ELECTROCARDIOGRAPHIC IDENTIFICATION OF ABNORMAL VENTRICULAR DEPOLARIZATION AND REPOLARIZATION IN PATIENTS WITH IDIOPATHIC VENTRICULAR-FIBRILLATION

Objectives. We sought to gain more insight into the arrhythmogenic eti ology of idiopathic ventricular fibrillation (VF) by assessing ventric ular depolarization and repolarization properties by means of various electrocardiographic (ECG) techniques. Background. Idiopathic VF occur s in the absence of demonstrable structural heart disease. Abnormaliti es in ventricular depolarization or repolarization have been related t o increased vulnerability to VF in various cardiac disorders and are p ossibly also present in patients with idiopathic VF. Methods. In 17 pa tients with a first episode of idiopathic VF, 62-lead body surface QRS T integral maps, QT dispersion on the 12-lead ECG and XYZ lead signal- averaged ECGs were computed, Results. All subjects of a healthy contro l group had a normal dipolar QRST integral map. In patients with idiop athic VF, either a normal dipolar map (29%), a dipolar map with an abn ormally large negative area on the right side of the thorax (24%) or a nondipolar map (47%) were recorded. Only four patients (24%) had incr eased QT dispersion on the 12-lead ECG and late potentials could be re corded in 6 (38%) of 16 patients. During a median follow-up duration o f 56 months (range 9 to 136), a recurrent arrhythmic event occurred in 7 patients (41%), all of whom had an abnormal QRST integral map. Five of these patients had late potentials, and three showed increased QT dispersion on the 12 lead ECG. Conclusions. In patients with idiopathi c VF, ventricular areas of slow conduction, regionally delayed repolar ization or dispersion in repolarization can be identified. Therefore, various electrophysiologic conditions, alone or in combination, may be responsible for the occurrence of idiopathic VF. Body surface QRST in tegral mapping may be a promising method to identify those patients wh o do not show a recurrent episode of VF. (C) 1998 by the American Coll ege of Cardiology.