The study compares the effectiveness of two fully approved shock waveforms (monophasic and biphasic shock) commonly used to defibrillate (shock) patients with out-of-hospital cardiac arrest due to a highly lethal rhythm problem (ventricular fibrillation). The purpose of the study (hypothesis) is to determine if one waveform results in improved resuscitation, admission alive to hospital, and discharge alive from hospital compared with the other.

The trial is designed to determine whether two fully-FDA-approved, commercially available transthoracic defibrillation shock waveforms at comparable energies result in improved patient outcome following out-of-hospital cardiac arrest due to ventricular fibrillation. Eligible subjects include all adults with nontraumatic out-of-hospital cardiac arrest due to ventricular fibrillation. Subjects in cardiac arrest will be randomly allocated to receive one of two types of defibrillation shocks (monophasic or biphasic waveform) during their resuscitation, which will in addition include all other standard treatments. The primary endpoint is admission alive to hospital. Secondary endpoints include rhythm after defibrillation shock, return of spontaneous circulation, and hospital discharge rates.

Inclusion Criteria:

• Adult victims of nontraumatic out-of-hospital cardiac arrest due to ventricular fibrillation

Exclusion Criteria:

• Children
• Trauma