Brain stents, which are placed to open up a blocked artery and are designed to prevent strokes in high-risk individuals, actually increase the risk of stroke and death considerably, researchers reported in NEJM (New England Journal of Medicine, after completing a multi-center clinical trial. Patients receiving brain stents were found to have twice the rate of strokes and death compared to those without stents, the authors wrote.
This significant increase in stroke risk prompted the National Institute of Neurological Disorders and Stroke to stop enrollment into the trial in April 2011.
The NIH (National Institutes of Health) has alerted doctors and the general public about the results of the trial. This will probably alter treatment decisions significantly, with doctors recommending patients undergo changes in lifestyle and take certain hypertensive, blood-thinning and cholesterol-lowering medications.
The trial involved 450 patients at 50 centers throughout the USA. All of them had recently had a stroke, or temporary-like symptoms linked to considerable narrowing of a major artery in the brain. When a brain artery narrows, blood supply to the brain goes down, which significantly raises the risk of further strokes.
They were all prescribed blood-thinning medications and received aggressive therapies to control blood pressure and blood cholesterol levels. 225 of them were selected randomly to receive brain stents.
The authors report that:
- The stent patients
15% had a second stroke or died within 30 days of starting treatment.
20.5% had a stroke or died within a nearly one-year follow up period.
- The non-stent patients
Under 6% had a second stroke or died within 30 days of starting treatment.
11.5% had a stroke or died within a nearly one-year follow up period.
"The complications on the stent side of the trial were higher than we expected. 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 authors say they are now attempting to find out what is causing the stent patients to have higher stroke and death rates. They suggest that clots form on the stents and then become dislodged. Another possibility might be damage to blood vessels when the stent is installed.
In the USA, stroke is the fourth leading cause of death. Over 50,000 of the 750,000 strokes that occur in America every year are caused by stenosis. Stenosis refers to the narrowing or blockage of blood vessels caused by the accumulation of clots and plaques. Individuals with diabetes, as well as Hispanics, Asian-Americans and African-Americans have a higher risk of stenosis than other people.
The Gateway-Wingspan system, a technology that allows the surgeon to open a blocked cranial artery by inserting a balloon into it and inflating it, is the only FDA-approved device that is dedicated to blocked arteries in the brain. The balloon is inflated, after which the stent is inserted to keep the artery open.
Mark Chimowitz, MBChB, from the Medical University of South Carolina in Charleston, and Derdeyn set out to determine what the risk and benefits might be for the Gateway-Wingspan in a randomized clinical trial. They designed the Stenting vs. Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis.
"An earlier study found that high blood pressure and cholesterol levels in this group of patients was strongly associated with increased stroke risk. 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."
The human study started in 2008.
Derdeyn, who is also director of the Stroke and Cerebrovascular Center at Barnes-Jewish Hospital and the School of Medicine, said:
"We only accepted patients whose stenoses blocked 70 percent or more of an artery, so this was a very high-risk group. 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."
They added that that kind of information which is potentially obtainable through modern scanning techniques, could help researchers and other doctors caring for these patients to better targeted treatment plans.
Those who have already been treated will be followed for another 24 months.
Written by Christian Nordqvist