When I was a kid, the most sophisticated feature of a watch was that it claimed to be wearable underwater without breaking.
I briefly thought of that and how much has changed as I read the preliminary results of the Apple Heart Study, which were published today by Stanford Medicine researchers. It found that Apple Watches can help detect atrial fibrillation (AFib), a condition that contributes to an estimated 130,000 deaths each year in America.
AFib is characterized by an irregular heartbeat. But it’s often an intermittent condition—the heart doesn’t always beat irregularly—and its symptoms can seem unrelated to your heart, making it frustratingly difficult to detect and diagnose; an estimated 700,000 Americansdon’t know they have AFib. That’s what makes a smartwatch an ideal measurement tool: it periodically collects pulse data in the background throughout the day.
The Apple Heart Study enrolled more than 400,000 participants—a population larger than New Orleans— who downloaded an app and had pulse data from their Apple Watch analyzed by Stanford Medicine researchers. Those with a sufficient number of irregular pulse readings were notified to see a doctor and also sent electrocardiogram (ECG) patches, which record the electrical rhythm of the heart to support an AFib diagnosis.
Among the study’s many encouraging findings, three in particular stood out to me.
First, 99.5% of participants didn’t receive any notification at all. That’s good news, and it also helps address concerns about “over-notifying” people and sending them to doctors unnecessarily.
Second, comparisons between irregular pulse-detection on Apple Watch and simultaneous electrocardiography (ECG) patch recordings showed that eighty-four percent (84%) of the time, participants who received irregular pulse notifications were found to be in atrial fibrillation at the time of the notification. Essentially, these participants registered an irregular heartbeat while wearing both their Apple Watch and the ECG patches, allowing researchers to see if the two readings lined up. More than eight of ten times they did, demonstrating that their pulse data could be useful in informing an AFib diagnosis.
And finally, one-third (34%) of participants who received irregular pulse warnings and used an ECG patch several weeks later were found to have AFib. These were people who weren’t wearing an ECG patch at the exact time of their notification, but did eventually. To put the 34% into context, remember that AFib can display intermittent symptoms, so it’s not surprising for it to go undetected in subsequent monitoring. If anything, this figure reinforces the importance of developing tools that monitor our heart consistently in the background.
I’m as excited about what the study found as the new questions it leaves open for exploration. Will people actually visit a doctor if notified they should do so? How do we impact this number? How do we design a health care system that easily integrates new tools like smartwatches into preventive medicine? And how can wearable technology be used to advance health in other areas?
As we answer these—and other—questions, we take yet another step toward high tech enabling high-touch care, opening new possibilities for how we diagnose, treat, and ultimately prevent disease.