Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation

Abstract

Background: One third of chronic heart failure patients have major intraventricular conduction and uncoordinated ventricular contraction. Non-controlled studies suggest that biventricular pacing may improve haemodynamics and well-being by reducing ventricular asynchrony. The aim of this trial was to assess the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation. Methods: Fifty nine NYHA class III patients with left ventricular systolic dysfunction, chronic atrial fibrillation, slow ventricular rate necessitating permanent ventricular pacing, and a wide QRS complex (paced width ≥200 ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, cross-over study compared the patients' parameters, as monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. The primary end-point was the 6-min walked distance, secondary endpoints were peak oxygen uptake, quality-of-life, hospitalizations, patients' preferred study period and mortality. Results: Because of a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, we did not observe a significant difference. However, in the patients with effective therapy the mean walked distance increased by 9·3% with biventricular pacing (374 ± 108 vs 342 ± 103 m in univentricular; P=0·05). Peak oxygen uptake increased by 13% (P=0·04). Hospitalizations decreased by 70% and 85% of the patients preferred the biventricular pacing period (Pe<0·001). Conclusion: As compared with conventional VVIR pacing, effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes. Further randomized controlled studies are required to definitively validate this therapy in such patients. © 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.