I used to work in collegiate sports. At any given time I would be on 20-25 campuses every season.
An athlete dropping during or after a game from some undiagnosed heart disease was not “common.” But…it happened three times in my 15 year career, either at one of my schools or in their conferences.
The two most common sports I’d seen are lacrosse and basketball.
It is a lot less common now, because pediatricians insist on heart screens for athletes. Ours would not sign a physical without one.