But who calls an ambulance? Now that's an opportunity for a wearable device.
Of course it gave you a warning buzz first and had a "cancel" button so you could avoid being shocked if you were actually still OK. And it wouldn't shock you, AFAIK, unless you were in a "shockable rhythm"[2].
Anyway, it's still a bit big, bulky and uncomfortable and I doubt you'll see millions of people wearing something like this anytime soon, but as things get lighter and cheaper and better, it might just become mainstream.
[1]: https://en.wikipedia.org/wiki/Implantable_cardioverter-defib...
My doctors initially suggested that I might need a implantable defibrillator if my EF didn't recover sufficiently, but it turns out that by about 3 weeks after, my EF was back close to normal, so no defibrillator required. Now I'm hoping I can talk my cardiologist into taking me off of Metoprolol at some point, since I do some competitive endurance athletics and that stuff supposedly hurts your performance. And from what I've been reading, some newer research suggests that there's no real benefit to continuing to take it more than a year after an MI.