Depends on how long it took for Mitchy to get defibbed... assuming appropriate CPR until the AED is ready, first few minutes could be around 2/3 chance of survival, anything significantly more than 10 minutes we're looking at less than 1/4 chance.

(Sounds like mitch was unconscious from a fall and not a cardiac arrest, reports were that CPR was administered but was he breathing at some point? Mysteries still abound)