Do anyone know how a hit in the chest can make a hearth stop?
It can happen... every once in awhile you hear about a youth or high-school baseball player dying after being hit in the chest.
However, there's a heart condition that can cause sudden death in teenage/young adult athletes... I can't think of what it's called, but autopsies on young athletes who die suddenly while exercising often find evidence of it. Maybe Cherepanov had it and the fact that he collapsed after a hit was coincidence. I don't know how advanced cardiac science in Russia is, or how commonly autopsies are done there, so we may never know.