Prospectus Supplement No. 17 (to Prospectus dated May 30, 2013) Filed pursuant to Rule 424 (b)(4) Registration No. 333-187508

125,000 Shares of Series A Convertible Preferred Stock

12,500,000 Shares of Common Stock Underlying the Preferred Stock

Warrants to Purchase up to 6,250,000 Shares of Common Stock and

6,250,000 Shares of Common Stock Underlying the Warrants

ARCA biopharma, Inc.

This prospectus supplement supplements the prospectus dated May 30, 2013 (the “Prospectus”), as supplemented by that certain Prospectus Supplement No. 1 dated July 17, 2013 (“Supplement No. 1”), by that certain Prospectus Supplement No. 2 dated July 19, 2013 (“Supplement No. 2”), by that certain Prospectus Supplement No. 3 dated July 24, 2013 (“Supplement No. 3”), by that certain Prospectus Supplement No. 4 dated July 30, 2013 (“Supplement No. 4”), by that certain Prospectus Supplement No. 5 dated August 6, 2013 (“Supplement No. 5”), by that certain Prospectus Supplement No. 6 dated September 4, 2013 (“Supplement No. 6”), by that certain Prospectus Supplement No. 7 dated September 23, 2013 (“Supplement No. 7”), by that certain Prospectus Supplement No. 8 dated October 29, 2013 (“Supplement No. 8”), by that certain Prospectus Supplement No. 9 dated November 6, 2013 (“Supplement No. 9”), by that certain Prospectus Supplement No. 10 dated November 13, 2013 (“Supplement No. 10”), by that certain Prospectus Supplement No. 11 dated November 21, 2013 (“Supplement No. 11”), by that certain Prospectus Supplement No. 12 dated December 5, 2013 (“Supplement No. 12”), by that certain Prospectus Supplement No. 13 dated January 8, 2014 (“Supplement No. 13”), by that certain Prospectus Supplement No. 14 dated February 10, 2014 (“Supplement No. 14”), by that certain Prospectus Supplement No. 15 dated February 12, 2014 (“Supplement No. 15”), and by that certain Prospectus Supplement No. 16 dated February 18, 2014 (“Supplement No. 16”, and together with Supplement No. 1, Supplement No. 2, Supplement No. 3, Supplement No. 4, Supplement No. 5, Supplement No. 6, Supplement No. 7, Supplement No. 8, Supplement No. 9, Supplement No. 10, Supplement No. 11, Supplement No. 12, Supplement No. 13, Supplement No. 14, and Supplement No. 15, the “Supplements”), which form a part of our Registration Statement on Form S-1 (Registration No. 333-187508). This prospectus supplement is being filed to update and supplement the information in the Prospectus and the Supplements with the information contained in our current report on Form 8-K, filed with the Securities and Exchange Commission (the “Commission”) on March 3, 2014 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus, the Supplements and this prospectus supplement relate to the offer and sale of up to 125,000 shares of Series A Convertible Preferred Stock (“Preferred Stock”) which are convertible into 12,500,000 shares of Common Stock, warrants to purchase up to 6,250,000 shares of our Common Stock and 6,250,000 shares of Common Stock underlying the warrants.

This prospectus supplement should be read in conjunction with the Prospectus and the Supplements. This prospectus supplement updates and supplements the information in the Prospectus and the Supplements. If there is any inconsistency between the information in the Prospectus, the Supplements and this prospectus supplement, you should rely on the information in this prospectus supplement.

Our common stock is traded on the Nasdaq Global Market under the trading symbol “ABIO.” On March 3, 2014, the last reported sale price of our common stock was $1.85 per share.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” beginning on page 5 of the Prospectus and beginning on page 23 of our quarterly report on Form 10-Q for the quarterly period ended September 30, 2013 before you decide whether to invest in shares of our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if the Prospectus or this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is March 3, 2014

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): March 3, 2014 (February 27, 2014)

ARCA biopharma, Inc.

(Exact Name of Registrant as Specified in Charter)

Delaware	000-22873	36-3855489
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

11080 CirclePoint Road, Suite 140, Westminster, CO 80020

(Address of Principal Executive Offices) (Zip Code)

(720) 940-2200

(Registrant’s Telephone Number, Including Area Code)

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

Bonuses, Base Salaries and Equity Grants

On February 27, 2014, the Compensation Committee (the “Committee”) of the Board of Directors of ARCA biopharma, Inc. (the “Company”), approved cash bonuses (the “Bonuses”) for each of the executive officers of the Company in the amounts set forth below, payable on or around March 7, 2014. The Committee also approved the base salaries for the Company’s “named executive officers” (as defined in Item 402(a)(3) of Regulation S-K promulgated by the Securities and Exchange Commission), in each case as set forth below.

Name and Title	2014 Cash Bonus		Base Salary
Michael R. Bristow President and Chief Executive Officer	$	60,050	$	281,139
Patrick M. Wheeler Chief Financial Officer	$	46,650	$	268,975
Christopher D. Ozeroff Senior Vice President, General Counsel	$	35,200	$	274,773

The Committee determined the Bonuses are to be paid in recognition of the past efforts of each of the executives. The new base salaries will become effective on March 1, 2014.

On February 27, 2014, the Compensation Committee also approved the following stock option (“Options”) and restricted stock unit (“RSUs”) grants to the below executive officers pursuant to the Company’s 2013 Equity Incentive Plan and the forms of Stock Option Grant Notice, Option Agreement, Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement for officers, as filed with the Securities and Exchange Commission as exhibits to the Company’s Current Report on Form 8-K on September 23, 2013:

Name	Options Granted (1)		RSU’s Granted (2)
Michael Bristow President and Chief Executive Officer		51,500		56,700
Christopher Ozeroff Senior Vice President, General Counsel & Secretary		10,500		34,200
Patrick Wheeler Chief Financial Officer		20,500		34,200

(1) Vests in 48 equal monthly installments measured from February 27, 2014

(2) Vests in 4 equal annual installments measured from February 27, 2014

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 hereunto duly authorized.

Dated: March 3, 2014

ARCA biopharma, Inc. (Registrant)
By:	/s/ Patrick M. Wheeler
	Name: Patrick M. Wheeler
	Title: Chief Financial Officer