WatchOS 5.1.2 will present an ECG application developed by Apple, which may indicate whether your heart rate has signs of atrial fibrillation, a severe irregular heart rate, or a normal sinus rhythm. According to the FDA, the Apple Watch Series 4 can generate an ECG similar to a single lead electrocardiogram.
ECG and other heart data are collected in the Health app on a paired iPhone. The Apple document states the minimum requirement for iPhone 5 or later iOS 12.1.1, currently in beta testing, or later.
To listen to an ECG reading from Apple Watch, users will need to place a finger on the digital crown while wearing the watch. The reading is completed in 30 seconds, which allows users to determine if their hearts are beaten with a regular pattern or if there are signs of atrial fibrillation.
The Apple training document states that the ECG application is regulated and available only in regions cleared for use. Initially, the application will be limited to the United States, where Apple received FDA approval, but Apple Watch Series 4 models sold worldwide include an electric heart rate sensor for future expansion.
Apple Store employees are instructed to advise clients that the ECG application “is not intended to diagnose or replace traditional diagnostic methods” and “should not be used to monitor or track illness or replace drugs without first talking with the doctor,” according to Apple.
Apple promised that the ECG application will be available later this year, but it is unclear when watchOS 5.1.2 and iOS 12.1.1 will be released. watchOS 5.1.2 is in beta testing since November 7, and iOS 12.1.1 is working with beta testing since October 31, therefore both software updates should be released relatively soon.
A separate Apple training document received by MacRumors suggests that irregular heart rate notifications will also be included in watchOS 5.1.2 in the Apple Watch Series 1 via the Apple Watch Series 4.
The ECG application will not be available on previous-generation Apple Watch models, including the original through the Series 3.