However, the new method of delivering the drugs also increases the chances of bleeding on the brain.
A review of 27 studies has found that delivering thrombolytic therapy directly into the affected artery reduces disability and death caused by stroke. However, the chance of bleeding on the brain increases, says Dr. Mark J. Alberts, director of the stroke program at Northwestern University. He is one of the authors of the study, which appears in the current issue of Stroke.
"You get more benefit" from delivering the drugs directly into the artery than from the more standard method of delivering thrombolytics intravenously, or from not being treated with thrombolytics at all, "but at a higher risk," he says.
An ischemic stroke is caused by a blood clot that blocks a blood vessel or artery in the brain; about 80 percent of all strokes are ischemic. The second kind of stroke, known as a hemorrhagic stroke, is caused by a blood vessel in the brain that breaks and bleeds into the brain, according to the National Institute of Neurological Disorders and Stroke.
Thrombolytics -- or "clot-busters," as the drugs are often called -- that are given intravenously must be administered within three hours of a stroke to be most effective.
When they're given directly into an artery, they can be administered within six hours, adding a crucial three hours into the equation, Alberts says. Because the drugs go directly to the clot, they tend to work most effectively. And they don't spread throughout the body, risking general bleeding.
In their review, the researchers found that 18 percent more stroke victims who received thrombolytics in the artery had no residual disability or only minor disability after their stroke, compared to stroke victims who did not receive any thrombolytics.
Thirteen percent fewer stroke patients who received intra-arterial clot-busting therapy died as a result of stroke, compared to those who didn't receive thrombolytics, according to the new study.
However, risk of suffering "symptomatic intracranial hemorrhage" was about 6.5 percent higher, Alberts says.
Stroke and subsequent disability is a major health problem in the United States, with about 600,000 ischemic strokes diagnosed each year, says Dr. Dawn Bravata, an assistant professor of medicine at Yale University.
Thrombolytic therapy would not benefit victims of hemorrhagic stroke, Alberts says.
While the new method of giving the drug directly into an artery lets patients be treated within a six-hour time frame, it also requires the victim first have an angiogram, an X-ray of the blood vessels, to determine there is a clot.
"It's a bit of a double-edged sword," Alberts admits, since the angiogram increases the time before the patient can be treated.
Bravata says Alberts' study "provides more evidence that intra-arterial therapy is beneficial." However, while the therapy may be good, hospitals must have angiography equipment and people skilled to insert the drug directly into the artery. This may make the therapy's use less widespread than one would otherwise expect, she says.
Alberts says randomized, prospective trials need to be conducted on this method of delivering thrombolytics. However, for people who cannot get intravenous thrombolytics within the three hours following a stroke, "this can be given within six hours and may be a reasonable option on a case-by-case basis," he says.
What To Do
To learn more about thrombolytics, check with the University of California, Davis Medical Center. For more information on stroke, visit the National Institute of Neurological Disorders and Stroke.