2 How to Use It on Apple Watch
While setting up the ECG feature for the first time, you’ll be asked to take an ECG reading on your Apple Watch. To do so, you’ll need to tap on the ECG app icon in the app grid. Apple notes that the Apple Watch should be snug on your wrist for this to work.
To actually take an ECG reading, you’ll simply hold your finger down on the Digital Crown for 30 seconds (there’s a helpful countdown timer). When you’re all done, simply tap Done. This is also exactly how you’ll take an ECG in the future — open the ECG app and hold your finger on the Digital Crown.