7 May 1999
Good results for balloon procedure in the brain
The relatively routine procedure that uses balloons to unblock clogged arteries in the heart to prevent heart attacks shows promise for doing the same job in the brain. And if narrowed blood vessels in the brain can be opened, stroke may be prevented, researchers reported recently in Stroke: Journal of the American Heart Association.
The angioplasty balloon procedure opened blocked arteries in 91 percent of the study participants, says lead researcher Michael P. Marks, M.D., of the Stanford Stroke Center. The 23 individuals in the study were between the ages of 31 to 84 and were treated at the Stanford University Medical Center. Ten of the patients had prior strokes and the other patients had severe blockages in the brain arteries.
"Our study, which is the first to follow patients for up to three years, also seems to indicate that angioplasty reduces risk of stroke. However, larger studies are needed to confirm that finding," says Marks, associate professor of radiology and director of neuroradiology at the Stanford Stroke Center.
Balloon angioplasty may prove as effective in preventing stroke as it has in preventing heart attacks because the procedure treats the same disease process. Both strokes and heart attacks are caused by the fatty-plaque obstructions, called atherosclerosis, that impair blood flow in arteries and blood vessels of the heart and brain. A total of 660,000 angioplasty procedures are conducted in the United States to reduce the risk of heart attack in people whose heart arteries are obstructed by atherosclerosis.
Because angioplasty to prevent stroke is an experimental procedure, relatively few people are receiving this therapy. Previous studies have included a small series of patients who were followed for a limited period of time.
"Although this procedure can be performed for stroke with a high degree of technical success, there is still a risk associated with the procedure," Marks says. "It should be reserved for individuals who do not respond to drug therapy alone."
In addition to angioplasty, coronary bypass surgery is another common treatment for restoring blood flow to the heart. However, bypass surgery is impractical for treating narrowed vessels that feed blood to the brain.
In angioplasty, a tiny balloon-tipped catheter is threaded through a blood vessel. When the catheter reaches the area of blockage, the balloon is inflated, compressing atherosclerotic plaque, or fatty build-up, against the vessel lining and opening a wider channel for blood flow.
Although angioplasty has a high technical success rate, it still carries risks. In the stroke study, one patient died of a ruptured blood vessel at the time of the procedure, and another patient had a blood clot near the site of the original blockage an hour after undergoing the procedure. That clot was successfully dissolved with medication.
During about three years of follow-up, two individuals in the study who were treated with angioplasty had strokes in the area of the blockage and three had strokes in other areas of the brain. All patients received continued medical therapy after the procedure. After three years, the patients had an annual stroke rate of 3.2 percent in the area of the blockage and an overall annual stroke rate of 4.8 percent.
"It is difficult to know precisely how these stroke rates would compare to rates of stroke among individuals treated with medication (such as warfarin and aspirin) alone," Marks says. Some limited data available from other studies indicates an annual stroke rate of 7.8 percent to 10.7 percent when individuals are treated with medication alone. "Based on these data, it appears that angioplasty has significantly reduced the stroke rate.
"This study indicates a need for additional studies comparing the usefulness of angioplasty versus medication alone," Marks says. "At this point there is no other proven therapy to treat this problem, especially for patients who are having continuing problems."