June 30, 2013 and 2012, $28 and ($37), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options. During the six months ended June 30, 2013 and 2012, $42 and ($74), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these fully vested stock options.

Taxes—Income taxes are computed using the asset and liability method in accordance with FASB ASC 740, “Income Taxes” (“ASC 740”), under which deferred income taxes are provided for the temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities. Deferred taxes are measured using provisions of currently enacted tax laws. A valuation allowance against deferred tax assets is recorded when it is more likely than not that such assets will not be fully realized. Tax credits are accounted for as a reduction of income taxes in the year in which the credit originates.

The Company’s estimate of the valuation allowance for deferred tax assets requires it to make significant estimates and judgments about its future operating results. The Company’s ability to realize the deferred tax assets depends on its future taxable income as well as limitations on their utilization. A deferred tax asset is reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized prior to its expiration. The projections of the Company’s operating results on which the establishment of a valuation allowance is based involve significant estimates regarding future demand for the Company’s products, competitive conditions, product development efforts, approvals of regulatory agencies and product cost. If actual results differ from these projections, or if the Company’s expectations of future results change, it may be necessary to adjust the valuation allowance. In evaluating whether to record a valuation allowance, the applicable accounting standards deem that the existence of cumulative losses in recent years is a significant piece of objectively verifiable negative evidence that must be overcome by objectively verifiable positive evidence to avoid the need to record a valuation allowance. The Company has recorded a full valuation allowance against its net deferred tax assets as it is more likely than not that the benefit of the deferred tax assets will not be recognized in future periods.

A provision of The Patient Protection and Affordable Care Act enacted in 2010, as amended, (the “Patient Act”) requires manufacturers of medical devices to pay a 2.3% excise tax on all U.S. medical device sales beginning in January 2013. The Company’s expense related to the medical device excise tax, which was recorded in cost of revenue, was $128 for the three months ended June 30, 2013 and $248 for the six months ended June 30, 2013.

Net Loss Per Share—Basic and diluted net loss per share is computed in accordance with FASB ASC 260, “Earnings Per Share” (“ASC 260”) by dividing the net loss by the weighted average number of common shares outstanding during the period. Since the Company has experienced net losses for all periods presented, net loss per share excludes the effect of 2,588 and 2,986 options, restricted stock and performance-based shares as of June 30, 2013 and 2012, respectively, because they are anti-dilutive. Therefore the number of shares calculated for basic net loss per share is also used for the diluted net loss per share calculation.

Comprehensive Loss and Accumulated Other Comprehensive Income (Loss)—In addition to net losses, the comprehensive loss includes foreign currency exchange rate adjustments and unrealized gains and losses on investments.

Accumulated other comprehensive income (loss) consisted of the following:

	Unrealized Gains on Short- Term Investments			Foreign Currency Translation Adjustment			Accumulated Other Comprehensive Income (Loss)
Balance as of December 31, 2012	$	1		$	76		$	77
Other comprehensive income before reclassifications		0			(189	)		(189	)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			45			45
Net current-period other comprehensive income		0			(144	)		(144	)
Balance as of March 31, 2013	$	1		$	(68	)	$	(67	)
Other comprehensive income before reclassifications		(1	)		1			0
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			11			11
Net current-period other comprehensive income		(1	)		12			11
Balance as of June 30, 2013	$	0		$	(56	)	$	(56	)

Research and Development—Research and development costs are expensed as incurred. These costs include compensation and other internal and external costs associated with the development and research related to new products or concepts, preclinical studies, clinical trials and the cost of products used in trials and tests.

Share-Based Compensation—The Company follows FASB ASC 718, “Compensation-Stock Compensation” (“ASC 718”) to record share-based compensation for all employee share-based payment awards, including stock options, restricted stock, performance shares and stock purchases related to an employee stock purchase plan, based on estimated fair values. The Company’s share-based compensation expense recognized under ASC 718 for the three months ended June 30, 2013 and 2012 was $820 and $1,141, respectively, and $1,338 and $1,829 for the six months ended June 30, 2013 and 2012, respectively, on a before and after tax basis.

FASB ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s Condensed Consolidated Statement of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures. FASB ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

The Company estimates the fair value of time-based options on the date of grant using the Black-Scholes option-pricing model (“Black-Scholes model”). The Company’s determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price, as well as assumptions regarding a number of highly complex and subjective variables. These variables include but are not limited to the Company’s expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. For non-employee options, the fair value at the date of grant is subject to adjustment at each vesting date based upon the fair value of the Company’s common stock. The fair value of market-based performance option grants is estimated at the date of grant using a Monte-Carlo simulation. The value of the portion of the award that is ultimately expected to vest is recognized as expense over the requisite service periods in our Condensed Consolidated Statements of Operations and Comprehensive Loss. The expense has been reduced for estimated forfeitures.

The Company estimates the fair value of restricted stock based upon the grant date closing market price of the Company’s common stock. The Company’s determination of fair value is affected by the Company’s stock price as well as assumptions regarding the number of shares expected to be granted.

The Company also has an employee stock purchase plan (“ESPP” or the “Plan”) which is available to all eligible employees as defined by the Plan. Under the ESPP, shares of the Company’s common stock may be purchased at a discount. The Company estimates the number of shares to be purchased under the Plan and records compensation expense based upon the fair value of the stock at the beginning of the purchase period using the Black-Scholes model.

The Company has historically issued stock options to non-employee consultants as a form of compensation for services provided to the Company. The Company accounts for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50, “Equity-Based Payments to Non-Employees” (“ASC 505-50”). Because these options do not contain specific performance provisions, there is no measurement date of fair value until the options vest. Therefore, the fair value of the options granted and outstanding prior to their vesting date is remeasured each reporting period.

Fully vested options to acquire 38 shares of common stock held by non-employee consultants remained unexercised as of both June 30, 2013 and December 31, 2012. A liability of $120 and $78 was included in accrued liabilities in the Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012, respectively.

Use of Estimates—The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.

Fair Value Disclosures—The book value of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, short-term investments, short and long-term other assets, accounts payable, accrued expenses, other liabilities and fixed interest rate debt, approximate their fair values. The Company classifies cash and short-term investments in U.S. government agencies and securities as Level 1 within the fair value hierarchy. Accounts receivable, short-term other assets, accounts payable and accrued expenses are also classified as Level 1. The carrying amounts of these assets and liabilities approximate their fair value due to their relatively short-term nature. Other assets and other liabilities are classified as Level 1 within the fair value hierarchy. Cash equivalents and short-term investments in commercial paper are classified as Level 2 within the fair value hierarchy (see Note 3 – “Fair Value” for further information). Fixed interest rate debt fair value is determined by calculating the net present value of future debt payments and is classified as Level 2. Significant unobservable inputs with respect to the fair value measurement of the Level 3 non-employee stock options are developed using Company data. When an input is changed, the Black-Scholes model is updated and the results are analyzed for reasonableness.

XML

Segment and Geographic Information - Summary of Geographic Revenue (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Information About Revenue And Geographic Areas [Line Items]
Revenue	$ 20,429	$ 18,268	$ 39,859	$ 35,744
United States [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue	15,454	13,411	30,093	26,605
International [Member]
Information About Revenue And Geographic Areas [Line Items]
Revenue	$ 4,975	$ 4,857	$ 9,766	$ 9,139

XML

Intangible Assets - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 3	$ 3	$ 6	$ 6
Amortization period			8 years

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Description of Business and Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Summary of Inventories

Inventories consist of the following:

	June 30, 2013		December 31, 2012
Raw materials	$	2,269	$	3,066
Work in process		760		675
Finished goods		2,999		1,977
Inventories	$	6,028	$	5,718

Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive income (loss) consisted of the following:

	Unrealized Gains on Short- Term Investments			Foreign Currency Translation Adjustment			Accumulated Other Comprehensive Income (Loss)
Balance as of December 31, 2012	$	1		$	76		$	77
Other comprehensive income before reclassifications		0			(189	)		(189	)
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			45			45
Net current-period other comprehensive income		0			(144	)		(144	)
Balance as of March 31, 2013	$	1		$	(68	)	$	(67	)
Other comprehensive income before reclassifications		(1	)		1			0
Amounts reclassified from accumulated other comprehensive income to other income on the statement of operations		0			11			11
Net current-period other comprehensive income		(1	)		12			11
Balance as of June 30, 2013	$	0		$	(56	)	$	(56	)

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Equity Compensation Plans

6 Months Ended

Jun. 30, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity Compensation Plans

9. EQUITY COMPENSATION PLANS

The Company has several share-based incentive plans: the 2001 Stock Option Plan (the “2001 Plan”), the 2005 Equity Incentive Plan (the “2005 Plan”) and the 2008 Employee Stock Purchase Plan (the “ESPP”).

2001 Plan and 2005 Plan

The 2001 Plan is no longer used for granting incentives. Under the 2005 Plan, the Board of Directors may grant incentive stock options to employees and any parent or subsidiary’s employees, and may grant nonstatutory stock options, restricted stock, stock appreciation rights, performance units or performance shares to employees, directors and consultants of the Company and any parent or subsidiary’s employees, directors and consultants. The administrator (currently the Compensation Committee of the Board of Directors) has the power to determine the terms of any awards, including the exercise price of options, the number of shares subject to each award, the exercisability of the awards and the form of consideration.

Options granted under the 2001 Plan and the 2005 Plan generally expire ten years from the date of grant. Options granted from the 2001 Plan are generally exercisable beginning one year from the date of grant in cumulative yearly amounts of 25% of the shares granted. Options granted from the 2005 Plan generally vest at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter over the following three years. Restricted stock awards granted under the 2005 Plan vest 25% annually over four years from date of grant.

As of June 30, 2013 6,893 shares of common stock had been reserved for issuance under the 2005 Plan. The shares authorized for issuance under the 2005 Plan include: (a) shares reserved but unissued under the 2001 Plan as of August 10, 2005, (b) shares returned to the 2001 Plan as the result of termination of options or the repurchase of shares issued under such plan, and (c) annual increases in the number of shares available for issuance on the first day of each year equal to the lesser of:

• 3.25% of the outstanding shares of common stock on the first day of the fiscal year;

• 825 shares; or

• an amount the Company’s Board of Directors may determine.

On January 1, 2013 an additional 549 shares were authorized for issuance under the 2005 Plan representing 3.25% of the outstanding shares on that date. As of June 30, 2013 there were 1,755 shares available for future grants under the plans.

Activity under the Plans during the six months ended June 30, 2013 was as follows:

Stock Options	Number of Shares Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at January 1, 2013		3,172		$	8.81
Granted		293			8.73
Exercised		(230	)		5.41
Cancelled or forfeited		(904	)		10.34
Outstanding at June 30, 2013		2,331		$	8.54		6.8	$	3,841
Vested and expected to vest		2,186		$	8.62		6.6	$	3,520
Exercisable at June 30, 2013		1,228		$	9.42		4.5	$	1,508

Restricted Stock	Number of Shares Outstanding			Weighted Average Grant Date Fair Value
Outstanding at January 1, 2013		504		$	7.93
Granted		20			8.92
Released		(84	)		9.44
Forfeited		(183	)		8.21
Outstanding at June 30, 2013		257		$	7.31

The total intrinsic value of options exercised during the three month periods ended June 30, 2013 and 2012 was $135 and $1,093, respectively. The total intrinsic value of options exercised during the six month periods ended June 30, 2013 and 2012 was $599 and $1,244, respectively. As a result of the Company’s tax position, no tax benefit was recognized related to the stock option exercises. For the six month periods ended June 30, 2013 and 2012, respectively, $1,240 and $434 in cash proceeds was included in the Company’s Condensed Consolidated Statements of Cash Flows as a result of the exercise of stock options. The total fair value of performance shares vested during both of the three month periods ended June 30, 2013 and 2012 was $0, and the total fair value of performance shares vested during the six month periods ended June 30, 2013 and 2012 was $0 and $99, respectively. The total fair value of restricted stock vested during the three month periods ended June 30, 2013 and 2012 was $98 and $114, respectively. The total fair value of restricted stock vested during the six month periods ended June 30, 2013 and 2012 was $705 and $724, respectively.

The exercise price per share of each option is equal to the fair market value of the underlying share on the date of grant. The Company issues registered shares of common stock to satisfy stock option exercises and restricted stock grants.

The Company recognized expense related to stock options and restricted stock for the three months ended June 30, 2013 and 2012 of $747 and $1,087, respectively. The Company recognized expense related to stock options and restricted stock for the six months ended June 30, 2013 and 2012 of $1,206 and $1,677, respectively. Incremental compensation expense of $396 was recorded during the second quarter of 2012 due to the modification of share-based compensation of the Company’s former Chief Financial Officer. As of June 30, 2013 there was $8,942 of unrecognized compensation costs related to non-vested stock option and restricted stock arrangements ($6,032 relating to stock options and $2,910 relating to restricted stock). This cost is expected to be recognized over a weighted average period of 3.2 years for stock options and 2.9 years for restricted stock.

The Company awarded 225 performance options to its new President and Chief Executive Officer when he joined the Company in November 2012. The options expire ten years from the date of grant and vest in increments of 25 shares when the volume adjusted weighted average closing price of the common stock of the Company as reported by NASDAQ (or any other exchange on which the common stock of the Company is listed) for 30 consecutive days equals or exceeds each of $10.00 per share, $12.50 per share, $15.00 per share, $17.50 per share, $20.00 per share, $25.00 per share, $30.00 per share, $35.00 per share and $40.00 per share. In accordance with FASB ASC 718, a Monte Carlo simulation was performed to estimate the fair values, vesting terms and vesting probabilities for each tranche of options. Expense calculated using these estimates is being recorded over the estimated vesting terms. The Company recognized expense of $45 related to the performance options during the three months ended June 30, 2013. The Company recognized expense of $83 related to the performance options during the six months ended June 30, 2013. As of June 30, 2013 there was $549 of unrecognized compensation costs related to non-vested performance options. The cost is expected to be recognized over a weighted-average period of 2.45 to 5.22 years. None of the market conditions were met as of June 30, 2013; therefore, none of the performance options were exercisable.

The Company historically issued performance shares to certain employees and consultants to incent and reward them for the achievement of specified performance over various service periods. The participants receive awards for a specified number of shares of the Company’s common stock at the beginning of the award period, which entitles the participants to the shares at the end of the award period if achievement of the specified metrics and service requirements occurs. The Company did not release any performance shares (gross) during the three months ended June 30, 2013 and 2012 related to the participants’ achievement of certain specified metrics. The Company released 0 and 10 performance shares (gross) during the six months ended June 30, 2013 and 2012, respectively, related to the participants’ achievement of certain specified metrics. As of June 30, 2013 the Company has no performance shares outstanding. In accordance with FASB ASC 718, the Company estimates the number of shares to be granted based upon the probability that the performance metric and service period will be achieved. The fair value of the estimated award, based on the market value of the Company’s stock on the date of award, is expensed over the award period. The probability of meeting the specified metrics is reviewed quarterly. The Company recognized no expense related to performance shares during the three months ended June 30, 2013 and 2012 or the six months ended June 30, 2013 and 2012. As of June 30, 2013 there was no unrecognized compensation cost related to non-vested share-based compensation arrangements associated with performance shares.

Employee Stock Purchase Plan (ESPP)

During 2008 the Company established its 2008 Employee Stock Purchase Plan (“ESPP”) which is available to eligible employees as defined in the ESPP. Under the ESPP, shares of the Company’s common stock may be purchased at a discount (currently 15%) of the lesser of the closing price of the Company’s common stock on the first trading day or the last trading day of the offering period. The offering period (currently six months) and the offering price are subject to change. Participants may not purchase more than $25 of the Company’s common stock in a calendar year and, effective January 1, 2009, may not purchase more than 1.5 shares during an offering period. Beginning on January 1, 2009 and on the first day of each fiscal year thereafter during the term of the ESPP, the number of shares available for sale under the ESPP shall be increased by the lesser of (i) two percent (2%) of the Company’s outstanding shares of common stock as of the close of business on the last business day of the prior calendar year, not to exceed 600 shares, or (ii) a lesser amount determined by the Board of Directors. At June 30, 2013 there were 720 shares available for future issuance under the ESPP. Share-based compensation expense with respect to the ESPP was $73 and $54 for the three months ended June 30, 2013 and 2012, respectively. Share-based compensation expense with respect to the ESPP was $132 and $152 for the six months ended June 30, 2013 and 2012, respectively.

Valuation and Expense Information Under FASB ASC 718

The following table summarizes share-based compensation expense related to employee share-based compensation under FASB ASC 718 for the three and six months ended June 30, 2013 and 2012. This expense was allocated as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Cost of revenue	$	69	$	68	$	127	$	134
Research and development expenses		59		92		100		132
Selling, general and administrative expenses		692		981		1,111		1,563
Total share-based compensation expense related to employees	$	820	$	1,141	$	1,338	$	1,829

In calculating compensation expense, the fair value of the options is estimated on the grant date using the Black-Scholes model including the following assumptions:

	Three Months Ended June 30,		Six Months Ended June 30,
	2013	2012	2013	2012
Risk free interest rate	0.75%–1.38%	1.16%–1.21%	0.75%–1.51%	0.85%–1.37%
Expected life of option (years)	5.33–6.91	6.85–7.06	5.31–7.38	5.39–7.14
Expected volatility of stock	69.00%	71.00%	69.00%	71.00%
Weighted-average volatility	69.00%	71.00%	69.00%	71.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%

The Company’s estimate of volatility is based solely on the Company’s trading history. The risk-free interest rate assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life. The Company estimates the expected terms of options using historical employee exercise behavior adjusted for abnormal activity.

The fair value of restricted stock awards is based on the market value of the Company’s stock on the date of the awards.

Based on the assumptions noted above, the weighted average estimated fair value per share of the stock options and restricted stock granted for the respective periods was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Stock options	$	5.52	$	5.34	$	5.50	$	6.20
Restricted stock		8.92		8.21		8.92		9.86

In calculating compensation expense for performance options, the fair value of the options was estimated on the grant date using a Monte Carlo simulation including the following assumptions:

Strike price	$	5.91
Contractual term		10.00
Expected volatility of stock		69.60	%
Expected rate of return		1.75	%
Dividend yield		0.00	%

The contractual term is estimated considering that the performance options were issued to a high ranking executive of the Company and that they will be held until expiration. Expected volatility is estimated based on the Company’s trading history. The expected rate of return assumption is based upon the U.S. treasury yield curve at the time of grant for the expected option life.

Based on the assumptions noted above, the estimated grant date fair value per share of the performance options granted in 2012 was as follows:

	Price Target		Fair Value
Tranche 1	$	10.00	$	4.32
Tranche 2		12.50		4.30
Tranche 3		15.00		4.27
Tranche 4		17.50		4.23
Tranche 5		20.00		4.19
Tranche 6		25.00		4.10
Tranche 7		30.00		4.01
Tranche 8		35.00		3.92
Tranche 9		40.00		3.83

Non-Employee Stock Compensation

The Company historically issued nonstatutory common stock options to consultants to purchase shares of common stock as a form of compensation for services provided to the Company. Such options vest over a service period ranging from immediately to four years. After January 1, 2006 all stock options granted to non-employee consultants have a four year vesting period and vest at a rate of 25% on the first anniversary date of the grant and ratably each month thereafter.

The Company accounts for the options granted to non-employees prior to their vesting date in accordance with ASC 505-50. Because these options do not contain specific performance provisions, there is no measurement date of fair value until the options vest. Therefore, the fair value of the options granted and outstanding prior to their vesting date is remeasured each reporting period. The fair value was determined using the Black-Scholes model. No non-employee stock options have been granted since 2008. The values attributable to the non-vested portion of the non-employee stock options have been amortized over the service period on a graded vesting method and the vested portion of these stock options was remeasured at each vesting date. As of June 30, 2013 all non-employee consultant options were fully vested.

Once these non-employee consultant stock options have vested, the awards no longer fall within the scope of ASC 505-50. Because the stock options require settlement by the Company’s delivery of registered shares and because the tax withholding provisions in the awards allow the stock options to be partially net-cash settled, these vested stock options are no longer eligible for equity classification and are, thus, accounted for as derivative liabilities under FASB ASC 815 until the stock options are ultimately either exercised or forfeited. Accordingly, the vested non-employee consultant stock options are classified as liabilities and remeasured at fair value through earnings at each reporting period. During the three months ended June 30, 2013 and 2012, $28 and ($37), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these stock options. During the six months ended June 30, 2013 and 2012, $42 and ($74), respectively, of expense (income) was recorded as a result of the remeasurement of the fair value of these stock options. As of both June 30, 2013 and December 31, 2012, fully vested stock options to acquire 38 shares of common stock held by non-employee consultants remained unexercised and a liability of $120 and $78 was included in accrued liabilities in the Condensed Consolidated Balance Sheets as of June 30, 2013 and December 31, 2012, respectively.

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Accrued Liabilities (Tables)

6 Months Ended

Jun. 30, 2013

Payables And Accruals [Abstract]

Accrued Liabilities

Accrued liabilities consisted of the following:

	June 30, 2013		December 31, 2012
Accrued commissions	$	1,932	$	1,464
Accrued settlement reserve (current portion)		1,364		1,120
Accrued bonus		911		487
Other accrued liabilities		477		707
Accrued vacation		391		349
Accrued taxes and value-added taxes payable		360		366
Accrued payroll		178		153
Accrued royalty		172		118
Withheld payroll taxes		166		126
Accrued non-employee stock options		120		78
Sales/returns allowance—trade		105		105
Total	$	6,176	$	5,073

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Fair Value (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of June 30, 2013:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	29,464	$	—	$	29,464
Commercial paper		—		2,898		—		2,898
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	32,362	$	—	$	33,362
Liabilities:
Derivative instruments	$	—	$	—	$	120	$	120
Total liabilities	$	—	$	—	$	120	$	120

In accordance with ASC 820, the following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2012:

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)		Total
Assets:
Money market funds	$	—	$	5,261	$	—	$	5,261
Commercial paper		—		3,247		—		3,247
U.S. government agencies and securities		1,000		—		—		1,000
Total assets	$	1,000	$	8,508	$	—	$	9,508
Liabilities:
Derivative instruments	$	—	$	—	$	78	$	78
Total liabilities	$	—	$	—	$	78	$	78

Assumptions Used for Estimating Fair Value of Level 3 Liabilities

The fair value of the Level 3 liabilities is estimated using the Black-Scholes model including the following assumptions:

	As of June 30, 2013	As of December 31, 2012
Risk free interest rate	0.20%–1.26%	0.23%–0.74%
Expected life of option (years)	1.25–4.61	1.75–5.10
Expected volatility of stock	69.00%	70.00%
Dividend yield	0.00%	0.00%

Level 3 Fair Value Measurements Using Significant Other Unobservable Inputs for Derivative Instruments

In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of June 30, 2013:

Beginning Balance–January 1, 2013	$	78
Total gains/losses (realized/unrealized) included in earnings		42
Purchases (exercises)		—
Reclassification from equity to liability when fully vested		—
Ending Balance–June 30, 2013	$	120
Losses included in earnings (or changes in net assets attributable to the change in unrealized gains relating to assets held at reporting date)	$	(42	)

In accordance with ASC 820, the following table represents the Company’s Level 3 fair value measurements using significant other unobservable inputs for derivative instruments as of December 31, 2012:

Beginning Balance–January 1, 2012	$	208
Total gains/losses (realized/unrealized) included in earnings		(179	)
Purchases (exercises)		(50	)
Reclassification from equity to liability when fully vested		99
Ending Balance–December 31, 2012	$	78
Gains included in earnings (or changes in net assets attributable to the change in unrealized losses relating to assets held at reporting date)	$	179

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Document and Entity Information	6 Months Ended
	Jun. 30, 2013	Jul. 26, 2013
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Entity Registrant Name	AtriCure, Inc.
Entity Central Index Key	0001323885
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		20,980,093

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Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2013

Goodwill And Intangible Assets Disclosure [Abstract]

Summary of Company's Intangible Assets with Definite Lives

The following table provides a summary of the Company’s intangible assets with definite lives:

	Non- Compete Agreement
Net carrying amount as of December 31, 2011	$	45
Amortization		(13	)
Net carrying amount as of December 31, 2012		32
Amortization		(6	)
Net carrying amount as of June 30, 2013	$	26

Estimated Future Amortization Expense Related to Intangible Assets with Definite Lives

Estimated future amortization expense related to intangible assets with definite lives is as follows:

Year	Amortization
2013	$	7
2014		12
2015		7
Total	$	26