Apple released WatchOS 5.1 today and with it comes the enabling of the Apple Watch Series 4’s electrocardiogram feature. The EKG app (or ECG, as Apple refers to it) is FDA-approved in the US and is design to detect heart rhythms and classify irregular rhythms, like atrial fibrillation. All that data will be stored in the Apple Health app.
Essentially, EKG is more accurate than heart rate monitors, partially because the wrist isn’t always the best place to take an accurate measurement. An EKG can be used to more accurately diagnose or monitor heart disease, too.
Aside from the EKG, WatchOS 5.1 includes audio support for group FaceTime calls and some new watchface customization options.