Heart Device May Cut Stroke Risk in Those With Irregular Heartbeat: Study

Mesh implant keeps clots that can form in left heart chamber from traveling to the brain, researcher says

Monday, November 17, 2014

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SUNDAY, Nov. 16, 2014 (HealthDay News) -- A new implanted heart device might be more effective than blood-thinning medications in reducing stroke risk for people suffering from the heart rhythm disorder known as atrial fibrillation, researchers report.

The device called WATCHMAN proved better than the commonly used anti-clotting drug warfarin in preventing strokes, blood clots and deaths among atrial fibrillation patients, the study found.

"These are important outcomes," said study author Dr. Vivek Reddy, a professor of cardiology at the Icahn School of Medicine at Mount Sinai in New York City. "There are very few cardiovascular interventions that show reduced mortality, and this is one of them."

The findings could lead to final federal approval for the device, which has been under review by the U.S. Food and Drug Administration for several years, Reddy said.

An FDA advisory panel gave the device a positive vote in October. "It likely will be approved, and will be available for use in the United States in the first half of 2015," Reddy said.

The findings will be published Nov. 19 in the Journal of the American Medical Association, and they are to be presented Sunday at the American Heart Association annual meeting in Chicago.

Atrial fibrillation is an electrical disorder of the heart that causes it to beat irregularly. The off-tempo beats allow blood to pool and clot in the heart, which increases a patient's risk of stroke, according to the U.S. National Institutes of Health.

The WATCHMAN device is a fabric-and-metal mesh umbrella that doctors insert through a tube into the upper left chamber, or left atrium, of a patient's heart. It is made by the firm Boston Scientific, which paid for the clinical trial and provided financial support to Reddy and other co-authors of the study.

The device covers the left atrial appendage, an ear-shaped muscular pouch located high in the upper part of the left atrium. Previous studies have suggested that the left atrial appendage is the major source of stroke-causing blood clots in patients with atrial fibrillation, researchers said in background information.

The mesh is designed to screen off the clots, preventing them from circulating through the body. "Eventually it becomes completely clotted behind the device and heals over," Reddy explained.

The WATCHMAN device could be an alternative for people who either aren't medically allowed to take blood thinners or who don't want to take the medication.

People who take warfarin must have their blood coagulation constantly monitored, as well as keeping track of multiple interactions the drug can have with other medications and food, according to background information in the article. About two out of every five patients who could take blood thinners do not, leaving them at substantial risk for stroke.

This clinical trial involved 707 patients with atrial fibrillation and at least one additional stroke risk factor. Of those patients, 463 received a WATCHMAN implant while the rest took warfarin.

After nearly four years, about 8.4 percent of the WATCHMEN patients had suffered a stroke, blood clot or death, compared with 13.9 percent in the group taking warfarin.

Patients with the device also had lower rates of heart-related death (3.7 percent versus 9 percent) and death by any cause (12.3 percent versus 18 percent) than patients taking warfarin.

But patients with the device also had a slightly higher number of adverse side effects compared with the warfarin patients, said Dr. Alfred Bove, cardiologist and professor emeritus of medicine at Temple University School of Medicine in Philadelphia.

The most common side effect was dangerous fluid build-up around the heart, the study noted.

Bove said he is concerned there could be a dramatic increase in complications related to the device if it becomes widely used by cardiologists with varying degrees of ability.

"It takes a certain amount of skill to insert this device," Bove said. "If you're a patient, don't go to your usual guy down the street and ask him to put one of these things in. Do a little research and find a skilled doctor."

Reddy agreed that patients with the device had more complications, but argued that patients taking warfarin are at higher risk for long-term health problems.

"With drugs, you have a cumulative risk that never ceases. One person may decide that one risk is better than the other risk. It's a matter of preference for individual patients," Reddy said. "The point is, we have an alternative to blood thinners in people we're trying to protect from stroke."

SOURCES: Vivek Reddy, M.D., professor, cardiology, Icahn School of Medicine at Mount Sinai, New York City; Alfred Bove, M.D., Ph.D., professor emeritus, department of medicine, section of cardiology, Temple University School of Medicine, Philadelphia; Nov. 19, 2014, Journal of the American Medical Association; Nov. 16, 2014, presentation, American Heart Association annual meeting, Chicago

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