"Exercise-related SCA is almost always a survivable event when you have prompt recognition by witnesses, proper resuscitation, and an AED close by.”
Jonathan Drezner, MD, director of UW Medicine’s Center for Sports Cardiology
A sudden cardiac arrest (SCA) victim's chance of survival is just 9% if the SCA occurs at a fitness center without an AED. If the facility has an AED, the chance of survival jumps to 93%.
Source: https://emergencycare.hsi.com/blog/study-shows-success-of-aeds-in-fitness-centers
Commotio Cordis: “A phenomenon in which a sudden blunt impact to the chest causes sudden cardiac death.”
Source: Nesbitt AD, Cooper PJ, Kohl P. Rediscovering commotio cordis. Lancet. 2001; 357:1195–1197.
As many as 80% of young athletes are completely asymptomatic prior to experiencing SCA.
Source: https://www.cardio.com/blog/youth-athletes-sudden-cardiac-arrest-how-to-protect-young-hearts