Study links use of brain stents to more strokes
Findings raise questions about FDA process
A promising but expensive device to prop open blocked arteries in the brain in the hope of preventing disabling or fatal strokes failed in a rigorous study, researchers reported yesterday. Those who got the device had so many more strokes than those assigned to control risk factors, like blood pressure, cholesterol, and diabetes, that the study was abruptly terminated.
The Food and Drug Administration approved the device six years ago on the basis of a humanitarian exemption, which did not require solid evidence that it would prevent strokes, and thousands of patients have gotten the device since, according to the study’s lead researcher. The finding that the devices more than doubled the rate of stroke or death raised serious questions about whether the FDA’s procedures for approving such a medical device ended up putting patients at risk.
Earlier, a panel at the Institute of Medicine, a major scientific group, recommended that the FDA replace its more usual regulatory system for risky devices.
Karen Riley, a spokeswoman for the FDA, said the agency was looking at the data. One issue, she said, is whether the patients in the new study were comparable to those for whom the device was approved.
If the study’s findings hold up, the approval of the brain stents “should be something the FDA is very concerned about,’’ said Larry Kessler, a former director in the FDA’s Center for Devices and Radiological Health. The agency, he added, has the authority to withdraw its approval.
Researchers said the device seemed as if it should work. Disabling or fatal strokes can be caused by brain arteries blocked by atherosclerosis, in much the same way that blocked coronary arteries cause heart attacks. So perhaps strokes might be prevented in much the same way.
That led Natick-based Boston Scientific Inc. to make a small wire cage, a stent, to hold blocked brain arteries open, similar to the ones cardiologists use. The company sold its neurovascular unit, including the Wingspan stents, to Stryker Corp. last year.
According to the National Institute of Neurological Disorders and Stroke, at least 55,000 of the 795,000 strokes occurring each year are caused by blockages in small arteries in the brain.
The FDA approved the stent in August 2005 for high-risk patients who failed medical management (a vigorous effort to control patients’ risk factors). It relied on a study with 45 patients. It was a registry study - one that had no control group that, for comparison, did not get the stent. The study found a 4.4-percent stroke rate in the first month, much better than expected without the device.
But registry studies almost invariably report better results than studies with a comparison group, said Dr. Walter J. Koroshetz, deputy director of the National Institute of Neurological Disorders and Stroke.
The study results published online yesterday in The New England Journal of Medicine were sobering. Thirty-three patients, or 14.7 percent, who got the stent had a stroke in the first month, and five died. Among those who had medical therapy, 13 patients, 5.8 percent, had strokes in the first month. One died, but not from a stroke.