An estimated 494,382 Americans died of coronary heart disease (ICD-10 codes I20-I25) in 2003. Closer analysis of these mortality data suggests that approximately 330,000 deaths occurred out-of-hospital or shortly after arrival at hospital. Although not a perfect measure of the number of nontraumatic out-of-hospital cardiac arrests, this latter statistic captures the scope of the problem in the United States.

Treatment of cardiac arrest victims has evolved a great deal over the last 47 years. Before that, resuscitation using advanced techniques was the domain of anesthesiologists and was performed only in hospitals. Survival from cardiac arrest outside of that environment was unlikely. Today, well-trained emergency medical service (EMS) personnel routinely attempt out-of-hospital resuscitations and, in many cases, arrive at the scene to find a bystander performing CPR, occasionally also using an automated external defibrillator (AED). Although the overall survival rate for out-of-hospital cardiac arrest (all presenting rhythms) in the United States remains low at approximately 6.4% of the combined efforts of bystanders from the general public agencies, EMS systems, and other public agencies. However, survival rates in some cities of the United States have reached 30% to 40% among patients who presented with ventricular fibrillation as the initial arrhythmia.