Stents for blocked brain arteries may not be as successful in prolonging survival as believed: Study

By Dr. Ananya Mandal, MDSep 8 2011

A study out this Wednesday says that insertion of an artery-opening device called a stent into the brain to improve blood flow to prevent a second stroke may do more harm than managing high-risk patients with drugs and lifestyle changes. Blocked brain arteries caused by the build-up of fatty deposits called plaque account for more than 50,000 of the 795,000 strokes occurring in the United States each year. Stroke is the fourth-leading cause of death and a leading cause of disability in the United States.

Stroke patients in a large study who were treated with drugs and a brain stent had more than twice the rate of strokes and death in the month after surgery compared with those treated with drugs alone, researchers said.

The study, published in the New England Journal of Medicine, attempted to see if adding Stryker Corp's Wingspan stenting system to medication management improved survival in high-risk patients but found that it did not. Researchers had expected the use of stents to help the patients but a check of safety data as the study unfolded prompted the National Institute of Neurological Disorders and Stroke (NINDS) to halt the trial in April.

“This study provides an answer to a long-standing question by physicians -- what to do to prevent a devastating second stroke in a high-risk population,” said Dr. Walter Koroshetz, deputy director of NINDS, part of the government's National Institutes of Health, which funded the study. He added, “Although technological advances have brought intracranial stenting into practice, we have now learned that, when tested in a large group, this particular device did not lead to a better health outcome.”

The self-expanding Wingspan device, which widens a major artery in the brain to help improve blood flow, is the only system currently approved by the U.S. Food and Drug Administration for certain high-risk stroke patients.

Researchers studied 451 patients in 50 medical centers who had recently had a stroke or stroke-like symptoms caused by narrowing of a major brain artery. Everyone in the study was given blood-thinning drugs and treatments to lower blood pressure and cholesterol, two key risk factors for stroke. Half the patients also were treated with stents.

The researchers had expected the stenting system to cut the risk of stroke or death by 35 percent over two years. Instead, 14.7 percent of patients in the stenting group had a stroke or died within the first 30 days of enrolling in the study, compared with 5.8 percent of patients in the group that received drugs and lifestyle changes alone. The increased risk from stenting appeared to expand beyond the first month of treatment.

During a nearly one-year follow-up period that began after the first 30 days of the trial, 20.5 percent of patients in the stent group and 11.5 percent of patients in the drugs and lifestyle group had a stroke or died. Based on this information, an independent safety board recommended researchers stop adding new patients to the study. Everyone already in the trial will be followed for two years to study the long-term effects of both treatment approaches.

Marc Chimowitz of the Medical University of South Carolina in Charleston, who led the study, said the findings have immediate implications for doctors. “Stroke patients with recent symptoms and intracranial arterial blockage of 70 percent or greater should be treated with aggressive medical therapy alone that follows the regimen used in this trial as closely as possible,” Chimowitz said in a statement.

Some researchers who were part of the study said they still think there may be a place for stents. “This is certainly not the final say on managing this disease,” Dr. Michael Waters of the University of Florida, who worked on the study, said in a statement.

“The complications on the stent side of the trial were higher than we expected,” says co-principal investigator Colin P. Derdeyn, MD, professor of radiology at Washington University School of Medicine in St. Louis. “Further research may identify specific groups of patients who may benefit from these stents, but for now we seem to be able to save more lives by aggressively working to lower blood pressure and cholesterol.”

The researchers are now trying to determine why patients with the stents experienced high rates of strokes and death. Among the possibilities are blood clots forming on the stents or breaking loose from blood vessel walls. Damage to blood vessels during installation of the stents may also have increased risk.

“An earlier study found that high blood pressure and cholesterol levels in this group of patients was strongly associated with increased stroke risk,” Derdeyn says. “We developed ‘aggressive medical management’ protocols that asked treating physicians to work hard to bring patient blood pressure and cholesterol into safe ranges. We also regularly monitored patients to see if these goals were being met.”

“We only accepted patients whose stenoses blocked 70 percent or more of an artery, so this was a very high-risk group,” says Derdeyn, who is director of the Stroke and Cerebrovascular Center at Barnes-Jewish Hospital and the School of Medicine. “While we were selective in that regard, we did not investigate the nature of the blockages — for example, how much of the blockage was plaque only and how much of it was blood clot on a plaque. These patients may have different risk of stroke with stenting.”

The researchers will continue to follow the patients who have already been treated for two more years.