Since its introduction with Apple Watch Series 4, the ECG feature has only been available to Apple Watches purchased in the United States. The only way users from other regions to access the feature was to buy the device in the United States, but recent changes to the software have made it impossible to find the solution.
It seems that this will change with the introduction of watchOS 5.2. Documentation found on iOS 12.2 released earlier today that describes regulatory information for the ECG feature mentions that the feature "is available on Apple Watch Series 4 with watchOS 5.1.2 or later" for US regions, but it mentions also that "for non-US regions" is the ECG app available on Apple Watch Series 4 with watchOS 5.2, paired with iPhone 5 or later with iOS 1
Adding this mention to non-US regions with the requirement for watchOS 5.2 strongly suggest that the feature open up to several countries with the introduction of watchOS 5.2, probably later this week
Another addition to the update of iOS 12.2 is a CE mark that is Specifically for the ECG function, this suggests that the new region should consist of countries in the European Economic Area (EEA) that adopt this particular certification, including all EU countries and also Iceland, Liechte nstein and norway
The page on Apple's site listing feature has not yet been updated to reflect this change, but we expect it to be updated as soon as watchOS 5.2 is out for all customers to be made later this week.