People tend to ask about "saves" from AED's or CPR. What must be remembered is that it is not the ONLY thing that is needed. It is part of the "chain of survival" that includes early 911 access, early defibrillation (AED) early advanced care and then transfer to definitive care.
Though I don't have actual medical studies...personal knowledge aboout AED use (as a medic) I have heard of a few 'saves' but remember that they were all then treated by medics and transferred to doctors. AED saves alone......