For a patient in cardiac arrest with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), what intervention provides the best chance of survival?

For cardiac arrest due to ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) — both shockable rhythms — early defibrillation is the most critical intervention. The probability of successful defibrillation decreases approximately 10% per minute without treatment. Dental offices should have an AED available and staff trained in its use. CPR maintains minimal circulation until defibrillation can be performed, but cannot restore a normal rhythm in VF/pVT. The Chain of Survival includes: early recognition and calling EMS, early CPR, early defibrillation, advanced care, and post-cardiac arrest care.