(Ivanhoe Newswire) -- Stroke victims have a longer window to get life-saving treatment than originally thought, according to researchers. A new study suggests the traditional three-hour time window for doctors to administer a potent clot-busting medication to save brain tissue is too short. Researchers showed that treatment could benefit patients up to four and a half hours after they experience their first stroke symptom.

Every year, more than 750,000 Americans suffer a stroke, or brain attack, due to a sudden drop in blood flow to the brain. Most strokes are ischemic, meaning a blocked artery causes them. For these strokes, a medication called tissue plasminogen activator, or tPA, can open blocked blood vessels and restore blood flow to the brain.

"We've known that this treatment works for ischemic stroke since 1955," Maarten Lansberg, MD, PhD, assistant professor of neurology and neurological sciences at Stanford was quoted as saying. "But in the United States, only about 3 percent of stroke patients end up getting treated. Most of them are ineligible because they come to the hospital after the three-hour time window."

In the study, researchers looked at 1,622 patients who arrived at the hospital between three and four and a half hours after their symptoms started. Treatment with tPA improved odds of a favorable outcome by 31 percent. Researchers also found no change in the death rate among patients treated with tPA during the three to four and a half hour window.

"A favorable outcome means that patients are either completely back to normal or they have minimal symptoms, like some numbness or a slight facial droop," Lansberg was quoted as saying. "But they can do everything in their normal life that they were able to do before the stroke happened"

Source: Stroke, May 28, 2009