Exhibit 10.14

ARCA BIOPHARMA, INC.

FIRST AMENDMENT
TO NOTE AND WARRANT PURCHASE AGREEMENT

THIS FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT(this Amendment) is
made and entered into as of October 10, 2008 by and between ARCA biopharma, Inc., a Delaware corporation (the Company), the undersigned Purchasers (individually, a Purchaser and collectively, the
Purchasers) and Parent.

RECITALS

A. The Company has authorized the sale of its 6% convertible promissory notes due March 31, 2009 and warrants to purchase shares of the Companys capital stock.

B. The Company and the Purchasers have entered into that certain Note and Warrant Purchase Agreement, dated September 24, 2008 (the
Purchase Agreement) pursuant to which the Purchasers agreed to purchase the Notes at the Closing. Capitalized terms used, but not defined herein, shall have the meanings assigned to them in the Purchase Agreement.

C. Section 5.7 of the Purchase Agreement allows the Company, a majority of the Principal Series Preferred Stockholders (as such term is defined in
the Restated Charter) and, for so long as the Merger Agreement remains in full force and effect, Parent, to amend the Purchase Agreement.

D. The Company, the undersigned Purchasers, who represent at least a majority of the Principal Series Preferred Stockholders (as such term is defined in the Restated Charter), and Parent, desire to amend the Purchase Agreement as
provided below.

AMENDMENT

NOW, THEREFORE, in consideration of the above recitals and the mutual covenants contained herein, the parties hereby agree as follows:

1.
Section 1.2 of the Purchase Agreement is hereby deleted in its entirety and replaced with the following language:

1.2 Issuance of Warrants.Subject to the terms of this Agreement, and for the additional
consideration (the Warrant Consideration) set forth opposite such Purchasers name on the Schedule of Purchasers under the heading Warrant Consideration, the Company shall issue to each Purchaser a warrant
to purchase shares of Common Stock of the Company. Subject to certain adjustments provided in the warrant, each warrant issuable pursuant to this Section 1.2 shall entitle the Purchaser to acquire the number of shares equal to the quotient of
(a) one-fifth (1/5th) of such Purchasers total purchase price (Total Purchase Price) set forth opposite such



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Purchasers name on the Schedule of Purchasers under the heading Total PurchasePrice) divided by (b) the exercise
price of each warrant, rounded up to the nearest share. The warrants shall be in substantially the form attached hereto as Exhibit B (each, a Warrant and collectively, the Warrants).

2. Section 1.4 of the Purchase Agreement is hereby deleted in its entirety and replaced with the following language:

1.4 Delivery.At the Closing: (a) each Purchaser will deliver to the Company a check or wire transfer funds in the total amount of such
Purchasers Total Purchase Price, (b) the Company shall issue and deliver to each Purchaser a Note in favor of such Purchaser payable in the principal amount of such Purchasers Loan Amount and a Warrant, and (c) the Company
shall execute and deliver such other documents as the Purchasers shall reasonably require in order to consummate the transactions contemplated herein. In connection with the Closing, the Company shall have filed with the Delaware Secretary of State
the Certificate of Amendment to the Restated Charter (as defined below) in substantially the form attached hereto as Exhibit C (the Charter Amendment).

3. The Schedule of Purchasers attached to the Purchase Agreement is hereby replaced in its entirety with the Schedule of Purchasers attached hereto as Exhibit A.

4. Except as expressly amended by this Amendment, the Purchase Agreement shall remain in full force and effect without change.

5. This Amendment may be executed in any number of counterparts, each of which when executed and delivered shall be an original, but all of which together shall
constitute one and the same instrument.

[signature pages follow]



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IN WITNESS WHEREOF,the parties have executed this
AMENDMENTas of the date first written above.



|                     |  |                                                                   |  |                                                            |  |                              |  |                                      
|-------------------- |  | ----------------------------------------------------------------- |  | ---------------------------------------------------------- |  | ---------------------------- |  | -------------------------------------
|COMPANY:             |  |                                                                   |  | PURCHASERS:                                               
|                     |  |                                                                  
|ARCA BIOPHARMA, INC. |  |                                                                   |  | SKYLINE VENTURE PARTNERS QUALIFIED PURCHASER FUND IV, L.P.
|                     |  |                                                                   |  |                                                           
|Signature:           |  | /s/ Christopher D. Ozeroff                                        |  |                                                            |  | By:                          |  | Skyline Venture Management IV, LLC   
|Print Name:          |  | Christopher D. Ozeroff                                            |  |                                                            |  |                              |  | Its General Partner                  
|Title:               |  | Executive Vice President Business Development and General Counsel |  |                                                            |  | By:                          |  | /s/ John G. Freund                   
|                     |  |                                                                   |  |                                                            |  |                              |  | John G Freund, Managing Director     
|                     |  |                                                                   | 
|                     |  |                                                                   |  |                                                            |  | INTERWEST PARTNERS IX, LP   
|                     |  |                                                                   |  |                                                           
|                     |  |                                                                   |  |                                                            |  | By:                          |  | InterWest Management Partners IX, LLC
|                     |  |                                                                   |  |                                                           
|                     |  |                                                                   |  |                                                            |  | By:                          |  | /s/ Linda Grais                      
|                     |  |                                                                   |  |                                                            |  |                              |  | Linda Grais, Venture Member          
|                     |  |                                                                   | 
|                     |  |                                                                   |  |                                                            |  | ATLAS VENTURE FUND VII, L.P.
|                     |  |                                                                   |  |                                                           
|                     |  |                                                                   |  |                                                            |  | By:                          |  | Atlas Venture Associates VII, L.P.   
|                     |  |                                                                   |  |                                                            |  |                              |  | its General Partner                  
|                     |  |                                                                   |  |                                                           
|                     |  |                                                                   |  |                                                            |  | By:                          |  | Atlas Venture Associates VII, Inc.   
|                     |  |                                                                   |  |                                                            |  |                              |  | its General Partner                  
|                     |  |                                                                   |  |                                                           
|                     |  |                                                                   |  |                                                            |  | Signature:                   |  | /s/ Kristen Laguerre                 
|                     |  |                                                                   |  |                                                            |  | Print Name:                  |  | Kristen Laguerre                     
|                     |  |                                                                   |  |                                                            |  | Title:                       |  | Vice President                       

FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT

SIGNATURE PAGE



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| |  |  |  |  |  |                                   |  |                                            
| |  |  |  |  |  | --------------------------------- |  | -------------------------------------------
| |  |  |  |  |  | BOULDER VENTURES IV, L.P.        
| |  |  |  | 
| |  |  |  |  |  | By:                               |  | BV Partners IV, L.L.C., its General Partner
| |  |  |  | 
| |  |  |  |  |  | Signature:                        |  | /s/ Kyle Lefkoff                           
| |  |  |  |  |  | Print Name:                       |  | Kyle Lefkoff                               
| |  |  |  |  |  | Title:                            |  | Managing Member                            
| |  |  | 
| |  |  |  |  |  | BOULDER VENTURES IV (ANNEX), L.P.
| |  |  |  | 
| |  |  |  |  |  | By:                               |  | BV Partners IV, L.L.C., its General Partner
| |  |  |  | 
| |  |  |  |  |  | Signature:                        |  | /s/ Kyle Lefkoff                           
| |  |  |  |  |  | Print Name:                       |  | Kyle Lefkoff                               
| |  |  |  |  |  | Title:                            |  | Managing Member                            
| |  |  | 
| |  |  |  |  |  | THE PEIERLS FOUNDATION, INC.     
| |  |  |  | 
| |  |  |  |  |  | Signature:                        |  | /s/ E. Jeffrey Peierls                     
| |  |  |  |  |  | Print Name:                       |  | E. Jeffrey Peierls                         
| |  |  |  |  |  | Title:                            |  | President                                  
| |  |  | 
| |  |  |  |  |  | NUVELO, INC.                     
| |  |  |  | 
| |  |  |  |  |  | Signature:                        |  | /s/ Lee Bendekgey                          
| |  |  |  |  |  | Print Name:                       |  | Lee Bendekgey                              
| |  |  |  |  |  | Title:                            |  | Sr. VP, CFO and General Counsel            

FIRST AMENDMENT TO NOTE AND WARRANT PURCHASE AGREEMENT

SIGNATURE PAGE



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SCHEDULE OF PURCHASERS



|                                                                                                       |  |             |              |                      |   |                     |  |   |             
|------------------------------------------------------------------------------------------------------ |  | ----------- | ------------ | -------------------- | - | ------------------- |  | - | ------------
|NAME AND ADDRESS                                                                                       |  | LOAN AMOUNT |              | WARRANTCONSIDERATION |   | TOTAL PURCHASEPRICE
|SKYLINE VENTURE PARTNERS QUALIFIED PURCHASER FUND IV, L.P.                                             |  | $           | 1,742,362    |                      | $ | 83,334              |  | $ | 1,825,696   
|525 University Ave Suite 520 Palo Alto, CA 94301 Attention: Kerry Kenny Facsimile: (650) 329-1090      |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|INTERWEST PARTNERS IX, LP                                                                              |  | $           | 1,395,144    |                      | $ | 66,728              |  | $ | 1,461,872   
|2710 Sand Hill Road Second Floor Menlo Park, CA 94025 Attention: Linda Grais Facsimile: (650) 854-4706 |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|ATLAS VENTURE FUND VII, L.P.                                                                           |  | $           | 3,506,900    |                      | $ | 167,730             |  | $ | 3,674,630   
|890 Winter Street, Suite 320 Waltham, MA 02451 Attention: General Counsel Facsimile: (781) 622-1701    |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|BOULDER VENTURES IV, L.P.                                                                              |  | $           | 88,176       |                      | $ | 4,217               |  | $ | 92,393      
|1900 Ninth Street, Suite 200 Boulder, CO 80302 Attention: Kyle Lefkoff Facsimile: (303) 444-0267       |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|BOULDER VENTURES IV (ANNEX), L.P.                                                                      |  | $           | 1,331,715    |                      | $ | 63,694              |  | $ | 1,395,409   
|1900 Ninth Street, Suite 200 Boulder, CO 80302 Attention: Kyle Lefkoff Facsimile: (303) 444-0267       |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|THE PEIERLS FOUNDATION, INC.                                                                           |  | $           | 286,306      |                      | $ | 13,694              |  | $ | 300,000     
|c/o U.S. Trust Company of N.Y. 114 West 47thStreet New York, NY 10036 Attention: Mr. John Kennedy      |  |             |              |                      |   |                     |  |   |             
|                                                                                                       |  |             |             
|TOTAL                                                                                                  |  | $           | 8,350,603.00 |                      | $ | 399,397.00          |  | $ | 8,750,000.00