A prospective randomized study of the clinical efficacy and safety of transvenous cardioversion for termination of ventricular tachycardia

Abstract

The clinical efficacy and safety of transvenous cardioversion for termination of sustained ventricular tachycardia (VT) were examined by a prospective randomized study design in 22 patients (19 men, 3 women; mean age 64 ± 9 years) with organic heart disease and sustained VT. Patients were randomly assigned to undergo an incremental low-energy protocol from 0.03 to 2.2 J (group A, 11 patients) or an incremental high-energy protocol from 0.5 to 10.0 J (group B, 11 patients). Transvenous cardioversion was performed during electrophysiologic studies in the control (drug-free) state and during serial antiarrhythmic drug testing in all patients. Both groups were comparable for demographic, disease and functional status, and electrophysiologic parameters. A total of 77 episodes of VT (group A, 45; group B, 32) were analyzed. The overall efficacy of transvenous cardioversion for termination of VT was 62% (group A 56% vs group B 72%; p < .01). Antiarrhythmic drug therapy did not significantly enhance efficacy of transvenous cardioversion (control 59% vs drug 65%; p < .2). Stepwise discriminant analysis correlated successful transvenous cardioversion with longer VT cycle length (p < .0005), higher energy (p < .025), lower energy waveform tilt (p < .025), shorter time to initial cardioversion attempt (p < .025), and shorter QRS duration in sinus rhythm (p < .05). Acceleration of VT was frequent (8% incidence per delivered shock). Thirty-one percent of all incremental shock protocols were terminated because of this complication. After cardioversion, transient arrhythmias were common (bradyarrhythmias 23%, supraventricular tachyarrhythmias 12%). Displacement of electrode catheters after transvenous cardioversion was uncommon (3%). We conclude that transvenous cardioversion has limited efficacy for termination of VT in unselected patients. The clinical efficacy of the technique can be enhanced by careful patient selection with respect to influencing variables. Acceleration of VT further limits efficacy and requires the availability of defibrillation capabilities.