Artery Surgery Brings Big Drop in Stroke Risk

Surgery that removes fatty deposits from the two main arteries in the neck that supply blood to the brain can sharply reduce the risk of stroke, one of the nation’s leading causes of death and disability, the National Institute of Neurological Disorders and Stroke said Friday.

Officials at the institute, part of the National Institutes of Health, said that they have halted a $20-million clinical trial that began enrolling patients in 1987 because results have been compelling.

“This finding will be of vital interest for individuals who are at risk of stroke, and who may already know that their carotid arteries are partially blocked,” Institute Director Zach W. Hall said at a press conference.

“During the last 48 hours (we have) taken steps to inform the medical community of these important results so that they might be better able to evaluate and advise patients on the risks and benefits of surgical treatment to prevent stroke.”

Researchers said that the surgery, known as a carotid endarterectomy, lowered the five-year risk of stroke by about half, from greater than 1 in 10 to less than 1 in 20, in individuals who had not yet suffered a stroke or stroke-like symptoms but each of whom had an artery narrowed by at least 60%.

Stroke, which occurs when brain cells die because of decreased blood flow, is the third-leading killer of Americans and the major cause of disability among adults. Carotid stenosis--the condition of blocked arteries--is responsible for 75% of all strokes. There are about 500,000 to 600,000 new strokes among Americans each year. They cause 150,000 deaths.

Of the estimated 3 million Americans who have survived strokes, more than 2 million are left with crippling disabilities, such as paralysis, loss of speech or memory lapses. Stroke costs the nation about $30 million annually, according to NIH.

Carotid artery problems become more common as people age. They are caused by atherosclerosis or hardening of the two arteries, which is a buildup of fat and other materials.

The surgery, which removes fatty deposits known as plaque from the arteries, already has been proved effective in individuals who previously have had strokes and a demonstrated carotid artery blockage of 70% or more.

In this latter group, surgery reduces the estimated two-year risk of stroke by more than 80%, from greater than 1 in 4 to fewer than 1 in 10. In 1992, about 91,000 Americans underwent the procedure, which costs about $15,000 and usually requires a hospital stay of as much as four days.

The trial was directed by Dr. James F. Toole, director of the stroke center and professor of neurology at the Bowman Gray School of Medicine, Wake Forest University, in Winston-Salem, N.C. The University of North Carolina School of Public Health at Chapel Hill served as the coordinating center for the study.

The study, conducted at 39 centers in the United States and Canada, involved 1,662 men and women ages 40 to 79, each of whom had at least one carotid artery with a 60% or greater narrowing.

Among the participants, 64% had hypertension, or high blood pressure, 26% had a history of cigarette smoking, 23% had diabetes, 21% had experienced a heart attack and 25% had suffered a mild stroke or symptom that was deemed unrelated to the carotid artery involved in the study.

All participants received conventional medical assistance for their risk factors, including aspirin, counseling to stop smoking and treatment for high blood pressure, high cholesterol and diabetes. A subset of the group, 828 randomly chosen participants, also received surgery.

Researchers said the study showed that only 4.8% of the surgical group risked a stroke within five years, compared to 10.6% of the non-surgical group.

Overall, the procedure reduced the risk by 55%, they said. Men showed a 69% reduction, while women showed 16%. The investigators said that they do not yet know the reasons for the difference between men and women, although they noted that the incidence of stroke in general is much higher in men.

Only facilities that had recorded few complications when performing the carotid surgeries were allowed to participate. Researchers emphasized that the track record of success was important for patients.

They “have the perfect right to ask the surgeon what his success rate is,” said Dr. James T. Robertson, chairman of the American Heart Assn.’s stroke council.

Dr. Michael D. Walker, director of the institute’s division of stroke and trauma, which oversaw the trial, said: “When the surgery is performed to the standards set in the study, its long-term benefits clearly outweigh any short-term risks. Appropriate use of this technique has the potential for preventing many thousands of strokes every year.”

Carotid stenosis often has no symptoms, thus “most people won’t know” they have it, Toole said. However, it often can be detected during a normal checkup with a physician, researchers said.

The most common method of diagnosis is the use of a stethoscope to listen for a rushing sound, called a bruit (pronounced “brew-ee”), in the carotid artery. Some patients can hear it themselves as “a swishing sound through their ears, when their heads are on a pillow,” Toole said.

However, “dangerous levels of disease sometimes fail to make a sound and some blockages with a low risk can make a sound,” the institute said. Thus, other diagnostic tests also are often employed to diagnose carotid stenosis, the institute said.

Surgery’s Success Rate

The study involved 1,662 patients who were found to have up to a 60% blockage of one of the two carotid arteries in the neck and who were experiencing no symptoms from the reduced blood flow. Half received one treatment and half the other.

Projected strokes within 5 years

Treated with aspirin and surgery: 4.8%

Received aspirin alone: 10.6%

Source: National Institute of Neurological Disorders and Stroke