UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING
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SEC File Number:	001-39927
CUSIP Number:	502015100

(Check one):	ý Form 10-K	o Form 20-F	o Form 11-K	o Form 10-Q	o Form 10-D
	o Form N-CEN	o Form N-CSR
	For Period Ended:	December 31, 2023
	o Transition Report on Form 10-K
	o Transition Report on Form 20-F
	o Transition Report on Form 11-K
	o Transition Report on Form 10-Q
	For the Transition Period Ended:

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Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:

PART I — REGISTRANT INFORMATION

SEASTAR MEDICAL HOLDING CORPORATION

Full Name of Registrant

N/A

Former Name if Applicable

3513 Brighton Blvd., Suite 410

Address of Principal Executive Office (Street and Number)

Denver, CO 80216

City, State and Zip Code

PART II — RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate)

	(a)	The reason described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense
x	(b)	The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and

(c) The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

SEC 1344 (06-19) Persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

PART III — NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-CEN, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period.

SeaStar Medical Holding Corporation (the “Company”) has determined that it is unable, without unreasonable effort or expense, to file its Annual Report on Form 10-K for the year ended December 31, 2023 by the prescribed due date primarily because additional time is needed for the Company to complete the work required to restate financial statements of prior periods, as disclosed in more detail in the Current Report on Form 8-K filed on March 27, 2024 (the “Form 8-K”).

The Company expects to file the Form 10-K for the year ended December 31, 2023 within the fifteen-day extension period provided under Rule 12b-25 of the Securities Exchange Act of 1934, as amended.

(Attach extra Sheets if Needed)

PART IV — OTHER INFORMATION

(1)	Name and telephone number of person to contact in regard to this notification
	Eric Schlorff	(844)	427-8100
	(Name)	(Area Code)	(Telephone Number)
(2)	Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed ? If answer is no, identify report(s).
			ý Yes o No
(3)	Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?
			ý Yes o No
	If so: attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made. As disclosed in more detail inThe proposed restatement described above impacts non-cash items in the Company’s financial statements. the Form 8-K, a restatement of the Company’s audited financial statements for the fiscal year ended December 31, 2022 and unaudited interim financial statements for the fiscal quarters ended March 31, 2023, June 30, 2023 and September 30, 2023 would be appropriate in order to restate accounting treatment of certain financial instruments. The proposed restatement described in the Form 8-K impacts non-cash items in the Company’s financial statements.

SEASTAR MEDICAL HOLDING CORPORATION

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned hereunto duly authorized.

Date	April 1, 2024	By	/s/ Eric Schlorff
			Eric Schlorff
			Chief Executive Officer

INSTRUCTION: The form may be signed by an executive officer of the registrant or by any other duly authorized representative. The name and title of the person signing the form shall be typed or printed beneath the signature. If the statement is signed on behalf of the

registrant by an authorized representative (other than an executive officer), evidence of the representative’s authority to sign on behalf of the registrant shall be filed with the form.

	ATTENTION
Intentional misstatements or omissions of fact constitute Federal Criminal Violations (See 18 U.S.C. 1001).