I can imagine there being a small positive correlation between wearing an Apple watch and having heart attacks, somewhat like the plane armor story from WWII (https://en.wikipedia.org/wiki/Survivorship_bias#In_the_milit...).

Without the Apple watch monitoring your heart rate: you don't see the warning signs early enough and have a fatal heart attack, once.

With the Apple watch: you get alerted earlier, get to hospital and survive your heart attack. So you can go on to have another, and another, and another. All contributing to the "heart attacks while wearing Apple watches" statistic ;)

FWIW Apple watches are 100% not recommended as a way of telling if you're having a heart attack: https://support.apple.com/en-us/HT208931

They're also not testing for the more dangerous ventricular fibrillation.

I believe elevated anxiety for health isn't good for your health in general, especially for your heart.