“Doc, how’s my ticker?” In olden days (like 5 years ago), patients went to their general practitioners with such anxious inquiries, looking for cardiac checkups and reassurances. These days, consumers can buy a heart monitor that’s about the size of a piece of gum and stick it on the back of their smartphone, then check their heart rate as often as they like.
But how good are the results from such a consumer gadget? A new study that tested the Kardia Mobile heart monitor, made by AliveCor, found that the device detected more cases of the dangerous heart condition atrial fibrillation than general practitioners offering routine care.
For the study, published in the journal Circulation, researchers in Wales enrolled 1000 patients aged 65 and above. Half of the patients received routine medical care from general practitioners, the other half were instructed to use the Kardia monitor twice a week to take 30-second recordings of their heart rate. During the 1-year study, the Kardia diagnosed 19 patients while the doctors diagnosed 5.
To use the Kardia device, the user presses two fingers of each hand against an electrode pad. The device records an electrocardiogram (ECG or EKG) by detecting the subtle electrical changes in the skin that reflect the heart muscles’ electrical pattern. The display shows users their heart rate, and the device can also upload the results to the cloud for a doctor’s review. AliveCor CEO Vic Gundotra notes that the Kardia is FDA cleared: “This is not a Fitbit, this is a clinical grade device, so you can be confident in its results,” he says.
Atrial fibrillation (AFib) is a condition where the heartbeat becomes erratic and the upper chambers of the heart quiver and shake. If there’s a lurking blood clot, this shaking can break it loose and send it up through the blood vessels to the brain, where it can cause a stroke. People with AFib have a 5 times greater likelihood of having a stroke, and doctors typically put patients with the condition on blood-thinning medications that prevent clots.
But the condition can go undiagnosed for years, says AliveCor’s Gundotra, because about 40 percent of people with AFib don’t exhibit any symptoms. “Unless you think you have a problem or your doctor thinks you have a problem, you won’t be checked,” he says.
In routine medical care, a patient who’s suspected of having AFib is referred to a cardiologist for an ECG recording, in which 12 electrodes are placed on the patient’s chest and limbs. But even patients who are thought to be at risk of AFib might only be checked by a cardiologist once or twice a year. Those infrequent tests might not diagnose patients who have a form of the disorder called paroxysmal AFib, in which the heart arrhythmia comes and goes.
Of the 19 patients diagnosed with AFib via the Kardia device in the new study, 12 had paroxysmal Afib, and 8 had no symptoms at the time of diagnosis. All 19 were started on blood-thinning medications. The study wasn’t intended to compare clinical outcomes between the two patient groups, but the authors write that a future study should examine whether remote ECG monitoring leads to fewer strokes.
For the study, the twice-weekly ECGs recorded by patients were analyzed automatically by AliveCor’s software. But the paper notes that abnormal ECGs were sent to a cardiologist for review, and also says that the Kardia produced some false positives (indications of AFib that the reviewing cardiologists found to be false). For now, at least, there's still a need for a human in the loop.
The study was led by Julian Halcox, chair of cardiology at the Swansea University Medical School in Wales, who did not respond to a request for comment on the research. Halcox has no financial relationship with AliveCor.
While the Kardia device got good marks from the study’s participants for being easy to use, even this small device could be rendered obsolete by future gadgetry. Apple has announced that its Apple Watch will soon sport a better built-in heart rate monitor and app, and Stanford researchers plan to test the Apple gear soon for AFib detection. Before long, it may be common for people to wear their hearts on (well, under) their sleeves.