Apple’s Innovation with Apple Watch capabilities continues as new electrodes in the Apple Watch Series 4 enable customers to take an ECG right from their wrists.

The ECG app available now on the Apple Watch Series 4 is the first direct-to-consumer product that enables customers to take an electrocardiogram right from their wrist. The app captures heart rhythms and issues notifications if heart rhythms are irregular such as too rapid or skipped. This provides critical data to physicians with the potential to save lives. The Apple Watch already offers considerable insight into health and fitness data, through workout integrations.

Irregular Heart Rhythm Notification

Apple Heart Study Data and FDA Approval

The new irregular rhythm notification feature on Apple Watch Series 4 can check heart rhythms in the background and send a notification if an irregular heart rhythm is detected. The technology checks for irregular heart rhythms that could be linked to atrial fibrillation (AFib). Apple received De Novo classification for the ECG app and the irregular heart rhythm notification from the Food and Drug Administration (FDA) after working on the technology and features for several years to provide consumers with an over the counter option.

The Apple Heart Study recently studied the irregular rhythm notification feature with over 400,000 participants. The Apple Heart Study was the largest screening study on atrial fibrillation ever conducted, compared to prior cardiovascular trials to date. A data set of the Apple Heart Study was submitted to the FDA to support clearance of the irregular rhythm notification feature. The data set compared participant notifications of an irregular rhythm notification while simultaneously wearing an ECG patch and Apple Watch Series 4. 80 percent showed AFib on the ECG patch as compared to 98 percent showing AFib or other clinically relevant arrhythmias on the Apple Watch Series 4.

AFib Detection

The ECG app is available today as a free update to watchOS 5.1.2 and offers the irregular heart rhythm notification feature2 to identify signs of AFib. If left untreated, AFib can result in stroke, which is the second most common cause of death around the world. The CDC estimates that AFib can affect up to two percent of the younger population and nine percent of those aged 65 years and older in the US.

Consumers with Apple Watch Series 1 or later with watchOS 5.1.2 installed, will receive a notification if an irregular heart rhythm such as AFib is identified. Using the optical heart sensor in Apple Watch Series 1 or later, the irregular rhythm notification feature checks the user’s heart rhythm in the background for signs of an irregular heart rhythm that appears to be AFib. Then the watch sends out a notification to the user if an irregular rhythm is detected on five rhythm checks over a minimum of 65 minutes.

How It Works

An Apple Watch wearer can take an ECG reading with Apple Watch Series 4 at any time. New electrodes built into the back crystal and Digital Crown on Apple Watch Series 4 work along with the ECG app to enable customers to take an ECG similar to a single-lead reading. 

You can take a reading by launching the new ECG app on Apple Watch Series 4 and holding your finger on the Digital Crown. As you touch the Apple Watch Series 4 Digital Crown, the circuit is completed and electrical signals across their heart are measured. After 30 seconds, the heart rhythm is classified as AFib, sinus rhythm or inconclusive. All recordings, their associated classifications and any noted symptoms are stored securely in the Health app on iPhone. You can share a PDF of the results with physicians.

To enable these new heart features, you will go through an onscreen setup flow after installing watchOS 5.1.2 that includes details about who can use these features, feature functionality, result options and what to do if you feel symptoms that require immediate medical attention.

See our prior coverage here. With these new features, the Apple Watch goes even further in providing relevant information on a daily basis to consumers and more useful and engaging apps. Learn more about watchOS 5.1.2.