Intracranial Stent Shows Promise in Real-Life Registry
SAN FRANCISCO – Using an intracranial stent made of a flexible metal alloy, neurointerventionalists are successfully reaching stenotic artieries deep within the brain.
So suggests a review of a NIH-sponsored multicenter registry that shows the stent, known as Wingspan, was deployed at the target area of less than 50 percent residual aperture in 97 percent of cases.
Until a randomized controlled trial is performed, however, it is too soon to know whether the stent is more effective than medical therapy with aspirin or warfarin, said Osama O. Zaidat, MD, associate professor of neurology at the Medical College of Wisconsin in Milwaukee.
Before treatment, the patients all had 70 percent to 99 percent stenosis of intracranial arteries, creating a particularly high risk of stroke, he said.
The registry data showed that with stent treatment, 13.8 percent of patients had a stroke or died within 30 days, or had an ipsilateral stroke between 30 and 90 days. This was slightly but not significantly lower compared to the 15.8 percent rate associated with medical therapy in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) Trial, according to Dr. Zaidat.
The 8.4 percent rate of death, stroke, or intracranial hemorrhage at 30 days in the registry is comparable to the 9 percent rate observed in the clinical trial data that led to FDA approval, he added.
The study shows some potential benefit, Dr. Zaidat said, but comparison of the confidence intervals of the stroke rate in this registry and WASID does not provide conclusive evidence — one way or the other — whether stenting has an advantage over medical therapy.
In 2005, the FDA granted Humanitarian Device Exemption approval of the Wingspan stent – manufactured by Boston Scientific — making it the first and only approved intracranial stent, he said.
The new NIH-funded study offers the first snapshot of the real-world safety and technical success of Wingspan, Dr. Zaidat said. But since only 131 patients have been enrolled in the registry and only 25 percent have been followed for more than six months, the results should be interpreted cautiously, he said at a late-breaking session here in February at the 2007 International Stroke Conference sponsored by the American Stroke Association.
As for safety, 4.6 percent of patients had a stroke or intracerebral hemorrhage or died within 24 hours of stent placement, he said, and 24.5 percent of patients re-stenosed at four months.
Dr. Zaidat noted that Wingspan is a bare metal stent. “When we come up with a new generation of drug-eluting stents, which are commonly used for cardiac disease, we think that will further lower the rate of re-stenosis,” he said.
For years, efforts to maneuver stents into the delicate brain blood vessels generally failed, he explained, because physicians were using the same stents they used to open occluded heart arteries. Designed for the sturdier cardiac vessels, the stents were too thick, stiff, and rigid for the narrow arteries deep within the brain.
Commenting on the findings, Philip B. Gorelick, MD, John S. Garvin Professor and head of the department of neurology and rehabilitation at the University of Illinois in Chicago, said that the Wingspan stent is a “technological tour de force.”
“We generally believe that by opening up the blood vessel in an appropriate time frame and allowing blood to reperfuse the area, the patients will do better,” he said.
That said, a randomized controlled trial to determine whether the stent is superior to medical treatment is needed, said Dr. Gorelick.
Robert J. Adams, MD, Presidential Distinguished Chair and Regents Professor of Neurology at the Medical College of Georgia, in Augusta, said: “The data are encouraging. But while technical feasibility is necessary, it is not sufficient to adopt use of the stent in routine practice.”
He noted that, unlike drugs, devices can be approved solely on safety data, without a randomized controlled trial proving efficacy.
“It is crucial for neurologists to support trials to test this and other devices,” Dr. Adams said.
ARTICLE IN BRIEF
✓ An intracranial stent made of a flexible metal alloy is enabling neuro-interventionalists to reach stenotic artieries deep within the brain, but until a randomized controlled trial is performed, experts say it is premature to say whether the stent is more effective than medical therapy with aspirin or warfarin.