An irregular heartbeat called atrial fibrillation is a big cause of stroke, especially for people who have recently had a stroke. But it's not something that most people can feel.
Doctors test for atrial fibrillation by hooking people up to an electrocardiogram machine at the office, or having them wear a Holter monitor for a day or a week. There are also implantable monitors to check for afib, but they aren't widely used.
Learning to take your own pulse may be as effective and a lot simpler, according to German researchers.
They trained 220 older people who had had a stroke to tell the difference between a normal pulse and the fluttery abnormal rhythm of afib.
The training was considered a success if the people were able to correctly measure their pulse twice in a row; 196 people aced the test, for an 89 percent success rate.
To find out if the amateurs' measurements actually detected afib, the patients also were being continuously monitored on an electrocardiogram. But they weren't able to see the ECG monitor while doing the self-test.
It found that 57 of the patients had irregular heartbeats.
The patients who checked their own pulse rate provided reliable results 89 percent of the time. They identified irregular rhythms 54 percent of the time, and normal rhythms 96 percent of the time. They incorrectly thought they had afib just 3 percent of the time.
False positives are one downside of having people self-test, says Dr. Bernd Kallmunzer, a neurologist at Universitatsklinikum Erlangen in Germany who led the study. They typically would be told to go get an ECG test. But because there were only 6 people who thought they had afib when they didn't, "the number of 'unnecessary' ECG recordings are expect to be rather low," Kallmunzer said in an email.
Relatives also were trained to take the patients' pulses, and they did even better, identifying irregular rhythms 77 percent of the time.
The results were published online Wednesday in the journal Neurology.
"Many times people don't know they're in afib," says Dr. Ralph Sacco, chairman of the department of neurology at the University of Miami. "This group is trying to propose a more simple, cheap method that may work, having stroke patients and their caregivers monitor pulse.
"There's very little downsides other than maybe the extra anxiety if you thought there was something wrong if it wasn't," Sacco told Shots.
He can forsee the day when people would check their pulse rates the way they check their blood pressure, but notes that the test will be less useful in younger people and older people not at risk of stroke.
People with atrial fibrillation can be given medications that substantially reduce their risk of a blood clot and stroke.
Want to try it yourself? The American Heart Association has written instructions. Or check out this nifty video from the British Heart Foundation that also lets you hear the difference between regular and irregular heartbeats. Thanks to our perspicacious readers for flagging it!