FRIDAY, May 7, 2004 (HealthDayNews) -- Surgery to clean out deposits that narrow the main artery to the brain can halve the risk of stroke for people who have no telltale symptoms of impending trouble, a British study finds.
Only 6 percent of people with significant blockage but no symptoms who had the procedure, called carotid endarterectomy, suffered strokes over the next five years, compared to 12 percent of those with the same condition who did not have surgery, said a report in the May 8 issue of The Lancet.
"We think the balance of risk is strongly in favor of surgery," said Dr. Alison Halliday, a consultant vascular surgeon at St. George's Medical School in London, who led the Asymptomatic Carotid Surgery Trial.
The new results settle a controversy that arose from a similar but smaller American trial done from 1987 to 1993, said Dr. James Toole, a professor of neurology at Wake Forest Baptist Medical Center who led that trial.
Both trials produced essentially similar results, but the British study had nearly twice the number of participants, 3,120 compared to 1,662.
"The data we had were very suggestive, but skeptics said a larger study of longer duration was needed," Toole said.
"We actually began our study before his study was reported," Halliday said. "After that report, we sat down and discussed the results. We decided that there was not sufficient evidence to know whether the operation would be of value from a European perspective, so we decided to recruit a larger number of patients."
There was one major difference in the two trials. Toole's group found a benefit for men but not women, while Halliday's trial found similar benefits for both sexes. One explanation is that the British trial included a large enough group of women to show a benefit, Halliday said.
"Their data and our data were hand in glove all the way down the line with that one difference," Toole said.
There is general agreement that carotid endarterectomy is needed for patients who have evident problems, such as a previous minor stroke, he said. The issue has been whether surgery will help patients whose carotid narrowing is discovered before symptoms develop.
That issue now appears to have been settled, Toole said. The two studies show that carotid endarterectomy should be considered for any patient whose artery has been narrowed by 60 percent or more, he said.
But the procedure need not be done at once, Toole said, because there are other ways to improve blood flow through the carotid artery.
A symptom-free person with 60 percent or more blockage should be told to take aspirin and a cholesterol-lowering drug, to reduce blood pressure, and to stop smoking, among other lifestyle changes, Toole said.
"I would give it six months and have the test again to see if the blockage has gone away," he said. "The condition can get better. If it does not, surgery should be considered."
But the British results indicate that age might be an issue, Halliday said. The study found no benefit from surgery for people 75 or older. The researchers will follow those participants for another 10 years, to see whether evidence of a benefit emerges, she said.
Questions about carotid endarterectomy are asked and answered by the National Institute of Neurologicl Diseases and Stroke.