A new study presented at the American Stroke Association’s International Stroke Conference 2025 brings hope to stroke patients around the world.
Researchers found that the clot-busting drug alteplase can still improve recovery when given up to 24 hours after the start of an ischemic stroke — far beyond the usual treatment window.
The study was led by Dr. Min Lou, a professor at the Second Affiliated Hospital of Zhejiang University’s School of Medicine in China. The research shows that patients treated with alteplase had a 54% higher chance of recovery compared to those who received standard care, even when treatment started many hours after symptoms began.
In the U.S., alteplase is typically approved for use within three hours of stroke onset and may be used up to 4.5 hours for certain patients. In China, the treatment window is also limited to 4.5 hours. However, this new study pushes the boundaries of what may be possible for stroke treatment, especially for patients who cannot get to a hospital quickly.
The study enrolled 372 patients who had experienced a stroke between 4.5 and 24 hours before arriving at a hospital.
All patients underwent CT perfusion imaging, a type of brain scan that helps doctors identify which areas of the brain might still be saved by treatment. Half of the participants received alteplase, while the other half received standard care with antiplatelet medication.
The results were encouraging. After 90 days, 40% of patients who received alteplase had little to no disability, compared to 26% of those who received standard care. This represents a significant improvement in functional recovery. Death rates were the same in both groups — around 10.8%.
However, there was a slightly higher risk of brain bleeding in the alteplase group (3.8% vs. 0.5%). Researchers believe this is a manageable risk, especially considering the potential benefits.
“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 possible,” said Dr. Lou. “This method could become the new standard, especially in hospitals that have access to CT perfusion imaging.”
Another promising aspect is that less than 3% of patients in either group needed rescue treatment to remove the clot manually, showing that alteplase alone can be effective even after a longer delay.
Dr. Lou also emphasized the need to study other clot-dissolving medications, such as tenecteplase, to see if they are also safe and effective when given after the usual treatment window. He pointed out that more research is needed to confirm if these findings apply to other populations and healthcare systems outside of China.
The study was a multicenter, randomized trial conducted at 26 stroke centers across China. The average patient age was 72, and 43% were women. The main goal was to measure how many patients scored 0 or 1 on the modified Rankin scale — a scale from 0 (no symptoms) to 6 (death) — at 90 days after treatment.
While the study has some limitations — such as participants and researchers knowing which treatment was being used — the use of widely available CT imaging software makes the results relevant to real-world hospital settings.
These findings could lead to a major shift in how and when stroke patients are treated, potentially saving brain function for many people who previously would have been considered too late for treatment.
If you care about stroke, please read research about Thanks to his wife’s quick reaction, postal worker fully recovered from a stroke and findings of new hope for people with irregular heartbeat to prevent stroke.
For more information about stroke, please read research about Stronger high blood pressure treatment may help prevent stroke in older people and findings of Stroke death risk increases again after falling for 40 years.
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