Special to Medical Device Daily
HOLLYWOOD, Florida – Doctors suggested that preliminary results indicate that treating acute strokes with Boston Scientific's (Natick, Massachusetts) WingSpan stent can make the difference as to whether a patient has to be institutionalized or can go to his or her home.
"Our preliminary data is very exciting," said L.N. "Nick" Hopkins, MD, professor and chairman of neurosurgery at the University at Buffalo in New York, and director of the Toshiba Stroke Research Center. "What these preliminary results tell us is that this treatment works."
He reported at the International Symposium on Endovascular Therapy (ISET) here that of the 18 acute stroke patients treated – most of them long after the three-hour window of opportunity for lytic treatment – 12 of the patients survived, and lowered their NIH Stroke Scale scores by 6 to 8 points. "We are seeing pretty significant improvement," he said.
"If anyone comes in with a 9 or 10 in the NIH scale it is a bad stroke; it is a nursing home stroke," Hopkins said. "If we can drop that 6 to 8 points, the patient would probably look normal within a few months. That's the difference between going to a nursing home or going home."
He worked with a team of researchers and support staff led by the trial principal investigator Elad Levy, MD, also of the University at Buffalo.
Levy will report complete results of the trial at the International Stroke Conference next month in San Diego. "We received FDA approval to use the WingSpan stent in 20 cases in a pilot study," Hopkins said.
"Previously we might be able to get half the arteries open and get improvement rates in the 30% range," he said. "In our small study we are getting more like 100% of the arteries open," he said – and getting a favorable outcome in about 70% of the cases.
Hopkins said that the procedure is rapid. "From the time we put a needle into the patient's groin until we place the stent and open the artery it takes about 15 minutes," he said. He noted that the brain arteries being treated are similar in size to coronary arteries, but the arteries in the brain are far more fragile than those in the heart.
While getting patients to treatment as soon as possible is still the goal of stroke therapy, Hopkins said time is no longer that critical if proper imaging is performed. "If the CT perfusion imaging shows that the brain is viable, I really don't care how late it is – it can even be done days later," he said. "That doesn't change the fact that there is urgency but what it speaks to it that in every person there is collateral flow. That flow isn't enough to allow the cell to function, but the cells won't die until the flow decreases even further."
The Dynamic Volume CT measurement gives doctors a clear idea of where blood flow warrants placing a stent, and where to avoid opening an arties as well.
"The FDA is excited about us expanding this study to other centers," he said. "That's our next step."
Hopkins said he and stroke team members deployed a number of devices available for removing clots. "They ought to be, theoretically, the way to go because stroke is usually an embolic event rather than a plaque rupture, thrombolic event," he explained. "But what appears to happen is that the clot becomes very adherent to the wall of the artery very quickly – within hours. And the clot retrieval devices don't work. Something is probably happening with the vascular wall.
"We would get frustrated working for hours to remove a clot without success," Hopkins said. "So we kicked around the idea of putting in a stent. We tried it and it worked. We started with a coronary stent, but they don't track very well in the brain. They are too stiff and they are balloon-expandable, so you run the risk of hurting things in getting them there. But when we got them there and popped them open, it worked. Then along came neural, self-expanding stents and that worked too," he said.
Among the patients treated in the series was a 27-year-old woman who, eight weeks after a Cesarean delivery, collapsed. Her initial deficits included upper extremity and slurred speech. She left the hospital nearly normal after having the stent placed.
Hopkins said intravenous tissue plasminogen activator (tPA) appears to work in mild strokes, but overall 50% of patients are dead or disabled after three months. As the U.S. population ages, strokes are increasing. He said that the 750,000 cases a year will reach 1.2 million by 2025.
He said that since 1991, his stroke center has used or adopted medical treatment of stroke with urokinase, prourokinase, tPA, abciximab, combinations of drugs, and, more recently angioplasty, clot retrieval and stenting to open the blood vessels that have remained blocked despite use of thrombolytic agents.
"The improvements in technologies – in the type of stent and the type of catheters – are making these advances possible," said James Benenati, MD, medical director of the noninvasive vascular laboratory at Baptist Cardiac & Vascular Institute (Miami).
What makes this study interesting is that the researchers and the device maker are working with the FDA under an Investigational Device Exemption procedure, which may make the off-label use of the stent an approved usage.
"I think the use of stents in the brain to treat an acute stroke is going to be the way we go," Benenati said. The symposium is sponsored by the vascular institute.