Is immediate defibrillation of v fib typically successful with at least restoring a normal sinus rhythm?

Usually: Time is the key when it comes to successful defibrillation: literally each minute counts. Defibrillation success rates decrease about 5%-10% for each MINUTE after the onset of VF. In strictly monitored settings where defibrillation was performed most promptly, success rates of 85% have been reported. Having AEDs readily accessible and citizens trained in the use of AEDs will save lives.