[Oliver_W]

I have a heart condition called Brugada Syndrome. If you die from it, it's completely undetectable, so a postmortem would show what it did to the heart, but not why it happened, if that makes sense. It's only visible when a certain test is carried out, and that would only be done if someone survived a heart attack and no other disease was known of, and then to the person's relatives.

When athletes etc collapse and die for no apparent reason, they probably had this too!