To drop like that is considered a cardiac arrest. Not just a regular heart attack. Despite CPR, if there isn’t an AED available nearby, survival rate is usually only about 20%. Cardiac arrest is generally an electrical event, and an electric jolt is needed to shock the heart back into a rhythm.
That is discussed a little in the story about the soccer play who dropped on the pitch from a cardiac arrest
https://www.theguardian.com/football/2012/mar/25/muamba-collapse-minute-by-minute