SecProbe.io

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 Document O’Melveny & Myers LLP Two Embarcadero Center 28ᵗʰ Floor San Francisco, CA 94111-3823 T: +1 415 984 8700 F: +1 415 984 8701 omm.com August 6, 2025 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Industrial Applications and Services 100 F Street, N.E. Washington, D.C. 20549 Attention: Tracey Houser Terence O’Brien Juan Grana Katherine Bagley Re: Heartflow, Inc. Amendment No. 1 to Registration Statement on Form S-1 Filed August 1, 2025 File No. 333-288733 To the addressees set forth above: On behalf of our client, Heartflow, Inc., a Delaware corporation (the “ Company ”), we hereby submit to the staff (the “ Staff ”) of the Securities and Exchange Commission (the “ Commission ”) this letter setting forth the Company’s response to the comment contained in the Staff’s letter dated August 5, 2025, regarding the above-referenced Amendment No. 1 to Registration Statement on Form S-1, as filed via EDGAR to the Commission on August 1, 2025 (the “ Registration Statement ”). Concurrently with the submission of this letter, the Company is filing its revised registration statement on Form S-1 (the “ Revised Registration Statement ”) and certain exhibits via EDGAR to the Commission for review. The changes reflected in the Revised Registration Statement include those made in response to the comment of the Staff set forth in the Staff’s letter of August 5, 2025. For the Staff’s convenience, we have reproduced below the comment from the Staff in bold italics, followed by the corresponding response. We have included references to pages in the Revised Registration Statement where the language addressing the comment appears. Capitalized terms used in this letter and not otherwise defined herein have the meanings ascribed to them in the Revised Registration Statement. Austin  •  Century City  •  Dallas  •  Houston  •  Los Angeles  •  Newport Beach  •  New York  •  San Francisco  •  Silicon Valley  •  Washington, DC Beijing  •  Brussels  •  Hong Kong  •  London  •  Seoul  •  Shanghai  •  Singapore  •  Tokyo General 1. We note your revised disclosure in response to comment 2. Please revise to disclose the natural person(s) with voting and dispositive control over the shares held by each of BCLS Fund III Investments, LP; Hayfin Services, LLP; and the Wellington Entities, or provide us with your legal analysis as to why you are not required to do so. Response: In response to the Staff’s comment, the Company has revised the disclosure on page 189. In addition, the Company has been informed by BCLS Fund III Investments, LP that: With respect to the securities held by BCLS Fund III Investments, LP, no natural person is the beneficial owner of such securities for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, and Rule 13d-3 promulgated thereunder. As described under “Principal stockholders” on page 188 of the Revised Registration Statement, Bain Capital Life Sciences Investors, LLC is the ultimate general partner of BCLS Fund III Investments, LP. Footnote 1 to the beneficial ownership table on page 188 of the Registration Statement was previously revised to state that voting and investment decisions with respect to securities held by BCLS Fund III Investments, LP are made by the partners of Bain Capital Investors, LLC, of whom there are three or more and none of whom individually has the power to direct such decisions. Further, the Company has been informed by the Wellington Entities of the following: Wellington Management Company LLP (“Wellington Management”) is the investment adviser to two entities that own shares of common stock of the Company (each a “Wellington Entity”), and which are specifically named in the footnotes to the beneficial ownership table contained in the Registration Statement. As noted in the disclosure, Wellington Management, a registered investment adviser under the Investment Advisers Act of 1940, as amended, is the investment adviser to each Wellington Entity, and Wellington Alternative Investments LLC is general partner to each Wellington Entity. Wellington Management Investment, Inc. is the managing member of Wellington Alternative Investments LLC. Wellington Management is an indirect subsidiary of Wellington Management Group LLP. Under Regulation 13D-G and Section 13(d) of the Exchange Act, Wellington Management Group LLP (“WMG”) and Wellington Management may be deemed beneficial owners with shared voting and investment power over the shares held by each Wellington Entity. Wellington Management, however, has communicated that it believes that it is not appropriate for Wellington Management or WMG to list a natural person who exercises sole or shared voting or dispositive powers with respect to each Wellington Entity. Wellington Management has indicated that it has discussed this issue with the Staff on previous occasions, including in connection with Form S-3 registration statements filed by Provident Bankshares Corporation (File No. 333-125230), IBERIABANK Corporation (File No. 333-139984) and Suffolk Bancorp (File No. 333-184530). Wellington Management has indicated that the Staff agreed with the analysis set forth in those letters. Wellington Management has confirmed to the Company that the statements in such letters remain accurate as they relate to each Wellington Entity. For your convenience, Wellington Management’s 2 previous analysis is summarized below: Wellington Management’s structure and de-centralized approach to investment management does not lend itself to specifying a particular individual that has beneficial ownership. Wellington Management does not have a Chief Investment Officer or any group of individuals who give “top down” direction with respect to investment positions or strategies for portfolios that Wellington Management manages. Because numerous portfolio managers, assisted by others, make investment and voting decisions for the client accounts, beneficial ownership should not be attributed to any single individual within Wellington Management. Further, the Company has been informed by Hayfin Services, LLP (“Hayfin”) of the following: Each Hayfin entity that has a beneficial interest in shares of the Company’s common stock issuable upon conversion of its redeemable convertible preferred stock or the 2025 Convertible Notes or subject to exercisable warrants is structured as a limited partnership acting by its general partner. The names of such entities and their respective general partners are included in the added disclosure on page 189. As noted in the disclosure, while a general partner entity may be deemed to share voting and investment power over the Company securities held by the limited partnership for which it acts as general partner, in all cases decisionmaking on the exercise of voting and investment power with respect to such securities requires a majority of the board members of its general partner, and no single board member has the power to direct such decisions. Hayfin has communicated to the Company that it believes that it is not appropriate to list a natural person who exercises voting or dispositive power with respect to each Hayfin entity in footnote 3 to the “Principal stockholders” table in the Revised Registration Statement. Hayfin has indicated that it is aware of at least one prior occasion in connection with the S-1 registration statement filed by Surgalign Holdings, Inc. (File No. 333-251828) where the Staff did not require the Company to identify natural persons exercising voting or dispositive power. Hayfin’s structure and approach to investment management do not lend themselves to specifying a particular individual that has beneficial ownership. Hayfin does not have a Chief Investment Officer who gives “top down” direction with respect to investment positions or strategies for funds portfolios that Hayfin manages. Accordingly, beneficial ownership should not be attributed to any single individual within Hayfin. We believe that this analysis is consistent with Section 13(d) of the Exchange Act and Regulation 13D-G as well as the Staff’s long-standing interpretations and publicly expressed positions with respect to those regulations. For example, the no-action letter issued to Southland Corporation on August 10, 1987 has been held out as the Staff’s view that if voting or investment power is held by more than one individual in an entity and those individuals may act only by majority vote and not separately, then the individuals would not be deemed to be beneficial owners of the shares held by that entity. Finally, providing disclosure of natural persons for the Hayfin entities does not provide investors with any additional meaningful information. *                                             *                                             * We appreciate the Staff’s comment and request that the Staff contact the undersigned at (415) 984-8943 or rcoombs@omm.com with any questions or comments regarding this letter and/or the Revised Registration Statement. 3 Sincerely, /s/ Ryan Coombs Ryan Coombs O’Melveny & Myers LLP cc: John C.M. Farquhar, Chief Executive Officer, Heartflow, Inc. Vikram Verghese, Chief Financial Officer, Heartflow, Inc. Angela Ahmad, Chief Legal and Compliance Officer, Heartflow, Inc. Shelly Heyduk, O’Melveny & Myers LLP Dave Peinsipp, Cooley LLP Kristin VanderPas, Cooley LLP Denny Won, Cooley LLP Charles S. Kim, Cooley LLP 4

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<TEXT>
 August 5, 2025

John C.M. Farquhar
Chief Executive Officer
Heartflow, Inc.
331 E. Evelyn Avenue
Mountain View, CA 94041

 Re: Heartflow, Inc.
 Amendment No. 1 to Registration Statement on Form S-1
 Filed August 1, 2025
 File No. 333-288733
Dear John C.M. Farquhar:

 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 a 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 issued on July 29,
2025.

Amendment No. 1 to Registration Statement on Form S-1 filed August 1, 2025
General

1. We note your revised disclosure in response to comment 2. Please revise
to disclose
 the natural person(s) with voting and dispositive control over the
shares held by each
 of BCLS Fund III Investments, LP; Hayfin Services, LLP; and the
Wellington
 Entities, or provide us with your legal analysis as to why you are not
required to do
 so.
 August 5, 2025
Page 2

 Please contact Tracey Houser at 202-551-3736 or Terence O'Brien at
202-551-3355 if
you have questions regarding comments on the financial statements and related
matters. Please contact Juan Grana at 202-551-6034 or Katherine Bagley at
202-551-2545
with any other questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Industrial
Applications and
 Services
cc: Ryan Coombs, Esq.
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 Document   HEARTFLOW, INC. 331 E. Evelyn Avenue Mountain View, California 94041 August 5, 2025 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549-6010 Attention: Tracey Houser Terence O'Brien Juan Grana Katherine Bagley Re: Request for Effectiveness for Heartflow, Inc. Registration Statement on Form S-1 (File No. 333-288733) To the addressees set forth above: In accordance with Rule 461 of Regulation C of the General Rules and Regulations under the Securities Act of 1933, as amended, we hereby request acceleration of the effective date of the Registration Statement on Form S-1 (Registration No. 333-288733) (as amended, the “ Registration Statement ”) of Heartflow, Inc. (the “ Company ”). We respectfully request that the Registration Statement become effective as of 4:00 p.m., Washington, D.C. time, on August 7, 2025, or as soon as practicable thereafter, or at such other time thereafter as our counsel, O’Melveny & Myers LLP may request by telephone. Once the Registration Statement has been declared effective, please orally confirm that event with our counsel, O’Melveny & Myers LLP, by calling Shelly Heyduk at (949) 823-7968 or Ryan Coombs at (415) 984-8943. Thank you for your assistance in this matter. If you have any questions or comments regarding the foregoing, please do not hesitate to contact Ms. Heyduk or Mr. Coombs at the telephone numbers above. Very truly yours, HEARTFLOW, INC. By: /s/ Vikram Verghese Vikram Verghese Chief Financial Officer cc: John C.M. Farquhar, Chief Executive Officer, Heartflow, Inc. Angela Ahmad, Chief Legal and Compliance Officer, Heartflow, Inc. Shelly Heyduk, O’Melveny & Myers LLP Ryan Coombs, O’Melveny & Myers LLP Dave Peinsipp, Cooley LLP Kristin VanderPas, Cooley LLP Denny Won, Cooley LLP Charles S. Kim, Cooley LLP

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 Document August 5, 2025 United States Securities and Exchange Commission Division of Corporation Finance Office of Industrial Applications and Services 100 F Street, N.E. Washington, DC 20549 Attn: Tracey Houser Terence O’Brien Juan Grana Katherine Bagley Re: Heartflow, Inc. (the “Registrant”) Registration Statement on Form S-1, as amended (File No. 333-288733) Request for Acceleration Ladies and Gentlemen: Pursuant to Rule 460 of the General Rules and Regulations under the Securities Act of 1933, as amended, we wish to advise that between August 1, 2025 and the date hereof, approximately 550 copies of the Preliminary Prospectus, dated August 1, 2025, were distributed to prospective underwriters, institutional investors and prospective dealers in connection with the above-captioned Registration Statement, as amended. We wish to advise you that the participating underwriters have informed us that they have complied and will continue to comply with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended. We hereby join in the request of the Registrant that the effectiveness of the above-captioned Registration Statement, as amended, be accelerated to 4:00 p.m. Eastern Time, on Thursday, August 7, 2025 or as soon thereafter as practicable. [signature page follows] Very truly yours, J.P. MORGAN SECURITIES LLC MORGAN STANLEY & CO. LLC PIPER SANDLER & CO. As representatives of the Underwriters J.P. MORGAN SECURITIES LLC By: /s/ Benjamin Burdett Name: Benjamin Burdett Title: Managing Director, Head of Healthcare ECM MORGAN STANLEY & CO. LLC By: /s/ Eleni Apostolatos Name: Eleni Apostolatos Title: Vice President PIPER SANDLER & CO. By: /s/ Neil Riley Name: Neil Riley Title: Managing Director [Signature Page to Acceleration Request Letter]

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<TEXT>
 April 28, 2025

John C.M. Farquhar
Chief Executive Officer
Heartflow, Inc.
331 E. Evelyn Avenue
Mountain View, CA 94041

 Re: Heartflow, Inc.
 Amendment No. 2 to Draft Registration Statement on Form S-1
 Submitted April 18, 2025
 CIK No. 0001464521
Dear John C.M. Farquhar:

 We have reviewed your amended draft registration statement and have the
following
comments.

 Please respond to this letter by providing the requested information and
either
submitting an amended draft registration statement or publicly filing your
registration
statement on EDGAR. If you do not believe a comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why
in your
response.

 After reviewing the information you provide in response to this letter
and your
amended draft registration statement or filed registration statement, we may
have additional
comments. Unless we note otherwise, any references to prior comments are to
comments in
our April 10, 2025 letter.

Amendment No. 2 to Draft Registration Statement on Form S-1
Risk Factors
We face risks associated with a concentrated customer base., page 23

1. We note your response to comment 5. Please revise to explain how "the
decision-
 making function for some of [your] accounts is concentrated in a
relatively small
 number of customers," and advise whether you expect new accounts to come
from
 current or new customers going forward. Please also clarify how you
determine an
 account is "new," given your disclosure that decision-making for
accounts is
 concentrated in a relatively small number of customers.
 April 28, 2025
Page 2

Management's Discussion and Analysis of Financial Condition and Results of
Operations
Components of our results of operations, page 84

2. We note your revised disclosure that "new accounts generally take 12
months to reach
 steady state revenue case volumes." Please revise to clarify the case
volumes you
 consider to be "steady state," and explain the significance of this fact
to your business
 and operations.
3. You disclose that "[r]evenue cases generated from clinic or office-based
accounts
 typically carry a lower pricing than hospital-based accounts,
commensurate with their
 lower reimbursement levels," and that you "expect the percentage of
[y]our revenue
 cases generated from clinic or office-based accounts to increase over
time." You also
 disclose that your revenue has fluctuated, and you expect it to continue
to fluctuate
 based on, among other things, changes in the mix of customer accounts.
To provide
 context for investors regarding your pricing, revenue, and customer mix,
please clarify
 the percentage of your installed base attributable to clinic or
office-based accounts
 compared to hospital-based accounts for the financial periods presented
in the filing.
Results of operations, page 86

4. We note your revised analysis of revenue in response to comment 6. As
requested,
 please quantify the impact the three factors discussed had on revenue
for fiscal year
 2024 as compared to fiscal year 2023. Refer to Item 303(b)(2) of
Regulation S-K and
 Section 501.12.b.3. of the Financial Reporting Codification (i.e.,
Release 33-8350,
 Section III.B.3.) for guidance.
5. We note your disclosure on page 88 that "[t]he gross margin increase
during the year
 ended December 31, 2024 was primarily driven by increased revenues and
through
 the launch of a major new algorithm that significantly increased the
automation of
 manual components of the production teams process, which lowered the
cost of
 revenue per analysis." Please revise to briefly discuss the new
algorithm. Further, as
 requested in comment 7, please quantify the impact the increase in
revenue and the
 launch of a new algorithm had on the increase in gross margin for fiscal
year 2024
 compared to fiscal year 2023. Refer to Item 303(b)(2) of Regulation S-K
and Section
 501.12.b.3. of the Financial Reporting Codification (i.e., Release
33-8350, Section
 III.B.3.) for guidance.
Liquidity and capital resources
Sources of liquidity, page 89

6. We note in response to comment 8 that you intend to disclose your cash
balance as of
 March 31, 2025. In addition, please expand your disclosures to provide
investors with
 a discussion of the material factors that have impacted and will
continue to impact
 your liquidity from a short-term and long-term perspective.
Specifically, we note that
 as of December 31, 2024 in comparison to December 31, 2023, when you
concluded
 that there was substantial doubt about your ability to continue as a
going concern,
 your working capital has decreased, the degree to which total
liabilities exceeds total
 assets has increased, total stockholders deficit has increased, you
continue to
 recognize loss from operations and net loss, and that you expect to
"continue to incur
 losses and expend significant amounts of cash in the foreseeable
future." This
 April 28, 2025
Page 3

 discussion should bridge the gap between these negative factors and your
conclusion
 that your cash balance is sufficient to meet all of your cash
obligations within the next
 12 months and explain how you intend to address your ongoing liquidity
needs over
 the long-term and the implications if you are unable to meet those
long-term liquidity
 needs. Refer to Item 303(b)(1) of Regulation S-K and Section 501.13 of
the Financial
 Reporting Codification (i.e., Release 33-8350, Section IV) for guidance.
Business
Our Heartflow FFRCT Analysis, page 120

7. We note your response to comment 9. Please tell us how the PRECISE trial
supports
 your disclosure that NITs are inaccurate a majority of the time, and
often result in
 either missed CAD diagnoses or unnecessary invasive procedures, and
revise your
 disclosure accordingly.
 Please contact Tracey Houser at 202-551-3736 or Terence O'Brien at
202-551-3355 if
you have questions regarding comments on the financial statements and related
matters. Please contact Juan Grana at 202-551-6034 or Katherine Bagley at
202-551-2545
with any other questions.

 Sincerely,

 Division of
Corporation Finance
 Office of
Industrial Applications and
 Services
cc: Ryan Coombs, Esq.
</TEXT>
</DOCUMENT>

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<TEXT>
 April 10, 2025

John C.M. Farquhar
Chief Executive Officer
Heartflow, Inc.
331 E. Evelyn Avenue
Mountain View, CA 94041

 Re: Heartflow, Inc.
 Amendment No. 1 to Draft Registration Statement on Form S-1
 Submitted March 27, 2025
 CIK No. 0001464521
Dear John C.M. Farquhar:

 We have reviewed your amended draft registration statement and have the
following
comments.

 Please respond to this letter by providing the requested information and
either
submitting an amended draft registration statement or publicly filing your
registration
statement on EDGAR. If you do not believe a comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why
in your
response.

 After reviewing the information you provide in response to this letter
and your
amended draft registration statement or filed registration statement, we may
have additional
comments. Unless we note otherwise, any references to prior comments are to
comments in
our March 5, 2025 letter.

Amendment No. 1 to Draft Registration Statement on Form S-1
Prospectus Summary
Overview, page 1

1. We note your disclosure in response to comment 3, including that your
Heartflow
 FFRct Analysis "calculates blood flow and pinpoints clinically
significant CAD,
 which is CAD with a fractional flow reserve value of .80 or below."
Please revise
 your disclosure to define and explain at first instance the significance
of "fractional
 flow reserve" with respect to coronary artery disease.
2. We note your response to comment 7, including that "all of the
approximately 0.4
 million patients with acute chest pain with NSTE...will be eligible for
[y]our
 April 10, 2025
Page 2

 Heartflow Plaque Analysis." Please revise to briefly explain why you
believe that all
 of these patients will be eligible for your Heartflow Plaque Analysis.
The Offering, page 13

3. We note your disclosure that $98.4 million of convertible promissory
notes will
 automatically convert with the initial public offering. We also note
that $23 million of
 outstanding indebtedness under the 2024 Credit Agreement was converted
into 2025
 Convertible Notes. Please revise your disclosure to include these
additional 2025
 Convertible Notes.
Risk factors
If we are unable to design, implement and maintain effective internal control
over financial
reporting..., page 62

4. We note that you previously included a risk factor detailing identified
material
 weaknesses in your internal control over financial reporting, the
material adjustments
 to your fiscal year 2023 financial statements as a result of these
material weaknesses,
 along with adjustments made to your fiscal years 2019 through 2022
financial
 statements, and the remediation steps that have been implemented to
address the
 material weaknesses. Please expand your risk factor to discuss the
previously
 identified material weaknesses, the remediation steps implemented for
the identified
 material weaknesses, and the status of your testing of your remediation
efforts.
We face risks associated with a concentrated customer base, page 62

5. We note your revised disclosure in response to comment 13, including
that for the
 year ended December 31, 2024, your top two largest customers
collectively
 represented approximately 8% of your revenue, and that as you expand the
adoption
 of the Heartflow Platform to new accounts, your customer concentration
risk may
 increase. Please clarify why the addition of new accounts may increase
your customer
 concentration, including whether you expect current customers to open
new accounts,
 and if so, the impact of the same on your growth strategies. Please also
explain how
 you determine an account is "new," given your disclosure that
decision-making for
 accounts is concentrated in a relatively small number of customers.
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Results of operations, page 86

6. Please expand your discussion and analysis of revenue to quantify the
impact of the
 change in utilization and pricing, including the impact of rebates and
the change in
 mix of customer accounts. Also, provide an explanation for the changes
in mix of
 customer accounts. Refer to Item 303(b)(2) of Regulation S-K for
guidance.
7. Please expand your discussion and analysis of gross margin to quantify
the impact of
 the increase in revenue versus the automation of manual components of
the
 production teams process. Refer to Item 303(b)(2) of Regulation S-K
and Section
 501.12 of the Financial Reporting Codification (i.e., Release 33-8350,
Section III.B)
 for guidance.
 April 10, 2025
Page 3
Liquidity and capital resources
Sources of liquidity, page 88

8. We note that you no longer believe that there is substantial doubt about
your ability to
 continue as a going concern as of December 31, 2024 due to the 2025
Convertible
 Notes offering during the first quarter of fiscal year 2025. We further
note that as of
 December 31, 2024, your working capital has decreased, the degree to
which total
 liabilities exceeds total assets has increased, total stockholders
deficit has increased,
 and you continue to recognize loss from operations and net loss that you
expect will
 continue into the future. As such, please expand your disclosures to
provide investors
 with a balanced outlook about the material factors that have impacted
and will
 continue to impact your liquidity from a short-term and long-term
perspective. Also
 provide a discussion about why the 2025 Convertible Notes issuances
provide you
 with sufficient liquidity to meet all of your obligations within the
next 12 months,
 including the amount of the net proceeds received from the issuances
along with how
 the net proceeds were utilized. Refer to Item 303(b)(1) of Regulation
S-K and Section
 501.13 of the Financial Reporting Codification (i.e., Release 33-8350,
Section IV) for
 guidance.
Business
Our Clinical Results and Economic Evidence, page 119

9. We note your response to comment 23, including the revised disclosures
on pages 119
 through 126. Please revise to disclose whether statistical significance
was
 demonstrated, including supporting p-values, as appropriate, for all of
the studies
 cited, specifically the PRECISE and PLATFORM studies. Please also expand
upon
 the "usual care" pathways noted in the PRECISE trial, and explain how
your
 PRECISE trial demonstrated that "NITs are inaccurate a majority of the
time, and
 often result in either missed CAD diagnoses or unnecessary invasive
procedures," as
 disclosed on page 125.
Certain Relationships and Related-Party Transactions, page 162

10. We note your response to comment 26, including your disclosure on page
166 that
 "[c]ertain of [y]our obligations under the BCLS Letter Agreement will
remain in
 effect after the completion of this offering, including [y]our
obligation to obtain the
 consent of Bain Capital prior to making certain public disclosures about
Bain Capital
 or certain of its affiliates, certain indemnification obligations and
certain pro rata lock-
 up release rights of Bain Capital." Please revise to further discuss
these
 indemnification obligations and pro-rata lock-up release rights.
18. Subsequent Events, page F-39

11. Please expand your disclosure for the 2025 Convertible Notes to disclose
the net
 proceeds and effective interest rate.
 April 10, 2025
Page 4

 Please contact Tracey Houser at 202-551-3736 or Terence O'Brien at
202-551-3355 if
you have questions regarding comments on the financial statements and related
matters. Please contact Juan Grana at 202-551-6034 or Katherine Bagley at
202-551-2545
with any other questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Industrial
Applications and
 Services
cc: Ryan Coombs, Esq.
</TEXT>
</DOCUMENT>

March 5, 2025
John C.M. Farquhar
Chief Executive Officer
Heartflow, Inc.
331 E. Evelyn Avenue
Mountain View, CA 94041
Re:Heartflow, Inc.
Draft Registration Statement on Form S-1
Submitted February 6, 2025
CIK No. 0001464521
Dear John C.M. Farquhar:
            We have reviewed your draft registration statement and have the following comments.
            Please respond to this letter by providing the requested information and either
submitting an amended draft registration statement or publicly filing your registration
statement on EDGAR. If you do not believe a comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
            After reviewing the information you provide in response to this letter and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Draft Registration Statement on Form S-1 submitted February 6, 2025
Cover Page
1.We note your disclosure on page 62 that, after this offering, certain of your executive
officers, directors, owners of more than 5% of your capital stock, and their affiliates
will have the ability to influence you through their ownership position, including the
potential ability to determine all matters requiring stockholder approval. Please revise
your cover page to include disclosure describing the control of these shareholders and
affiliates.
Prospectus Summary, page 1
Here and throughout your registration statement where you provide disclosure
regarding the industry in which you operate, your competitors, and market statistics, 2.

March 5, 2025
Page 2
please provide support for your disclosures, including, as applicable, the basis for
management's opinions or beliefs. For example only, we note the following
statements:

•"We estimate that there were approximately 9.5 million non-invasive tests
(“NITs”) in the United States in 2023 for patients experiencing stable or acute
chest pain, which we refer to as symptomatic CAD patients;"
•Stress-based NITs are "inaccurate, a majority of the time, and often result in either
missed CAD diagnoses or unnecessary invasive procedures;" "approximately 20-
50% of patients who undergo stress-based NITs go home with false negative or
undetected CAD;" and "up to 55% of patients receive false positives;"
•"We estimate that as of December 31, 2023, there were approximately 2,700
hospitals and outpatient facilities in the United States that perform CCTA, and
this target account base has grown at a 10% CAGR from 2018 to 2023;" and
•"With the elevation of CCTA to a Class 1, Level A guideline recommendation by
the AHA and ACC guidelines in 2021, CCTA test volumes have grown at a 22%
CAGR from 2018 to 2023 while SPECT volumes have grown at a 2% CAGR
over the same time period."

Please make conforming changes throughout your filing, including to your description
of your business, competition, and the industry in which you operate.
Overview, page 1
3.We note your disclosure on page 2 that "Heartflow FFRCT Analysis calculates blood
flow and pinpoints functionally significant CAD at every point in the major coronary
arteries, guiding decisions on whether a patient requires invasive revascularization."
Please define "functionally significant."
4.We note your disclosure on page 3 that "[t]he CCTA + Heartflow FFRCT Analysis
pathway is supported by the American Heart Association (“AHA”) and American
College of Cardiology (“ACC”) guidelines, with CCTA identified as a Class 1, Level
A test and Heartflow FFRCT Analysis identified as a Class 2a, Level B test,"
"Heartflow FFRCT Analysis is reimbursed under a dedicated Category 1 Current
Procedural Terminology (“CPT”) code," and "A Category 1 CPT code was also
recently established for Heartflow Plaque Analysis, which will take effect in January
2026, and it is covered by all seven Medicare administrative contractor (“MACs”)."
Please revise your disclosure here or provide a cross reference to more detailed
disclosure in the filing to further explain the various classes, levels and reimbursement
categories pursuant to current clinical guidelines and reimbursement policies,
including those of the AHA and ACC. We also note your disclosure on page 103
that "CCTA now has guideline support from the European Society of Cardiology
Clinical Practice guidelines on Chronic Coronary Syndromes (1B), is included in the
National Institute for Health and Care Excellence (“NICE”) guidelines in the United
Kingdom, and in the Japanese Circulation Society (“JCS”) 2022 Guidelines in Japan."
Please revise to discuss the significance of receiving guideline support from each of
these institutions.

March 5, 2025
Page 3
5.We note your disclosure on page 22 that the Heartflow Platform relies on a CCTA
first being performed, and that companies performing CCTA could determine to
develop, partner with, or acquire and offer a product that competes with the Heartflow
Platform, or manufacture CT scanners that are no longer compatible with the
Heartflow Platform. Please revise your summary to discuss the Heartflow Platform's
reliance on third-party CCTAs and compatible CT scanners, including any risks or
limitations related to this reliance.
6.Please revise to disclose your accumulated deficit for the fiscal years ended December
31, 2024 and 2023.
Our symptomatic CAD market opportunity, page 5
We note that you discuss estimates for your market opportunity in the United States
throughout your filing. Please address the following issues related to your market
opportunity estimates:

•You disclose on page 2 that you estimate your current market opportunity in the
United States is approximately $5 billion, and that you believe "Heartflow FFRCT
Analysis is applicable to approximately 33% of NIT patients annually and the
majority of patients experiencing acute chest pain, which represents 3.1 million
patients and an estimated market opportunity of approximately $3.3 billion in the
United States." Please provide support for your statements regarding the number
of patients "experiencing acute chest pain," including sources for this information
and clarify how you arrived at a market opportunity of $3.3 billion based on this
estimate. Include a discussion of the material assumptions underlying your
estimates, including price per product, reimbursement rates, etc.
•As a related matter, we note your disclosure on page 5 that "Heartflow FFRCT
Analysis is reimbursed for use on any CCTA showing 40% to 90% stenosis,
which [you] estimate to be approximately 33% of all CCTAs annually," and that
you "believe that CCTA + Heartflow FFRCT Analysis therefore is applicable to
33% of the NIT market and a majority of patients experiencing acute chest pain,
which represents 3.1 million patients and an estimated market opportunity of
approximately $3.3 billion in the United States." Please provide the data, sources,
and assumptions underlying your estimates of stenosis, patients, and market
opportunity and explain how you calculated an estimated market opportunity in
the US of approximately $3.3 billion based on these estimates. Please also clarify
whether your estimated market opportunity is based on patients with a CCTA
showing 40% to 90% stenosis, or "a majority of patients experiencing acute chest
pain."
You disclose that "[w]e believe our Heartflow Plaque Analysis is applicable to
approximately 60% of NIT patients annually and the majority of patients
experiencing acute chest pain, which represents 5.5 million patients and an
estimated market opportunity of an incremental approximately $1.7 billion in the
United States." Please provide the data and assumptions supporting your estimates
related to the proportion of NIT patients and number of patients disclosed. In
addition, please discuss how your "limited market education efforts" for •7.

March 5, 2025
Page 4
Heartflow Plaque Analysis impact your market opportunity estimates for this
product.
8.We note your disclosure that your current focus is on the United States but that you
"also have a commercial presence and regulatory approval in certain international
markets, including the United Kingdom, European Union and Japan, which [you]
estimate represents an additional 4.2 million potential CCTA patients." Please provide
relevant sources, data, and assumptions supporting your estimate of the potential
CCTA patients in these international markets.
The Offering, page 12
9.We note your disclosure that "[i]n connection with the completion of this offering,
[you] are obligated to use certain of the net proceeds from this offering to repay $50.0
million (or $55.0 million if the underwriters exercise their option to purchase
additional shares of common stock) of the indebtedness outstanding under the
amended credit agreement and guaranty (the “2024 Credit Agreement”) with Hayfin
Services, LLP (“Hayfin”) and to pay...fees in connection therewith." Please revise to
briefly discuss your relationship to Hayfin, including the percentage of your beneficial
ownership held by entities affiliated with Hayfin.
10.Please revise your disclosure to describe the lock-up agreements discussed on pages
63 and 179 of your registration statement.
Summary consolidated financial data, page 15
11.Please expand your statement of operations and balance sheet pro forma presentations
to include an adjustment for the stock-based compensation expense for the restricted
stock unit that will be granted concurrently with the offering as disclosed on page 13,
along with disclosures that disclose the material terms of the grant, the total amount of
compensation expense to be recognized, the period over which the expense will be
recognized, and the assumptions used to estimate the compensation expense. Refer to
Article 11-02(a)(8) of Regulation S-X for guidance. Please address this comment for
all of your pro forma presentations.
12.Please expand your statement of operations pro forma presentation to include an
adjustment for the interest expense and change in fair value of derivative liability, if
any, associated with the $50 million repayment for the 2024 Credit Agreement. Please
address this comment for all of your pro forma presentations.
Risk Factors
To date we have derived a significant amount of our revenue from a small number of
customers, and face risks associated with a more..., page 21
We note your disclosure that "although [y]our Heartflow Platform had an installed
base of over 1,100 accounts in the United States as of December 31, 2024, the
decision-making function for many of these accounts is concentrated in a relatively
small number of customers, such that the loss of one customer could result in a
disproportionate loss across [y]our accounts." We also note your disclosure on page
82 that "[n]o single customer accounted for 10% or more of [y]our revenue during the
year ended December 31, 2023." Please revise, here and on page 82, to reconcile these 13.

March 5, 2025
Page 5
two statements, including whether a "disproportionate loss" across accounts would
result in a similar loss to your revenue, and note whether any customer accounted for
more than 10% of your revenue during the year ended December 31, 2024. Please
also revise your disclosures on page 82 to clarify the difference, if any, between your
installed base of accounts and customers.
Our Heartflow Platform and the data and models it generates could have bugs, defects or
errors, including human quality control errors..., page 25
14.We note your disclosure that "[you] have in the past, and may in the future,
experience defects or errors in [y]our Heartflow Platform or the data and models it
generates that remain undetected by [y]our analyst-based review process." Please
revise to briefly discuss, if material, these prior defects or errors in the Heartflow
Platform or the data and models it generates, including any related negative impacts
on your business or operations. We also note your disclosure on page 39 that
"[yo]ur products have been in the past, and may in the future, be the subject of
medical device reports of adverse events with the FDA’s Manufacturer and User
Facility Device Experience database, including reports of false negative results and
incorrect or imprecise results or readings." Please revise to briefly discuss these past
medical device reports of adverse events, if material, including any reports of false
negative results and incorrect or imprecise results or readings, and the related impact
on your business or operations.
Off-label or other unlawful promotion of our products could result in costly investigations
and sanctions from the FDA and other..., page 39
15.We note your disclosure here and throughout the filing that the Heartflow Platform
has been "cleared by the FDA, and the equivalent regulatory authorities in Israel,
Saudi Arabia, United Arab Emirates, licensed in Bahrain, CE Marked in the European
Economic Area, the United Kingdom and Australia, received medical device licensing
in Canada and been approved for marketing authorization in Japan by the
Pharmaceuticals and Medical Devices Agency (“PMDA”), all for specific indications
for use." We also note your disclosure on page 125 that "[o]nly the FFRCT Analyses
is authorized for clinical use in the European Economic Area, United Kingdom,
Australia, Canada, and Japan," and that the "Heartflow Platform is regulated in the
United States by the FDA as a Class II medical device." Here and in your prospectus
summary, please revise to note, as you do on page 25, the specific FDA authorization
received by your Heartflow Platform and each of the products within your Heartflow
Platform. Please also revise your disclosure on page 39 to clarify that only the
FFRCT, and not your Heartflow Platform, is authorized for clinical use in the EEA,
the UK, Australia, Canada, and Japan. Please also briefly discuss, or cross-reference
to your disclosures elsewhere, the significance of CE Mark, PMDA, and medical
device licensing approval outside of the United States. Finally, we note your
disclosure on page 36 that you "currently have ongoing responsibilities under U.S.,
U.K., European Economic Area, Switzerland, Canada, Australia, Japan, Saudi Arabia,
United Arab Emirates, Bahrain and Israel (registered or licensed regions) regulations."
Please revise to clarify the nature of the ongoing responsibilities, including whether
each of your products is authorized for clinical use in each of these listed jurisdictions.

March 5, 2025
Page 6
Market and Industry Data, page 70
16.We note your disclosure that "[t]his prospectus contains estimates, projections, and
other information concerning our industry and our business, as well as data regarding
market research, estimates, and forecasts prepared by our management or third parties,
including but not limited to, Clarivate." Please revise your disclosure throughout to
cite to specific sources prepared by third parties, where appropriate. In addition,
please tell us whether you commissioned any industry or market data that you
reference in the prospectus, including from Clarivate. If so, file consents of the
relevant third parties pursuant to Rule 436 of the Securities Act as exhibits to your
registration statement.
Use of Proceeds, page 71
17.We note your disclosure that "[you] expect to use the remainder of the net proceeds
from this offering, together with [y]our existing cash and cash equivalents, to fund
[y]our sales and marketing efforts, fund research and product development activities
and for other general corporate purposes, including working capital, operating
expenses, and capital expenditures." Please revise to briefly discuss these planned
research and product development activities, including the specific product(s) for
which you intend to use these proceeds. Refer to Item 504 of Regulation S-K.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Components of our results of operations, page 82