The ECG feature on the Apple Watch Series 4 that the company was so proud about at the announcement might be enabled in the next watchOS update, according to a recent report. Version 5.1.2 that is currently in beta will enable the Apple Watch Series 4 ECG functionality, as per an alleged internal Apple Store training document.
The watchOS update, once public, final, and pushed to devices, will contain a special ECG app. Said app will alert in case the watch detects signs of atrial fibrillation. The special ECG app will only be available on the Apple Watch Series 4, that actually has the hardware to support it.