Nonventricular arrhythmias as precursors of ventricular fibrillation in patients with out-of-hospital cardiac arrest.

Ventricular tachycardia (VT) and ventricular fibrillation (VF) are the most common arrhythmias documented at the time of resuscitation in survivors of out-of-hospital cardiac arrest unassociated with an acute myocardial infarction. However, 20% and 40% of these patients will not manifest inducible ventricular arrhythmias during subsequent electrophysiologic studies. The optimal management of these patients has been controversial. In a consecutive series of 100 survivors of out-of-hospital cardiac arrest with documented VF, six were identified by either clinical or electrophysiologic data as having a nonventricular arrhythmia as the immediate precursor of VF. Two of these patients had rapid, hypotensive supraventricular arrhythmias induced with programmed cardiac stimulation. In four patients, bradyarrhythmias (sinus arrest two; atrioventricular block two) preceded and caused the episode of VF. Therapy directed at these nonventricular arrhythmias prevented recurrence of cardiac arrest in all patients. In survivors of out-of-hospital cardiac arrest, nonventricular arrhythmias represent a treatable potential etiology that may be overlooked during the patient's evaluation.