https://newatlas.com/apple-watch-heart-study-irregular-heartbeat/58897/

Time can be of the essence when it comes to heart trouble, so imagine a world where you can rely on your wristwatch to notify you if something seems awry. We're certainly not there yet, but a massive new study carried out by Stanford scientists (and funded by Apple) suggests this kind of functionality isn't unattainable either, with the Apple Watch able to detect irregular heartbeats in a meaningful amount of users.