watchOS 5.1 should have activated the ECG on Apple Watch Series 4. The electrocardiogram function will only be available in the US, but changing country in the settings we can also use us Italians.
If you are losing your mind because you do not find a way to activate the ECG, you can put your soul in peace. WatchOS 5.1 has not yet enabled this feature, for anyone, not even for Americans.
We will have to wait for a next update that could take place by the end of the year or directly in January. In any case, we will keep you updated.