FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Keuer Thomas A   2. Issuer Name and Ticker or Trading Symbol ARCA biopharma, Inc. [ABIO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) ARCA BIOPHARMA, INC., 11080 CIRCLEPOINT ROAD, SUITE 140 3. Date of Earliest Transaction (Month/Day/Year) 09/18/2015 (Street) WESTMINSTER, CO 80020 4. If Amendment, Date 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 (City) (State) (Zip) 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 09/18/2015   S   680 (1) D $ 6.33 17,407 (2) D

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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 Underlying Securities (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 of Derivative Security: 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

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Keuer Thomas A ARCA BIOPHARMA, INC. 11080 CIRCLEPOINT ROAD, SUITE 140 WESTMINSTER, CO 80020			Chief Operating Officer

Signatures

/s/ Thomas A. Keuer		09/21/2015
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	Represents shares of common stock sold pursuant to a Rule 10b5-1 Plan adopted by the Reporting Person for satisfaction of their tax withholding obligation with respect to the vesting of previously reported Restricted Stock Units ("RSUs") granted to the Reporting Person under the Issuer's 2013 Equity Incentive Plan (the "Plan").
(2)	Includes (i) remaining 2,143 previously reported shares issued as RSUs under the Plan that vests on 9/17/16, (ii) remaining 2,857 previously reported shares issued as RSUs under the Plan that vests in two equal installments beginning on 10/15/15, (iii) 3,664 previously reported shares issued as RSUs under the Plan that vest in three equal annual installments beginning on 2/27/16, and (iv) 3,621 previously reported shares issued as RSUs under the Plan that vest in three equal annual installments beginning April 2, 2016, provided that the Reporting Person's continuous service to the Issuer has not been terminated as defined under the Plan; and 5,122 previously reported shares of common stock owned.

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