Anti-Stroke Surgery Gets Closer Scrutiny : Medicine: Carotid endarterectomy is a relatively common treatment. But surgeons are finding that it may not be for everyone.

A popular surgery to help prevent strokes is coming under scrutiny because of the lack of demonstrated benefits for some patients.

Carotid endarterectomy clears out the artery running to the brain and is among the most commonly performed surgical procedures in the United States, according to Murray Goldstein, director of the National Institute of Neurological Disorders and Stroke. An estimated 100,000 Americans will undergo the procedure this year at a cost of more than $2 billion.

There’s no question that the surgery helps those who have severely blocked carotid arteries and are experiencing the early warning signs of stroke. But Goldstein and other specialists at a recent international meeting on stroke here underscored that the popular surgery is of “unknown value” to thousands of others.

Last year, the findings from two major studies of carotid endarterectomy proved so compelling that the National Institutes of Health issued a clinical alert to physicians informing them of the operation’s benefits for patients who had blockages of more than 70% and experienced such stroke symptoms as temporary blindness, speech loss and brief weakness along one side of the body. These brief episodes are called transient ischemic attacks, or TIAs.

There’s no doubt, Goldstein said, that “we are able to identify one group of people who should benefit from this surgery.” One study showed that for these patients, carotid endarterectomy “cuts the risk of stroke by about 17%,” said Henry J. M. Barnett of the John P. Robarts Institute in London, Canada, who headed up one of the studies evaluating the surgery.

But studies have shown that the operation is of no benefit to those with small obstructions, blocking 30% or less of the carotid arteries. There’s also no evidence that the surgery can help the large number of patients whose obstructions choke from 30% to 70% of the vessel.

Several randomized national trials, sponsored by the NIH, are under way to test the safety and effectiveness of surgery in these patients.

Two conditions can cause a stroke: A blood vessel in the brain bursts, or a small piece of cholesterol-rich plaque or a blood clot breaks free and lodges in a vessel supplying blood to the brain. Deprived of oxygen, this area of the brain quickly dies.

The result can be paralysis, blindness, speech loss or death, depending on which part of the brain is affected. Roughly 15% to 20% of the nearly 500,000 strokes that occur annually in the United States are caused by a blocked carotid artery, said Barnett.

Local physicians said they are carefully evaluating patients with carotid obstructions. However, many said surgery is a common treatment.

“Where I think that everybody has appropriately become more conservative is in treating the asymptomatic patient with a narrowing carotid artery,” said Bruce Perler, director of the vascular surgery service and diagnostic laboratory at Johns Hopkins Medical Institutions in Baltimore. “Ten years ago, we thought that someone with a 50% narrowing (but without symptoms) was an ideal patient for surgery. Now we do it at 75% narrowing.”

Stanley Cohan, Georgetown University professor of neurology, said doctors are still challenged by the patient whose blockage falls in the mid-range but has no symptoms. “It’s not clear what to do there,” he said. “I have a bias, and my bias is probably to do the operation. But you don’t know what the relative risk is in surgery.”

For those who don’t qualify for surgery, there are medical options to help reduce the risk of stroke. Doctors routinely prescribe daily aspirin, which cuts the incidence of stroke in those with blocked arteries. Keeping blood pressure in check also helps, as does the administration to some people of anti-coagulants, which reduce blood clot formation.

Last December, the Food and Drug Administration approved the stroke-preventing drug, Ticlid, for use in the United States. It offers a new option to those who can’t take aspirin, said Thomas R. Price, director of the Stroke Service at the University of Maryland Hospital in Baltimore.

“Compared to where we were five years ago in preventing strokes, we are light years ahead,” Price said.