ECG app Didnt work on my apple watch

ECG is

viewed as a medical device which mean it require official approval from the

government of a country before it's legal for apple to offer

these are

the countries which has provided with said approval so far

watchOS - Feature Availability - Apple

ECG

implies that citizens' medical data be stored by a foreign third-party company

without individual approval by the government of said country, and that is not

something all countries feel comfortable with.

if / when your government approve the feature the next watchOS update should bring the support

no or maybe

the url I posted is to a page that list countries whos government have approved ECG in their country

only if your countrys government approve ECG for use will it be work on your watch