My wife and I both have Apple Watches as we have IPhones. They work together well. 
We both have had heart issues, she AFIB and I SVT. We both have used the heart features to show the doctor what is happening as the phone retains the information. 

I had an ablation a couple of years ago that totally stopped my SVT from happening.  My wife has one scheduled for December to hopefully stop the AFIB from happening. 

Chuck