Sec Form 3 Filing - WELDON WILLIAM C @ Heartflow, Inc. - 2025-08-07

FORM 3 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 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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1. Name and Address of Reporting Person WELDON WILLIAM C 2. Issuer Name and Ticker or Trading Symbol Heartflow, Inc. [ HTFL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O HEARTFLOW, INC., 331 E. EVELYN AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 08/07/2025 (Street) MOUNTAIN VIEW, CA94041 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 56,256 ( 1 ) D

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Stock Option $ 8.33 ( 1 ) ( 2 ) 09/20/2027 Common Stock 17,123 ( 1 ) D Stock Option $ 8.33 ( 1 ) ( 2 ) 04/22/2030 Common Stock 17,123 ( 1 ) D Stock Option $ 8.33 ( 1 ) ( 3 ) 03/24/2032 Common Stock 34,246 ( 1 ) D Stock Option $ 8.33 ( 1 ) ( 4 ) 03/24/2032 Common Stock 17,123 ( 1 ) D Stock Option $ 2.22 ( 1 ) ( 5 ) 07/10/2033 Common Stock 35,638 ( 1 ) D Stock Option $ 2.22 ( 1 ) ( 6 ) 09/26/2033 Common Stock 57,078 ( 1 ) D Series D Preferred Stock ( 7 ) ( 7 ) ( 7 ) Common Stock 83,442 ( 7 ) D Series F Preferred Stock ( 8 ) ( 8 ) ( 8 ) Common Stock 25,160 ( 8 ) D Series F-1 Preferred Stock ( 8 ) ( 8 ) ( 8 ) Common Stock 27,704 ( 8 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other WELDON WILLIAM C C/O HEARTFLOW, INC. 331 E. EVELYN AVENUE MOUNTAIN VIEW, CA94041 X Signatures /s/ Angela Ahmad, Attorney-in-Fact for William C. Weldon 08/07/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The number of shares of common stock and exercise price, as applicable, give effect to the 1-for-2.92 reverse stock split of Heartflow, Inc.'s ("Heartflow") common stock, which became effective on July 31, 2025. ( 2 )These stock options are fully exercisable. ( 3 )The option is vested and exercisable as to 28,520 shares, and the remaining shares will vest and become exercisable in monthly installments until March 25, 2026, subject to continued service through the applicable vesting date. ( 4 )The option will vest 100% on the one-year anniversary of the closing of Heartflow's initial public offering. ( 5 )The option is vested and exercisable as to 13,482 shares, and the remaining shares will vest and become exercisable in monthly installments until July 1, 2027, subject to continued service through the applicable vesting date. ( 6 )The option is vested and exercisable as to 19,973 shares, and the remaining shares will vest and become exercisable in monthly installments until September 26, 2027, subject to continued service through the applicable vesting date. ( 7 )Each share of Series D preferred stock is convertible on a 1-to-0.6467 basis into shares of Heartflow's common stock and has no expiration date. The Series D preferred stock will automatically convert into the underlying shares of common stock upon the closing of Heartflow's initial public offering. The conversion rate gives effect to the 1-for-2.92 reverse stock split of Heartflow's common stock, which became effective on July 31, 2025. ( 8 )Each share of Series F preferred stock and Series F-1 preferred stock is convertible on a 1-to-0.3425 basis into shares of Heartflow's common stock and has no expiration date. The Series F preferred stock and Series F-1 preferred stock will automatically convert into the underlying shares of common stock upon the closing of Heartflow's initial public offering. The conversion rate gives effect to the 1-for-2.92 reverse stock split of Heartflow's common stock, which became effective on July 31, 2025.

Remarks: Exhibit 24 - Power of Attorney.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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