The verge has released an article stating that watchOS 5.1.2 will be publicly released today and enable the ECG app on Apple Watch Series 4 models, however the article has since been removed from their website which is possibly because it was embargoed information.

Yesterday we saw iOS 12.1.1 release to the public and so all eyes are now on the latest watchOS 5.1.2. The update will also include irregular heart rate notifications for the Apple Watch Series 1 – Series 4.