Every year out-of-hospital ventricular fibrillation cardiac arrests kill hundreds of thousands of people worldwide, often striking those without obvious high-risk conditions or symptoms.1 The fundamental strategy to improve survival is to reduce the time interval from collapse to defibrillation, as the likelihood of survival decreases on average about 5–10% for each minute that elapses without defibrillator treatment. The traditional deployment model is to equip specific emergency medical services (EMS) professionals, who are activated to respond with a defibrillator and deliver the potential life-saving shock. In most communities, the average interval from the emergency call to EMS defibrillator care exceeds 8 min, an interval that results in less than a quarter of patients surviving. In many communities the survival rate is in the single digits. Early bystander cardiopulmonary resuscitation, expert EMS care and comprehensive hospital management have an integral life-saving role, but the effectiveness of these links is undermined by delays in defibrillation.

Thus the development of the automated external defibrillator (AED)—which can assess the cardiac rhythm and correctly deliver a shock to the fibrillating heart—holds great promise. An AED enables almost anyone to save a life so long as the rescuer has ready access to an AED. The approach was rigorously evaluated in the public setting more than a decade ago, with results indicating that public access defibrillation (PAD) can double survival.2 A subsequent trial in the home setting did not demonstrate survival benefit, in part because the event rate was substantially lower than anticipated, making robust comparative evaluation challenging.3 Nevertheless, when the AED was …