Aspirin Taken Right After a Stroke May Prevent a Second One

From the WebMD Archives

June 1, 2000 -- Chalk another one up for aspirin: Researchers have concluded that giving aspirin to stroke victims as soon as they arrive at the hospital reduces their risk of having a second stroke.

In the first few days after having a stroke, patients are at high risk of having another one, says Richard Peto, a professor at Oxford University and co-author of an analysis published in the journal Stroke. "We found that aspirin didn't do very much for repairing the damage done already by the initial stroke, but ... it reduced the likelihood of having another stroke in the hospital," he tells WebMD.

What's more, he says, it appears to be beneficial to give aspirin to stroke victims right away even if doctors aren't 100% sure which type of stroke the patient has had.

There are two kinds of strokes: ischemic stroke, caused by a clot that blocks a blood vessel supplying the brain with blood, and hemorrhagic or bleeding stroke, caused by a leaky blood vessel that bleeds into the brain. A CT scan of the head can help a doctor determine if a stroke is the ischemic or hemorrhagic type.

Aspirin, which thins the blood and thereby prevents clots, is currently used to reduce the long-term risks of a second stroke in patients who've had an ischemic stroke. But giving aspirin to patients who've had a hemorrhagic stroke is considered dangerous, as it can cause more bleeding and more damage.

"Basically, doctors on the whole tend to wait for things to settle down; they wait until they're sure of the diagnosis -- whether it is ischemic or hemorrhagic," Peto says. "If you start aspirin a bit earlier -- the first week or two is the time of highest risk -- it's the time actually when aspirin is most protective. And what we have shown is that you can safely start aspirin early on."

Peto and colleagues analyzed the results of two very large studies, involving a total of 40,000 stroke patients, and found that compared to patients who didn't get aspirin, a third fewer of the patients who received aspirin had a recurrent stroke. Put another way, giving aspirin to 1,000 people prevented about nine deaths or recurrent strokes.

Study author Zheng Ming Chen, MD, DPhil, of Oxford University, says in a press release that preventing nine strokes or deaths out of 1,000 patients may not sound like much: "But if you consider there are several million strokes worldwide each year, by treating one million of those with one year of aspirin therapy, this will prevent about 20,000 strokes or deaths."

Even hemorrhagic stroke patients who were inadvertently given aspirin did reasonably well, says Peto. "There were about 800 patients who, in retrospect, had probably been misdiagnosed and they weren't any worse off than patients who hadn't received aspirin.

"I think aspirin should become routine for suspected stroke in the way that it is for suspected heart attack," he says. "What we have shown is that ... the sooner you go ahead and act, the better, in terms of avoiding recurrence."

Vital Information:

  • There are two types of stroke: an ischemic stroke occurs when a blood clot blocks a vessel in the brain, and a bleeding stroke occurs when the vessel leaks blood.
  • People who suffer a stroke are at high risk of having a second stroke within a few days, but taking aspirin can lower that risk.
  • Physicians have been wary of giving early aspirin therapy to stroke patients, in case the type of stroke was misdiagnosed or the ischemic stroke turned into a bleeding stroke, but this research shows that the aspirin therapy is relatively safe.