Amendment to Current Report (Form 8-K/A)

SeaStar Medical Announces 1-for-10 Reverse Split

DENVER, CO (December 23, 2025) - SeaStar Medical Holding Corporation (Nasdaq: ICU), a commercial-stage healthcare company focused on transforming treatments for critically ill patients facing organ failure and potential loss of life, announced today the Company's 1-for-10 reverse stock split (Reverse Split), which will become effective as of 12:01 a.m. Eastern Time on January 5, 2026. The Company's common stock will begin trading on a post-split adjusted basis on The Nasdaq Capital Market (Nasdaq) effective with the open of the market on January 5, 2026. SeaStar Medical's stock will continue to trade under the ticker symbol "ICU."

Authorization for the Reverse Split was approved by the Company's stockholders at SeaStar Medical's 2025 Special Meeting of Stockholders held on December 18, 2025. The objective of the Reverse Split is to increase the market price for the Company's common stock to, among things, enable the Company to regain compliance with the $1.00 minimum bid price requirement under applicable Nasdaq Listing Rules. The Company's common stock will trade under a new CUSIP number - 81256L302.

As a result of the Reverse Split, each 10 pre-split shares of common stock outstanding will automatically combine and convert to 1 issued and outstanding share of common stock. Stockholders of record who otherwise would be entitled to receive fractional shares will receive one whole share of common stock in lieu of such fractional share. The Reverse Split reduces the number of shares of common stock issuable upon the exercise or vesting of its outstanding stock options and certain warrants in proportion to the ratio of the Reverse Split and causes a proportionate increase in the exercise prices of such stock options and warrants.

Stockholders of record will receive information regarding their share ownership following the reverse stock split from the Company's transfer agent, Continental Stock Transfer and Trust Company. Continental Stock Transfer and Trust Company can be reached at 800-509-8856. Stockholders owning shares via a bank, broker or other nominee will have their positions automatically adjusted to reflect the Reverse Split and will not be required to take further action in connection with the Reverse Split, subject to brokers' particular processes.

For additional information regarding the Reverse Split, please refer to SeaStar Medical's Current Report on Form 8-K filed with the Securities and Exchange Commission on December 18, 2025.

About SeaStar Medical

SeaStar Medical is a commercial-stage healthcare company focused on transforming treatments for critically ill patients facing organ failure and potential loss of life. The QUELIMMUNE (SCD-PED) therapy is SeaStar Medical's first commercial product based on its patented Selective Cytopheretic Device (SCD) technology. The QUELIMMUNE (SCD-PED) therapy was approved in 2024 by the U.S. Food and Drug Administration (FDA). It is the only FDA approved product for the ultra-rare condition of life-threatening acute kidney injury (AKI) due to sepsis or a septic condition in critically ill pediatric patients. SeaStar Medical's Selective Cytopheretic Device (SCD) therapy has been awarded Breakthrough Device Designation for six therapeutic indications by the FDA, enabling the potential for a speedier pathway to approval and preferable reimbursement dynamics at commercial launch. The company is currently conducting the NEUTRALIZE-AKI pivotal trial of its SCD therapy in adult patients with AKI requiring continuous renal replacement therapy (CRRT), a life-threatening condition with no effective treatment options that impacts over 200,000 adults in the U.S. annually.

For more information visit www.seastarmedical.com or visit us on LinkedIn or X.