Heart Monitoring May Prevent Some Strokes, Study Suggests
Irregular heartbeat that causes some attacks is often tough to detect, doctors say
To properly detect atrial fibrillation, patients need round-the-clock heart monitoring. The two separate clinical trials were launched to see if continuous heart monitors would be able to resolve any cases of mystery stroke.
Passman's trial, funded by heart device manufacturer Medtronic, included 441 patients who had suffered a stroke of undetermined origin.
About half of the patients received an implanted heart rate monitor the size of a computer flash drive, in a procedure that took about 15 minutes, Passman said. A wand placed next to the device automatically transmitted heart data over a phone line to the person's cardiologist.
The other half received standard post-stroke care, which involved regular doctor visits during which they received an electrocardiogram.
By the end of the implants' three-year battery life, doctors had detected atrial fibrillation in 30 percent of the patients undergoing continuous heart rate monitoring. Only 3 percent of patients receiving standard care had been diagnosed with the heart rhythm disorder, Passman reported.
"It wasn't that the patients receiving standard care weren't experiencing atrial fibrillation, it's that we weren't finding it," he said.
The other clinical trial, sponsored by the Canadian Stroke Network, had similar success.
Researchers randomly assigned half of 572 patients who'd suffered a mystery stroke to strap a portable ECG device around their waists for at least 30 days. These devices automatically recorded any irregular heartbeats. The other half (the "control" group) underwent a single 24-hour round of heart monitoring in a laboratory.
Doctors proved five times better at detecting serious atrial fibrillation in the stroke patients who wore the portable device. They found atrial fibrillation lasting longer than 30 seconds in 16 percent of the stroke patients wearing the monitors, but only detected the problem in 3 percent of patients in the control group, the researchers reported.
Overall, the study found that atrial fibrillation of any length was detected in about 20 percent of patients wearing a monitor, compared to 5 percent of control patients.
While calling the trial results "a promising advance," cardiologist Dr. Hooman Kamel of Weill Cornell Medical College in New York City noted that the heart monitors still failed to find a cause for most of the mystery strokes.