>But this is exactly what I'm taling about; I'm hoping for a time when medical science has progressed to a point where these issues are very well understood, and seemingly random cardiac arrests like this can be preempted and prevented. I believe it's possible.

This is simply a discussion of semantics, and I feel kind of silly for arguing it in the first place. You're absolutely correct that most of the 'random' sudden cardiac deaths that occur are in fact related to a previously unknown preexisting condition. Wolff-Parkinson-White, congenital long Q-T, and a variety of cardiomyopathies (most of them congenital as well) can easily predispose someone to dropping dead.