Biventricular pacing in patients with congestive heart failure: Two prospective randomized Trials

Epidemiologic studies suggest that 20-30% of patients diagnosed with sympto matic congestive heart failure (CHF) have intraventricular conduction disor ders characterized by a discoordinate contraction pattern and wide QRS. Biv entricular pacing is an emerging therapy allowing simultaneous electrical s timulation of the right and left ventricles with the use of an implantable pacing system. The aim of this article is ta describe 2 prospective randomi zed multicenter trials examining the effects of biventricular pacing on fun ctional capacity, quality of life, and hemodynamic states in patients with dilated cardiomyopathy and intraventricular delay. The VIGOR CHF Trial is d esigned to assess functional and symptomatic improvement in heart failure p atients with biventricular pacing and without a concomitant indication for conventional bradycardia pacemaker therapy. To assess for potential placebo effects, patients are randomized to receive either biventricular pacemaker therapy or no pacing therapy for the first 6 weeks, after which both group s receive pacing therapy. The VENTAK CHF trial uses an implantable cardiove rter defibrillator system (ICD) designed to provide chronic biventricular p acing therapy in addition to treating ventricular tachyarrhythmias. All pat ients receive conventional ICD and CHF therapy throughout the study and are randomized in a a-period crossover design to receive either no pacing or b iventricular pacing for 3-month intervals. Patient enrollment in both studi es is ongoing, with a closed analysis. The unique designs of these trials p rovide the opportunity to study this therapy in high-risk patients who have been optimally treated for heart failure. (C) 1999 by Excerpta Medica, Inc .