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

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 greater than or equal to 200 ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, crossover 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 signifi-cant difference. However, in the patients with effective therapy the mean walked distance increased by 9.3% with biventricular pacing (374 +/- 108 vs 342 +/- 103 in 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 (P<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. (C) 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.