no idea if that stat is correct but you last comment is very true. There is no telling when someone will have a cardiac event occur. everyone likes to blame diving but its just by chance that it happens to the diver the exact moment they are under the water ...Many heart attacks happen first thing in the morning because as we wake up our biological oxygen demand increases before our heart rate does. If the heart is already compromised this can push it into an arrhythmia that kills the patient.
Fact is, everyone dies. In many cases, what they are doing when they die has no bearing on the eventual outcome.