Medtronic Heart Monitor Spots Stroke Dangers in Study

Medtronic Inc.’s Reveal XT, a tiny heart monitor that’s inserted under the skin on the chest, detects more potentially deadly erratic heart rhythms in stroke patients than standard approaches, a company-funded study found.

The results suggest a better way to find the cause of thousands of strokes in the U.S. each year, said Richard Bernstein, a professor of neurology at Northwestern University Feinberg School of Medicine in Chicago. While the irregular heart rhythm called atrial fibrillation is one cause, the reason for more than one-quarter of the 800,000 strokes a year is unknown, the Centers for Disease Control and Prevention said.

Medtronic’s Reveal XT found 7.3 times more cases of atrial fibrillation than the current methods for detecting it, including Holter monitors and electrocardiograms, in the study released today of 441 people who had unexplained strokes. After three years, 30 percent of those getting continuously monitored with Reveal were shown to have atrial fibrillation, compared with 3 percent of those getting older approaches.

“If we can’t find the cause of the stroke, we’re just guessing at the right treatment,” Bernstein, who helped lead the research, said in a telephone interview. “If we find atrial fibrillation, we know that blood thinners are vastly more effective than aspirin and similar drugs that we usually use.”

The researchers switched most patients with atrial fibrillation to the stronger blood thinners, Bernstein said. They saw fewer subsequent strokes, though the study wasn’t designed to track that detail and the difference wasn’t definitive, he said.

‘Scariest Things’

“We have a lot more work to do to know why these people had strokes, but we have sliced off a large portion of those who were previously considered to have unknown causes,” he said. “Having a stroke is among the scariest things that can happen to anyone, and it rattles their faith. When we tell them we can watch your heart rhythm for three years, they jump at this.”

The results were presented at the International Stroke Conference in San Diego.

The device is inserted under the skin on the left side of the chest during a 15-minute outpatient procedure. It constantly monitors the heart’s electrical activity, detecting when erratic rates develop. Medtronic, based in Minneapolis, is currently awaiting U.S. approval of a smaller version of the monitor that can be injected into the patient, rather than inserted.