The FDA has cleared the first medical device accessory for the Apple Watch, made by AliveCor, whose CEO is former Google+ boss Vic Gundotra. The accessory is AliveCor's KardiaBand electrocardiogram (EKG) reader, a sensor that pairs with an app and can detect abnormal heart rhythm and atrial fibrillation (AFib). The user touches the sensor, which snaps into a slot on the watch's band, to get an EKG reading in 30 seconds. The recording can then be sent to a doctor.

Using AI, the KardiaBand can predict and analyze someone’s heart rate based on data from both sick and healthy people, Bloomberg notes. “It doesn’t apply a generic range — instead, it determines what’s abnormal for you.” A device like this could play an important role in quickly diagnosing abnormalities and then alerting health-care professionals to life-threatening situations.

“Apple might be able to say ‘oh your heart rate is high’ …but what does that mean? Does that mean you should go to the hospital? And if you go to the hospital what are they going to do? Any doctor will say ‘ok come in, lets get an EKG reading’,” Gundotra told TechCrunch. “It’s not possible to diagnose atrial fibrillation without FDA clearance. That is a big, big play.” Apple has an initiative called the Apple Heart Study and plans to use heart rate data in building further research.

AliveCor also announced a new feature in its Kardia app called SmartRhythm, that uses AI to analyze data from the watch's heart rate and activity sensors. The app will evaluate the correlation between heart rate and activity, and if these appear abnormal, will alert the user to capture another EKG reading. A speech recognition function also allows patients to describe their symptoms aloud to the watch. The app will then generate analysis based on the data, which can be emailed to the user’s doctor.

KardiaBand is available now for $199, and requires a subscription to AliveCor's premium service, which costs $99 a year. The company also has a similar EKG reading device called the KardiaMobile, but that device attaches onto the back of your smartphone instead.