A Chinese multicenter randomized clinical trial demonstrated that intravenous alteplase administration up to 24 hours post–stroke onset significantly improved functional outcomes in patients who experienced acute ischemic stroke. The preliminary findings, presented at the American Stroke Association's International Stroke Conference 2025, challenge current therapeutic time windows for thrombolytic therapy.

In the trial of 372 patients across 26 stroke centers, 40% of alteplase-treated patients achieved minimal or no disability at 90 days compared to 26% in the standard-care group—representing a 54% increased likelihood of functional recovery.

"We believe these findings mean more people may return to normal or near-normal lives after a stroke, even if they receive treatment later than originally thought beneficial," said principal investigator Min Lou, MD, PhD, Professor at the Second Affiliated Hospital of Zhejiang University's School of Medicine, in a press release.

The trial enrolled patients presenting 4.5 to 24 hours after symptom onset. The mean age of participants was 72 years; 43% were female. Eligibility required computed tomography (CT) perfusion imaging evidence of salvageable brain tissue. The control group received standard antiplatelet therapy according to the Chinese Guidelines for Diagnosis and Treatment of Acute Ischemic Stroke 2018. The primary outcome measure was a score of 0 or 1 on the modified Rankin scale at 90 days.

Further analysis of the trial outcomes revealed identical mortality rates of 10.8% between groups, with symptomatic intracranial hemorrhage occurring in 3.8% of alteplase-treated patients compared to 0.5% in controls. Less than 3% of participants in either group required rescue mechanical thrombectomy.

The findings contrast with existing guidelines. The American Heart Association/American Stroke Association's 2019 Guidelines for Early Management of Acute Ischemic Stroke maintain that intravenous alteplase administration within 4.5 hours remains the standard of care. In China, the approved window is 4.5 hours, while U.S. Food and Drug Administration approval limits administration to within 3 hours of symptom onset, with selected patients eligible for up to 4.5 hours.

The investigators acknowledged potential bias due to the open-label design and question generalizability beyond Chinese populations. The preliminary results await peer review and full manuscript publication.

"This method of treatment could become the new standard, especially in hospitals that use CT perfusion imaging," Dr. Lou stated. "This could extend treatment eligibility to millions more patients across the globe."