A year after Apple launched the ECG app on Apple Watch Series 4, the feature is finally being launched in India. Designed to help Apple Watch users identify early signs of warning, the feature has helped save lives of many.

The ECG app and irregular heart rhythm (IRN) notification feature will help users identify signs of AFib, the most common form of irregular rhythm. The feature is already live for Indian users and the same can be accessed by updating Apple Watch Series 4 to watchOS 6, available starting September 19. The ECG app will be preinstalled on the new Apple Series 5 that will be available in India starting September 27.

To enable these new heart features, users will be taken through an onscreen setup flow that includes details about who can use these features, what the features can and cannot do, what results users may get, how to interpret those results and clear instructions for what to do if users are feeling symptoms that require immediate medical attention.

These health features are specialized ones. And as each market is different, it requires a lot of backend work that needs to be put in place. When such services are launched, the idea is to offer a completely sorted and seamless experience. People familiar to the matter revealed that certain authorities were consulted before rolling out these features in India.

How ECG app works

The ECG app that now appears on Apple Watch Series 4 and later running watchOS 6 in India, can be used to measure an ECG. This is a user-initiated process and takes around 30 seconds to record an ECG, which is similar to a single-lead reading. Apple had built-in new electrodes into the back crystal and Digital Crown of the Apple Watch Series 4 or later, that work together with the ECG app to enable customers to take an ECG. To take an ECG recording at any time or following an irregular rhythm notification, users can launch the ECG app on the Apple Watch and hold their finger on the Digital Crown. As the user touches the Digital Crown, the circuit is completed and electrical signals across their heart are measured. After 30 seconds, the heart rhythm is classified as either AFib, sinus rhythm or inconclusive. A sinus rhythm result means the heart is beating in a uniform pattern between 50 and 100 BPM. An AFib result means the heart is beating in an irregular pattern between 50 and 120 BPM.

Apple says that if a user receives an AFib classification and have not been diagnosed with AFib, they should consult the doctor. While taking an ECG, users can even add what prompted them to take an ECG and the data is stored in the Health app on the iPhone. A PDF of the results can also be shared with the physicians.

Unlike ECG, the irregular rhythm notification feature works in the background. It uses the optical heart sensor to occasionally check the user's heart rhythm in the background for signals of irregular heart rhythm. If irregular heart rhythm such as Afib is identified on five rhythm checks over a minimum of 65 minutes, a notification will be generated to alert the user.

Apple says that the ECG app's ability to accurately classify an ECG recording into AFib and sinus rhythm was validated in a clinical trial of around 600 participants. The study found the ECG app on Apple Watch demonstrated 98.3 per cent sensitivity in classifying AFib and 99.6 per cent specificity in classifying sinus rhythm in classifiable recordings.

When launched in September last year, the feature was first rolled out in the US post-FDA approval. While Apple Watch is available in many countries across the world, the ECG feature is available in about just 30 countries.