July 16, 2024

Thomas A. Keuer
President and Chief Operating Officer
ARCA biopharma, Inc.
10170 Church Ranch Way, Suite 100
Westminster, CO 80021

       Re: ARCA biopharma, Inc.
           Amendment No. 2 to Registration Statement on Form S-4
           Filed July 9, 2024
           File No. 333-279387
Dear Thomas A. Keuer:

       We have reviewed your amended registration statement and have the
following comment.

       Please respond to this letter by amending your registration statement
and providing the
requested information. If you do not believe the comment applies to your facts
and circumstances
or do not believe an amendment is appropriate, please tell us why in your
response.

       After reviewing any amendment to your registration statement and the
information you
provide in response to this letter, we may have additional comments. Unless we
note otherwise,
any references to prior comments are to comments in our July 3, 2024 letter.

Amendment No. 2 to Registration Statement on Form S-4
Opinion of Lucid, ARCA's Financial Advisor, to ARCA's Board of Directors, page
112

1.     We note your disclosure that Lucid, in connection with its opinion,
"[r]eviewed and
       analyzed certain internal financial analyses, including . . .
projections as to cost and
       expenses . . . and other information concerning Oruka prepared by
Oruka[.]" Please
       disclose these financial projections and discuss the material
assumptions and limitations
       underlying the financial projections or, alternatively, please explain
why such disclosures
       are not required pursuant to Item 4(b) of Form S-4 and Item 1015(b)(6)
of Regulation M-
       A.
 July 16, 2024
Page 2

       Please contact Jenn Do at 202-551-3743 or Daniel Gordon at 202-551-3486
if you have
questions regarding comments on the financial statements and related matters.
Please contact
Tamika Sheppard at 202-551-8346 or Joshua Gorsky at 202-551-7836 with any other
questions.



                                                         Sincerely,

                                                         Division of
Corporation Finance
                                                         Office of Life
Sciences
cc:   Brent D. Fassett