More than 600,000 Americans suffer a stroke each year. Stroke is the third leading cause of death in the US and the leading cause of long-term disability. People who have had a stroke often endure months of rehabilitation to try and recover their pre stroke way of life and independence. The key to a successful recovery, however, often depends on the first few hours following a stroke.

Previous research has shown that if rt-PA, a clot-busting drug that can restore some blood flow to the brain during a stroke, is given within three hours of the onset of symptoms the chances of recovery are improved. But three hours is not a long time for many patients to realize what is happening, get to the hospital, and begin treatment with rt-PA. Whether there is a benefit beyond three hours has not been clearly established.

A new study in the March 4, 2004 issue of The Lancet , indicates that the sooner after a stroke rt-PA is administered, the greater the benefit, especially if administered within 90 minutes. But the researchers also found that rt-PA may still be beneficial after three hours, however, this potential benefit may come with some risks.

About the Study

The researchers analyzed the data of 2,775 men and women from over 300 hospitals and 18 countries who were part of one of six previously conducted studies on rt-PA and stroke recovery. Participants had been diagnosed with a stroke and then randomly assigned to receive either a placebo (control) or rt-PA.

The researchers measured:

  • Length of time between the onset of stroke symptoms and treatment with rt-PA (0-90, 91-180, 181-270, or 271-360 minutes)
  • Participant outcome three months after the stroke
    • Favorable - the participant showed minimal or no disability
    • Unfavorable - the participant showed signs of disability
  • Risk of hemorrhage (bleeding)
  • Risk of death

The researchers examined the relationship between the delay in rt-PA treatment and the participant’s recovery three months after the stroke. They also compared the risk of death and hemorrhaging for participants who received rt-PA versus placebo.

The Findings

The researchers found that the shorter the time between stroke onset and treatment with rt-PA, the greater the likelihood of a favorable three-month outcome. The most benefit was seen when rt-PA was administered within 90 minutes of stroke onset; these participants were nearly three times more likely to have a favorable outcome than those who received the placebo.

There was still a chance of a benefit at 360 minutes, suggesting that there may even be a benefit after this point. However, when the rt-PA was given after 271 minutes there was also an increased risk of death. The researchers also found that 5.9% of the participants who received rt-PA had hemorrhages, compared to only 1.1% of the controls. In the rt-PA treated group, the risk of hemorrhaging seemed to increase with age.

The researchers also noted that the patients with more severe strokes arrived earlier in the ER than those with less severe strokes. Interestingly, rt-PA still had the greatest effect on those treated early—regardless of stroke severity.

One limitation of this study is that the dose of rt-PA differed among the six studies that were analyzed. It should also be noted that the pharmaceutical company Genentech provided the rt-PA and the placebo drug to some of the trials, several of the researchers received funding from corporate sponsors, and two of the researchers are employees of the pharmaceutical company Boehringer Ingelheim. Genentech and Boehringer Ingelheim are manufacturers of rt-PA.

How Does This Affect You?

These results reaffirm previous findings that show the likelihood of benefiting from rt-PA decreases as time goes by during the first three hours after a stroke. This study also suggests that rt-PA may still be effective when given beyond three hours. However, because the chances of recovery are only slightly improved when rt-PA is given between three and six hours, the likelihood that there is a benefit when rt-PA is given beyond this point is small.

Although this study suggests that the window of opportunity for stroke treatment is longer than previously thought, this does not mean that you should delay seeking treatment if you have a stroke. Early treatment clearly reduces your risk of disability if you’re treated with rt-PA.

Like with heart attacks , the sooner treatment is sought, the better your chance of recovery.

Since time is of the essence, it’s important to be aware of the symptoms of a stroke and to call 911 immediately. Stroke symptoms usually occur suddenly and include:

  • Weakness or numbness of the face, arm, or leg on one side of the body
  • Blurry, dimming, or no vision
  • Difficulty swallowing, talking, or comprehending others
  • Dizziness, falling, or loss of balance
  • Severe or unusual headache