SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* FORMELA JEAN FRANCOIS (Last) (First) (Middle) C/O ATLAS VENTURE 25 FIRST STREET, SUITE 303 (Street) CAMBRIDGE MA 02141 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol ARCA biopharma, Inc. [ ABIO ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 10/22/2012
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/22/2012		A		317,379	A	$0.3939	1,579,542(1)	I	See Foonote(1)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Common Stock Warrants (right to buy)	$0.3001	10/22/2012		A		238,034		10/25/2012(2)	10/25/2017	Common Stock	238,034	$0	313,483	I	See Footnote(3)

Explanation of Responses:

1. Includes 1,262,163 shares of Common Stock held by Atlas Venture Fund VII, L.P. prior to the reported transaction. Atlas Venture Associates VII, L.P. or AVA VII, L.P. is the sole general partner of AV VII. Each Atlas VII and AVA VII LP disclaims beneficial ownership of such shares except to the extent of it's pecuniary interest therein. Dr. Formela is a Partner with Atlas Venture and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

2. The warrants are fully vested and exercisable upon issuance and have a contractual term of 5 years.

3. Includes warrants to purchase 75449 shares of common stock held by Atlas Venture Fund VII, L.P. prior to the reported transaction. Atlas Venture Associates VII, L.P. or AVA VII, L.P. is the sole general partner of AV VII. Each Atlas VII and AVA VII LP disclaims beneficial ownership of such shares except to the extent of it's pecuniary interest therein. Dr. Formela is a Partner with Atlas Venture and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

	/s/ Frank Castellucci, Attorney-in-Fact	10/24/2012
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.