More Americans will have medical devices deployed in vessels near their brains to fish out debilitating blood clots thanks to changes in the national guidelines for treating stroke patients.
Clot-removal devices recommended for some stroke patients
Medtronic makes one of two devices approved for use in the U.S. for removing blood clots.
June 29, 2015 at 11:41PM
The new guidelines, announced Monday by the American Heart Association (AHA), recommend that patients with the worst kinds of strokes be treated with medical devices like one designed in Minnesota to break up blood clots. The devices are used in combination with clot-busting drugs.
It's the first time that consensus guidelines for stroke recommend using a medical device to remove a clot that kills brain cells by cutting off blood supply. It follows half a dozen studies in recent years that sought to measure the benefit of using devices along with drugs, rather than drugs alone.
The change is intended to improve stroke survival rates while cutting the percentage of patients who emerge from the hospital debilitated because a clot has caused permanent brain damage. Strokes are the No. 5 cause of death in the U.S., but the top cause of disability.
"If you can get someone back to functional independence who was going to be debilitated and reliant on a caregiver … that is a huge win across the board," said Brett Wall, president of Medtronic's Neurovascular division, which makes a clot-removal device.
Only two so-called stent retriever devices are approved in the United States: Medtronic's Solitaire, which was originally designed by Plymouth firm ev3; and the Trevo ProVue Retriver, made by Michigan-based Stryker Corp.
"There is now overwhelming evidence that treatment of the largest, most devastating type of stroke requires emergent endovascular intervention in addition to" clot-busting drugs, North Carolina stroke specialist Dr. Donald Heck said Monday in news release distributed by Stryker.
However, access to the best stroke care remains a challenge.
Only 4 percent of acute stroke patients are even treated with the recommended IV medications in the hospital, even though 81 percent of the population lives within an hour of a hospital capable of giving them, according to a study published last August in the AHA journal Stroke.
"We're still only treating 4 percent. We haven't changed that. So 96 percent of people in Minnesota who are having a stroke are still not being treated," said Dr. Andrew Grande, a neurosurgeon with the University of Minnesota. "This is more of a win to develop new devices and explore new therapies than anything else."
The Stroke journal study found less than 1 percent of those same patients received an endovascular therapy like a mechanical clot-removal.
About 800,000 Americans have a stroke each year, and 137,000 die from it, the AHA says. About 60 percent of the fatalities are in women. African-Americans have a much higher risk of having a stroke, and dying from it, than whites.
On Monday the AHA said that patients who have an acute stroke involving a blood clot stuck in one of four large arteries is a candidate for mechanical clot-removal. The larger vessels — the carotids on either side of the neck and the proximal middle cerebral arteries — are recommended for use because they're large enough to accommodate the medical tools.
The devices themselves consist of long wires tipped with meshes. The wires are fed into the brain's major arteries through a winding vascular route that begins with a small incision in the leg. The mesh can then be deployed by the physician to capture the clot and pull it back out.
Important caveats apply. First, the new guidelines only recommend doing a mechanical thrombectomy procedure if the patient first gets an intravenous dose of a drug called a tissue plasminogen activator (IV-tPA) within 4.5 hours of symptoms.
The mechanical procedure should be used within six hours of symptoms, and only after imaging shows less than half the affected side of the brain is not permanently damaged by loss of oxygen.
The guidelines say the devices are recommended to treat an acute severe stroke, but Grande noted that patients won't necessarily know what type they have when the feel facial droopiness or inability to lift their arms. The more important factor is that people learn about the signs of stroke and seek attention at a center qualified to treat it.
"If you are having a stroke, you are not going to know whether it is a major or minor stroke," he said. "Time is critical. You need to get to the hospital right away."
Joe Carlson • 612-673-4779
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