The Window of Opportunity for Effective Stroke Treatment Has Been Widened

A new study suggests that the traditional three-hour time window for stroke treatment is too short, and that treatment can benefit stroke patients up to 4.5 hours after they experience their first symptom.

Researchers at Stanford University Stroke Center (Palo Alto, CA, USA), University Hospitals of Leuven (Belgium), and Boehringer Ingelheim Pharma (Ingelheim, Germany) conducted a meta-analysis, combining data from four major clinical trials that involved a total of 1,622 patients who arrived at the hospital between three and 4.5 hours after their symptoms started. The effect of tissue plasminogen activator (tPA) on favorable outcome and mortality was assessed. The results of the meta-analysis showed that tPA treatment improved the odds of a favorable outcome by 31%, with no significant difference in mortality compared to placebo treated patients. The study was published online on May 28, 2009, in the journal Stroke.

"Doctors from all over the world have tried to increase the treatment time window,” said lead author Maarten Lansberg, M.D., Ph.D., an assistant professor of neurology and neurological sciences at Stanford. "But evidence from individual clinical trials has been confusing: Some studies demonstrated a benefit from treatment after three hours, while others were inconclusive or reported no benefit.”

TPA is a serine protease found naturally on endothelial cells. As an enzyme, it catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown. Because it works on the clotting system, tPA is used in clinical medicine to treat stroke; however, the timing of treatment is important, since administering tPA during a stroke can also cause bleeding inside the brain. Current guidelines dictate that tPA must be given within 3 hours of the onset of symptoms, since the longer a patient waits to get treatment, the more likely it is that the risks of treatment will outweigh the benefits. Because of this, only about 3% of stroke patients currently qualify for treatment.

Related Links:
Stanford University Stroke Center
University Hospitals of Leuven
Boehringer Ingelheim Pharma