I saw JR said something on Twitter about blocked arteries, which will get sorted out (I think surgery for that is non-invasive too - not 100% on that though)
Hopefully the actual heart attack caused him no permanent damage. That is the big worry now IMO.
Yeah, my dad has had several such surgery's. Worst case it's a bypass, where they take an artery out of your leg (or arm) and put it instead of the normal artery. More like they can either do a non-invasive procedure called, actually I don't know the english term, but it's basically where they go into the artery and pump up a balloon to remove the blockage. If that doesn't work they put in a ring that opens up the artery perminantly.