The ECG feature is included in watchOS 5.1.2, according to Apple Store tutorials such as MacRumors . The software update has been in beta testing for a few weeks, so it will probably be a full release in the near future. Apple has said the app should arrive until the end of the year.
It will only be available in regions where it has been deleted for use because the feature is regulated. Initially, you can only use the app if you are in the United States.
The documents tell that Apple Store employees should remind customers that the app is not "intended to be a diagnostic device or replace traditional diagnosis methods" and "should not be used to monitor or track state of illness or change medication without first talking to a play. "In addition, they state that you need an iPhone 5S or later running at least iOS 1