Apple Watch Series 4 can inspire you to live a healthier life by helping you understand everything from how many calories you’ve burned to the impact of taking a moment during a busy day to breathe. At the same time, it can monitor your heart rate and let you know if it detects something of concern.

Now, with the ECG app, Apple Watch Series 4 is capable of generating an electrocardiogram—a breakthrough for a wearable device. This can provide critical data for doctors—and peace of mind for you.

How to use the ECG app on your Apple Watch

An electrocardiogram (also called an ECG or EKG) is a test that records the timing and strength of the electrical signals that make the heart beat. By looking at the results, a doctor can gain insights about your heart rhythm and look for irregularities.

To try it, open the ECG app and place your finger on the Digital Crown. The app will generate an ECG waveform in just 30 seconds and can indicate whether your heart is beating in a normal pattern or shows signs of atrial fibrillation—the most common form of irregular rhythm.

You can take an ECG at any time, when you’re feeling symptoms such as a rapid or skipped heartbeat, when you have other general concerns about your heart health, or when you receive an irregular rhythm notification.

How to share your ECG results with your doctor

You’ll find the results of your ECGs in the Health app on your iPhone—complete with your ECG waveform, its associated classifications, and any symptoms. To share a PDF of these results with your doctor, open the Health app, tap the Health Data tab, then tap Heart > Electrocardiogram (ECG).

Select one of the ECG results listed, then tap Export a PDF for Your Doctor.