How to Use an Apple Watch ECG

If you have an Apple Watch Series 4, Series 5, or Series 6, use the ECG app to check your heart rate and rhythm without an iPhone, essentially performing an electrocardiogram. The ECG app uses your wearable's electrical heart sensor to detect potential problems, such as atrial fibrillation (AFib). Here's how to use the ECG app on your Apple Watch.

Set Up the Health App's ECG Feature

Before you begin, you'll need to make sure the ECG feature on your paired iPhone's Health app is set up. If this is your first time using the Health app, you'll be prompted to complete all setup instructions, including the ECG app setup.

If you haven't yet set up the ECG app in your Health app, tap Browse > Heart > Electrocardiograms and then tap Set Up ECG App.

How to Take an ECG Reading on Your Apple Watch

Fit your Apple Watch securely to the wrist you selected in Settings, and then follow these steps:

1. Open the ECG app on your Apple Watch.

2. Relax the arm that's wearing your Apple Watch and rest it on a table, desk, or your lap.

3. Using the hand not wearing the watch, hold your finger on the Digital Crown for 30 seconds without pressing down.

4. Keep your finger on the Digital Crown until the countdown is complete.

5. When the ECG app is finished, the Apple Watch will display your rhythm type, heart rate, and any sign of atrial fibrillation, as well as a reminder that the Apple Watch can't detect a heart attack.

6. Tap the plus sign to add symptoms, and then tap Save.

7. You can also view your ECG results in the Health app on your paired iPhone.

What Do the Apple Watch ECG Results Mean?

The ECG reading isn't as thorough or accurate as an electrocardiogram performed by your doctor. Still, it offers a glimpse of your heart health and may detect AFib symptoms. Here's a breakdown of some of the terms you might see:

Sinus Rhythm

This is good news. Your heart is beating in a normal, uniform pattern with no problems detected.

Low Heart Rate

Apple Watch registers a low heart rate at 50 beats-per-minute (BPM) or less. The medical term for a low heart rate is bradycardia; it can be due to medical issues or medications. Elite athletes often register a low heart rate. A low heart rate reading can also be due to outside issues, such as a loose watch band. A low heart rate reading will interfere with the Apple Watch's ability to detect atrial fibrillation.

High Heart Rate

A heart rate of over 120 BPM is considered high. This condition is called tachycardia; it can be due to recent exercise, stress, alcohol, certain over-the-counter medications, or medical conditions such as heart disease or thyroid disease.

Atrial Fibrillation (AFib)

AFib means the heart is beating in an irregular pattern, which occurs when the upper and lower chambers of the heart are beating out of sync. It's important to again note that the Apple Watch's ECG isn't as accurate as one taken by a doctor and can't directly diagnose AFib. If your Apple Watch indicates signs of AFib, contact your doctor immediately. AFib can be caused by conditions such as high blood pressure or sleep apnea. It can also be caused by alcohol, caffeine, or other factors.

Inconclusive

If the Apple Watch is unable to measure your heart rate, it will return inconclusive results. This can be due to a too-loose band or too much movement while taking the ECG.

How to Set Apple Watch AFib Notifications

The ECG app lets you set up AFib notifications, so your Apple Watch will alert you if it detects a rhythm problem. This way, you don't have to take an ECG reading to get a warning about an irregular heart rhythm. Here's how to set up heart rate notifications:

1. Open the Apple Watch app on your paired iPhone.

2. Select Heart.

3. Under Set Up Irregular Rhythm Notifications, select High Heart Rate.

4. Choose a high heart rate parameter, then go back and select Low Heart Rate. Enter your low heart rate parameter.

5. You've set up notifications for irregular heart rhythm. Turn this feature off any time if you change your mind.