In addition to being able to tell time and message friends, the Apple Watch serves as a wearable health and fitness tracker: It can offer workout suggestions, monitor your heart rate, and even help detect sleep apnea in sufferers.

Now, when paired with a third-party band dubbed the AliveCor KardiaBand, it can offer something new to the Apple line: functionality as part of an FDA-approved medical device for EKG monitoring.

To be clear, the Apple Watch itself wasn’t subject to FDA approval: The company doesn’t want to slow down its development schedule by seeking the stamp of a government review process. The approval was granted to the KardiaBand wrist strap accessory, which delivers EKG monitoring that can detect signs of atrial fibrillation (heart arrhythmia) or abnormal heart rhythm by having wearers place a thumb on the band sensor and wait 30 seconds. Unusual readings can then be passed along to your doctor. (The device can differentiate between a high heart rate due to exertion and one outside the boundaries of a body at rest.)

EKG, or electrocardiography, is typically performed only in hospitals, where the heart’s electrical activity can be continuously monitored via skin-placed electrodes. Having the ability to perform the same function at home could provide early warning signs of serious complications stemming from atrial fibrillation, like a heart attack or stroke.

The KardiaBand is available now for $199. While not required, a subscription to AliveCor’s monitoring software adds cloud storage and monthly physician reports and costs $99 annually.

[h/t 9to5mac.com]