According to research published in the Annals of Internal Medicine, the Apple Watch series 4 and 5 app recorded similar ECG results to a standard ECG.

To record an ECG on an Apple Watch, users open an ECG app and use their finger to touch the digital crown — a button on the side of the device. The device then records 30 seconds of a single-channel ECG, which is similar to a lead I ECG, according to the report.

Once recorded, an app on the iPhone connected to the user’s Apple Watch does a rhythm analysis and classifies the recordings as a sinus rhythm, bradycardia, tachycardia, atrial fibrillation or inconclusive.