I have an Apple Watch 4, but I use an app that my doctor told me about a couple of years ago. You can see what it is like by going to alivecor.com.
I like it because it fits on my iPhone and I can get a reading by a board certified cardiologist if I want to for $19.00.
Of course it is only one lead, they also have a band that can go on your Apple Watch. I think the Apple Watch only records for 30 seconds( I don’t really know because I have not used it).
I am 77 years old and have had many kinds of irregular heartbeats for years, so hang in there and go to the web page for alivecor and see what you think, it is cheaper than the Apple Watch and I think it is better. They are also working on a 6 lead EKG.!!

Jenny 2