He may have decided there wasn’t much he could do about his heart condition and would live with it, or not, as the case may be. Maybe he just refused to change his life, doing what he was doing, to play it safe to accommodate a heart condition.
Whatever he choose it certainly appears this very well could have been a heart attack. Still at 43 yrs. old it’s such a loss.
I have a friend whose male members all must watch their hearts closely. Already the father and one son have died in their sleep from heart attacks.