SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* VENROCK HEALTHCARE CAPITAL PARTNERS LP (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 06/16/2015	3. Issuer Name and Ticker or Trading Symbol ARCA biopharma, Inc. [ ABIO ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	10,789,324	I(1)(3)	By funds

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Warrants (right to buy)	12/13/2015	06/16/2022	Common Stock	4,315,730	$0.8716	I(2)(3)	By funds

1. Name and Address of Reporting Person* VENROCK HEALTHCARE CAPITAL PARTNERS LP (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Venrock Healthcare Capital Partners II, L.P. (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VHCP Co-Investment Holdings, LLC (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VHCP Co-Investment Holdings II, LLC (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Koh Bong Y (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Hove Anders D (Last) (First) (Middle) C/O VENROCK 530 FIFTH AVENUE (Street) NEW YORK NY 10036 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VHCP Management, LLC (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* VHCP Management II, LLC (Last) (First) (Middle) C/O VENROCK 3340 HILLVIEW AVE. (Street) PALO ALTO CA 94304 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Consists of: 2,736,388 shares held directly by Venrock Healthcare Capital Partners, L.P. ("VHCP"); 5,373,623 shares held directly by Venrock Healthcare Capital Partners II, L.P. ("VHCP II"); 500,409 shares held directly by VHCP Co-Investment Holdings, LLC ("Co-Invest"); and 2,178,904 shares held directly by VHCP Co-Investment Holdings II, LLC ("Co-Invest II").

2. Consists of: 1,094,555 warrants held directly by VHCP; 2,149,449 warrants held directly by VHCP II; 200,164 warrants held directly by Co-Invest; and 871,562 warrants held directly by Co-Invest II.

3. VHCP Management, LLC ("VHCP Management") is the general partner of VHCP and the manager of Co-Invest and may be deemed to beneficially own these shares. VHCP Management II, LLC ("VHCP Management II") is the general partner of VHCP II and the manager of Co-Invest II and may be deemed to beneficially own these shares. Drs. Anders D. Hove and Bong Y. Koh are the managing members of VHCP Management and VHCP Management II and may be deemed to beneficially own these shares. Drs. Hove and Koh, VHCP Management and VHCP Management II expressly disclaim beneficial ownership over these shares and warrants except to the extent of their indirect pecuniary interests therein.

Remarks:

	/s/ David L. Stepp, Authorized Signatory	06/17/2015
	/s/ David L. Stepp, as attorney in fact	06/17/2015
	/s/ David L. Stepp, as attorney in fact	06/17/2015
	** Signature of Reporting Person	Date
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