Study finds the Apple Watch can track atrial fibrillation with 97% accuracy

There has been plenty of scepticism about what wearables can do for healthcare. While there have been individual cases of Fitbits saving lives, such news stories tend to be notable because they’re so rare, rather than as indicative of a sea change in health technology.

The Apple Watch has previously been found to have the most effective heart rate tracking – albeit, significantly better when the subject is resting than exercising. This accuracy has now been utilised in a medical context, proving incredibly effective at spotting atrial fibrillation – a condition that makes you five times more likely to suffer from a stroke, but is often symptomless.

The researchers found that the Apple Watch’s free Cardiogram app can be used to distinguish atrial fibrillation (AF) from a regular heartbeat with accuracy that compares pretty strongly to a 12-lead electrocardiogram reference. After training a deep neural network with 139 million heart rate measurements from over 6,000 Cardiogram users, the app was tested on a selection of 51 patients due to undergo treatment for AF. Wearing an Apple Watch for 20 minutes before and after cardioversion, the researchers found the watch capable of spotting AF with an accuracy of 97%, a sensitivity of 98% and a specificity of 90.2%.

“Our results show that common wearable trackers like smartwatches present a novel opportunity to monitor, capture and prompt medical therapy for atrial fibrillation without any active effort from patients,” the study’s senior author Gregory M. Marcus, the director of clinical research for the cardiology division at the university of California, San Francisco. “While mobile technology screening won’t replace more conventional monitoring methods, it has the potential to successfully screen those at an increased risk and lower the number of undiagnosed cases of AF.”

That would certainly be useful, though in the greater scheme of things, any such remote diagnoses would only be effective for a minority of the population for one very clear reason: wearables just ain’t that popular. Apple is at the top of the tree, however: while the company hasn’t released any sales figures of late, Canalys estimates the company sold 11.9 million watches in 2016. That’s impressive, but considering only 0.5% of the world’s 7.5 billion population are estimated to have AF, the Apple Watch is unlikely to catch too many of them.