May 28, 2009 -- After a stroke, you've got very little time to get treatment. But some patients now have a bit more time.
A stroke occurs when a clot cuts off blood flow to parts of the brain. Those parts of the brain soon start to die. A drug called tissue plasminogen activator -- tPA -- dissolves clots and restores blood flow.
But in the real world, it takes time to get a patient to a hospital. How long does a patient have before the benefits of tPA treatment outweigh its very real risk of causing uncontrollable bleeding in the brain?
When tPA was first discovered, it was thought that there might be a six-hour window. But U.S. clinical trials suggested that window was only half as wide -- and current recommendations discourage tPA use more than three hours after onset of a stroke.
Last year, European clinical trials found that selected patients still benefit from tPA up to 4 1/2 hours after a stroke.
Now, an advisory from the American Heart Association formally spells out which patients might benefit from later tPA treatment. But the chairman of the committee that issued the advisory -- Gregory J. del Zoppo, MD, professor of medicine and adjunct professor of neurology at University of Washington, Seattle -- warns patients not to misinterpret the statement.
"The message is that stroke patients still need to come in for treatment as soon as possible. There is no benefit in waiting," del Zoppo tells WebMD. "Despite the fact that patients who come in even 3 to 4 1/2 hours after stroke can benefit, they should not wait."
There are some patients for whom the smaller benefit of late tPA treatment cannot outweigh the very real risk of hemorrhage.
Patients who cannot receive tPA more than three hours after a stroke:
- Patients over age 80
- Patients taking blood thinning drugs (anticoagulants)
- Patients with a history of stroke and diabetes
Del Zoppo says researchers still have not learned why strokes progress more slowly in some patients than in others. It would be a major advance, he says, if doctors could identify late-arriving stroke patients who might still benefit from tPA treatment.
Until then, he says, "If you really want the best results , you'd better come in straight away after a stroke."
The new AHA advisory appears in the August issue of the AHA journal Stroke.