ARCA BIOPHARMA , I NC .
F IRST A MENDMENT TO N OTE AND W ARRANT P URCHASE A GREEMENT
T HIS F IRST A MENDMENT TO N OTE AND W ARRANT P URCHASE A GREEMENT (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.
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
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