From a nurse's perspective, I do not think it is not helpful to speculate what happened here. It is very sad and unfortunate; the man was not very old and probably didn't think, "Hey, I might die today." Whether or not he made a diving error or had a MI, who knows. It could just as well have happened in the bathtub or on the lawnmower or in the car for all we know. But this should just make all of us divers realize that it is our own responsibilities to know our health limitations, to know what is going on with our bodies physically (whether we are having symptoms of illness or not), and to know the risks we take that are inherent to diving when we're out in the middle of nowhere, maybe 100ft down, and something goes wrong. We are not guaranteed another day here on earth. Makes you kind of want to schedule a routine physical, doesn't it? I am very sorry for this family. This is a tragedy.