A surgical procedure to widen carotid arteries that have become narrowed and restrict blood flow to the brain reduces the risk of stroke over a 10-year period.
According to British researchers the carotid artery supplies blood carrying oxygen to the head, so a procedure to widen it helps restore blood flow to the brain. However, the operation, called a carotid endarterectomy, has about a 3 percent risk of causing an immediate stroke, the researchers cautioned.
For some elderly patients, this risk may outweigh any long-term benefit. But older, healthy patients will likely benefit from the procedure, the study authors noted.
Recent studies suggest that the rate of stroke in patients with [narrowed carotid arteries without symptoms] is lower than the rates found in this trial, according to the highlighted report posted by the American Association for Critical Illness Insurance, the trade group.
Although the study found the rate of stroke in patients without a carotid endarterectomy to be 1.8 percent a year over a 10-year period, the rates are thought to be about 1 percent a year, but may be as low as around 0.5 percent a year.
The lower rates of stroke, medical reserachers report, are thought to be due to advances in medical treatment such as blood pressure control, antiplatelet drugs and more widespread use of statins.
The report is published in the Sept. 25 issue of The Lancet.
In the Asymptomatic Carotid Surgery Trial, a research team led by Dr. Alison Halliday of the John Radcliffe Hospital, the University of Oxford, randomly assigned 3,120 patients with narrowed carotid arteries to surgery or to no surgery until their condition required it.
Some of the patients originally assigned to the “no surgery” group did undergo the operation during the study, the researchers noted.
A total of 1,979 operations were performed. Among these the risk of stroke within 30 days was 3 percent, including 26 minor and 34 disabling or fatal strokes, Halliday’s team reported.
Over an average of five years of follow-up, 4.1 percent of those who underwent the procedure suffered a stroke, compared with 10 percent of those who did not have the operation.
At 10 years, 10.8 percent of those who had the operation had suffered a stroke, compared with 16.9 percent of those who were not operated on, the researchers found.
In addition, over the years of the study, patients in both groups were also taking cholesterol-lowering drugs. Even these medications did not affect the benefit of the surgery, the researchers said.
“This trial took more than 15 years to complete, because we wanted to know about the long-term effects of surgery,” Halliday said in a statement.
“The finding that successful carotid artery surgery can substantially reduce the stroke risk for many years is remarkable, because it means that most of the risk of stroke over the next five years in patients with a narrowed carotid artery is caused by that single carotid lesion. The definite benefits that we have found will be of practical value to doctors and patients deciding in the future whether to take the immediate risk of having such surgery,” she said.
The rates of stroke were reduced from about 2.2 percent a year to 1.4 percent a year over five years and from 1.8 percent a year to 1.3 percent a year over 10 years, he said.