MODE OF ONSET OF MALIGNANT VENTRICULAR ARRHYTHMIAS IN IDIOPATHIC VENTRICULAR-FIBRILLATION

Mode of Onset of Idiopathic VF. Introduction: The mode of onset of mal ignant ventricular arrhythmias (ventricular tachycardia [VT] or ventri cular fibrillation [VF]) has been well described in patients with orga nic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out-of-hospital V F who have no evidence of organic heart disease or identifiable etiolo gy. Methods and Results: We reviewed the ECGs of all our patients with idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VF episodes in 9 patients (6 men and 3 women; age 41 +/- 16 years). In all instances, spontaneous VF followed a rapid p olymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 +/- 52 msec and a prematurity index of 0.4 /- 0.07. These PVCs occurred within 40 msec of the peak of the precedi ng T wave. Pause-dependent arrhythmias were never observed. Conclusion : Cardiac arrest among patients with idiopathic VF has a very distinct ive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.