SeaStar Medical Holding Corp

This proxy statement (the “Proxy Statement“) is furnished in connection with the solicitation by the Board of Directors of SeaStar Medical Holding Corporation (the "Company") of proxies to be voted at our Annual Meeting of Stockholders to be held on June 4, 2024 (the “Annual Meeting”), at 10:00 a.m. Mountain Time, and at any continuation, postponement, or adjournment of the Annual Meeting. The Annual Meeting will be held virtually via live webcast. You will be able to attend the Annual Meeting online by visitingwww.proxydocs.com/ICU and entering your 12-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. You will be able to vote your shares electronically and submit your written questions prior to and during the meeting through the online website.

Holders of record of our Common Stock, par value $0.0001 per share (the “Common Stock“), as of the close of business on April 26, 2024 (the “Record Date”), will be entitled to notice of and to vote at the Annual Meeting and at any continuation, postponement, or adjournment of the Annual Meeting. As of the Record Date, there were approximately 75,419,458 shares of Common Stock outstanding and entitled to vote at the Annual Meeting. Each share of Common Stock is entitled to one vote on any matter presented to stockholders at the Annual Meeting.

The Company will begin mailing, or otherwise make available to stockholders, this Proxy Statement, Notice of Annual Meeting of Stockholders, and proxy card (the “Proxy Materials”) containing instructions on how to access the Proxy Materials and how to vote and the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the “2023 Annual Report”) to stockholders on or about May 6, 2024. In this Proxy Statement, “Company”, “we”, “us”, and “our” refer to SeaStar Medical Holding Corporation.

When and where will the Annual Meeting be held?

The Annual Meeting will be held on Tuesday, June 4, 2024 at 10:00 a.m., Mountain Time. The Annual Meeting will be a completely virtual meeting, which will be conducted via live webcast. You will be able to attend the Annual Meeting online and submit your questions during the meeting by visiting www.proxydocs.com/ICU and entering your 12-digit control number included in your Notice of Internet Availability of Proxy Materials, on your proxy card or on the instructions that accompanied your Proxy Materials. If you lose your 12-digit control number, you may join the Annual Meeting as a “Guest” but you will not be able to vote.

Availability of Proxy Materials

The Proxy Materials are being mailed on or about May 6, 2024 to all stockholders entitled to notice of, and to vote at, the Annual Meeting. SeaStar Medical Holding Corporation’s 2023 Annual Report, which includes its Form 10-K for the year ended December 31, 2023, will accompany the Proxy Materials.

Proposals

At the Annual Meeting, our stockholders will be asked:

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to elect three Class II Directors to serve until the 2027 annual meeting of stockholders, or until their successors shall have been duly elected and qualified (“Proposal 1”);

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to approve an amendment and restatement of the Company’s 2022 Omnibus Equity Incentive Plan (the “Plan”) to increase the number of authorized shares of Common Stock from 3,278,457 to 9,778,457 (“Proposal 2”);

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to approve, for purposes of complying with Nasdaq Listing Rule 5635(d), the issuance of 20% or more of outstanding shares of Common Stock upon exercise of Series A warrants to purchase 10,840,761 shares of

Common Stock and Series B warrants to purchase 5,420,381 shares of Common Stock pursuant to the terms of the Securities Purchase Agreement (as defined below) (“Proposal 3” or the “Nasdaq Proposal”); and

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To ratify the appointment of WithumSmith+Brown, PC as our independent registered public accounting firm for the fiscal year ending December 31, 2024 (“Proposal 4”).

We know of no other business that will be presented at the Annual Meeting. If any other matter properly comes before the stockholders for a vote at the Annual Meeting, however, the proxy holders named on the Company’s proxy card will vote your shares in accordance with their best judgment.

Recommendations of the Board

The Board of Directors (the “Board”) recommends that you vote your shares as indicated below. If you return a properly completed proxy card, or vote your shares by telephone or Internet, your shares of common stock will be voted on your behalf as you direct. If not otherwise specified, the shares of Common Stock represented by the proxies will be voted, and the Board recommends that you vote:

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FOR the election of Allan Collins, MD as Class II Director;

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FOR the election of Jennifer A. Baird as Class II Director;

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FOR the election of Bernadette N. Vincent as Class II Director;

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FOR the approval of an amendment and restatement of the Company’s 2022 Omnibus Equity Incentive Plan to increase the number of authorized shares of Common Stock from 3,278,457 to 9,778,457;

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FOR the approval, for purposes of complying with Nasdaq Listing Rule 5635(d), of the full issuance of the Transaction Shares; and

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FOR the ratification of the appointment of WithumSmith+Brown, PC as our independent registered public accounting firm for the fiscal year ending December 31, 2024.

If any other matter properly comes before the stockholders for a vote at the Annual Meeting, the proxy holders named on the Company’s proxy card will vote your shares in accordance with their best judgment.

Information About This Proxy Statement

Why you received this Proxy Statement. You are viewing or have received these Proxy Materials because our Board is soliciting your proxy to vote your shares at the Annual Meeting. This Proxy Statement includes information that we are required to provide to you under the rules of the Securities and Exchange Commission (“SEC”) and that is designed to assist you in voting your shares.

Printed Copies of Our Proxy Materials. You have received or will receive printed copies of our Proxy Materials, and instructions regarding how you can vote are contained on the proxy card included in the materials.

Householding. The SEC’s rules permit us to deliver a single set of Proxy Materials to one address shared by two or more of our stockholders. This delivery method is referred to as “householding” and can result in significant cost savings. To take advantage of this opportunity, we have delivered only one set of Proxy Materials to multiple stockholders who share an address, unless we received contrary instructions from the impacted stockholders prior to the mailing date. We agree to deliver promptly, upon written or oral request, a separate copy of the Proxy Materials, as requested, to any stockholder at the shared address to which a single copy of those documents was delivered. If you prefer to receive separate copies of the Proxy Materials, contact Continental Stock Transfer and Trust Company at 1-800-509-8856 or in writing at Continental Stock Transfer and Trust, 1 State Street 30 th Floor, New York, NY 10004-1561.