It will be part of the watchOS 5.1.2 update.
One of the most talked about features of the Apple Watch Series 4 is the built-in ECG (electrocardiogram) that will be able to track the electrical activity of your heart. ECGs are normally done in hospitals, but the addition of this feature on the Apple Watch Series 4 makes it an ideal tool that could probably save your life.
The problem is though, ECG wasn’t supported when Series 4 was originally launched. But that will change soon as early betas for watchOS 5.1.2 now confirms that the feature has been added and activated. At the moment, the ECG app will initially launch in the US.
Apple did stress that the ECG app isn’t intended to replace real-life machines that test it so should always go to your doctor before starting any type of medication or to double-check your heart’s condition.
There is no word yet as to when watchOS 5.1.2 will roll out, but seeing as that it’s already being beta tested that time might come sooner than we think.