Nearly 800,000 people have strokes every year in America.
The best treatment, TPA, has to be given within three hours, and doctors estimate only five percent of patients can make that window.
In Healthy Living, we learn that a new treatment is now in clinical trial and could give patients precious additional time.
Dr. Clark says the treatment has no negative side effects but might not be appropriate for cancer patients, because it could make cancer cells grow faster.
A phase three trial involving about 300 patients across the country could begin in a few months at locations to be announced.