P&S Journal: Winter 1995, Vol.15, No.1
Surgical Prevention of Stroke
A study funded by the National Institute of Neurological Disorders and Stroke (NINDS) has concluded that surgery can prevent stroke in carefully selected individuals with no outward signs of disease but who face a risk for stroke from a severe narrowing of a major artery in the neck. The NINDS brought to an early conclusion a seven-year clinical trial investigating the effectiveness of a surgical procedure, called carotid endarterectomy, in reducing stroke in these individuals. Dr. J.P. Mohr, professor of neurology and director of the Neurological Institute's Stroke Center, directed the trial site at Columbia.
The trial, called the Asymptomatic Carotid Atherosclerosis Study, found that surgery to remove fatty deposits from one of the main arteries in the neck (the carotid arteries) supplying blood to the brain lowered the five-year risk of stroke by about half, from greater than one in 10 to less than one in 20.
As part of the $20 million trial, investigators at Columbia and 38 other sites in the United States and Canada studied 1,162 men and women between the ages of 40 and 79 with a 60 percent or greater narrowing of the carotid artery but no stroke-like symptoms attributable to the blockage.
"Individuals who are suspect for having arterial obstructive disease in the arteries of the heart or leg may also have obstructive disease in the arteries leading to the brain," says Dr. Mohr, whose trial site was the study's third largest.
"It would be prudent to have the status of the arteries leading to the brain checked by a simple test like ultrasound. For those with extreme degrees of obstruction, endarterectomy is a good operation if they are suitable for tolerating surgery. I see no reason for discouraging people from having it."
Neurosurgeons or vascular surgeons who demonstrated a complication rate of less than 3 percent for symptom-free patients (based on an audit of their previous 50 consecutive carotid endarterectomies) performed surgery on 820 randomly chosen patients. The other patients were managed medically.
Trial investigators provided all patients with the best available medical care, including one adult aspirin daily and aggressive management of modifiable risk factors, including counseling to help them stop smoking and treatment for high blood pressure, high cholesterol, and diabetes.
The surgical groups experienced a much lower risk of death or stroke without warning (4.8 percent over a five-year period) compared with those managed medically (10.6 percent). Surgery conferred a relative risk reduction of 55 percent. Men in the surgical group had a 69 percent relative risk reduction, and women had a 16 percent relative risk reduction. Reasons for the difference are unknown, Dr. Mohr says.