Actually it does require a shock, if the heart has stopped during a heart attack. An attack can disrupt its nerve impulse rhythm, which can lead to atrial fibrillation and subsequent heart failure. A hard shock can sometimes reset the atrial-ventricle nerve impulse synchronization and restore enough of the heart function to survive long enough until emergency care is given. In a hospital, I have actually had atrial fibrillation, and they had to use a controlled shock to reset my heart’s rhythm. It’s called a cardioversion.
O. M. G. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!