I think the delay n ecg being released is Apple needs to make sure they have enough server capacity and bandwidth for everyone that will be doing an ECG every 5 sec 
Right now I have the Kardia Mobile ecg to use if I get concerned when my Apple Watch gives me a low heart rate alert.(most of them read as unclassified) I’ve had hospital ecg’s and the chogardogram where they us.e ultrasound to check your heart. I think a lot of people will give themselves heart attacks worrying about when the ecg function will be released
Right now I have the Kardia Mobile ecg to use if I get concerned when my Apple Watch gives me a low heart rate alert.(most of them read as unclassified) I’ve had hospital ecg’s and the chogardogram where they us.e ultrasound to check your heart. I think a lot of people will give themselves heart attacks worrying about when the ecg function will be released