Could be a few things. Genetic issue with skyhigh cholestrol he wasnt aware of. Could've been clot in leg that went to heart causing the MI. And last but not least couldve been any number of drugs rx legal or otherwise. Probably come out soon enough especially if he goes donkdown they'll end up releasing a cause. The biggest issue is he could have massive brain damage from lack of O2 and still ultimately die or end up a veg for life.