Hence the 'might'. An AED may be able to restart a heart in ventricular fibrillation or ventricular tachycardia (I suppose we can quibble over what 'restart' me

Hence the 'might'. An AED may be able to restart a heart in ventricular fibrillation or ventricular tachycardia (I suppose we can quibble over what 'restart' means). CPR alone never restarts a heart (ok... not 'never', but it's uncommon enough (in adults) that it's not worth fighting over).