I'm rolling my eyes at the potential for an unhealthy positive feedback loop.
Your watch notifies you of an irregular heart rhythm, which in turn increases the irregularity of your already (supposedly) irregular heart rhythm; so your watch notifies you again, which proceeds to up your heart rate even more; thus your watch notifies you yet again...
And the next week we read in the papers:
"Apple Watch Kills Man. Autopsy Reveals Perfectly Healthy Heart."
Unlikely, I know.

I'm just trying to illustrate the fact that, before we fall in love with supposedly helpful technologies, we ought to consider all their potential effects - both good, and bad.