Atrial fibrillation and flutter with left bundle branch block aberration referred as ventricular tachycardia.

Five patients were referred for electrophysiologic evaluation of nonsustained or sustained ventricular tachycardia. In each patient, the clinical rhythm disturbance was reproduced and identified as atrial fibrillation or flutter with left bundle branch block aberrancy. All five patients demonstrated enhanced or accelerated atrioventricular conduction through the normal atrioventricular nodal-His Purkinje pathway. This rapid conduction created an electrophysiologic substrate suitable to the preferential development of this less common form of aberration. Four of five patients responded well (ventricular rate control or reversion to sinus rhythm) to verapamil therapy. Electrocardiographic criteria for differentiating supraventricular tachycardia with aberration from ventricular tachycardia exist. Nevertheless, misdiagnosis of wide complex tachycardia remains common. Electrophysiologic testing plays an important role in correctly identifying these rhythms, assessing long-term prognosis, and choosing effective therapy.