Biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients

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.1This single-blind, randomized, controlled, crossover study assessed the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation. 1Fifty 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 ≥2000ms), were implanted with transvenous biventricular-VVIR pacemakers. 1The study patients' parameters were monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. 1The primary end-point was the 6-min walked distance and the secondary end-points were peak oxygen uptake, quality-of-life, hospitalizations, patients' preferred study period and mortality. 1The results showed a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, no significant difference was observed. "However, in the patients with effective therapy the mean walked distance increased by 9?3% with biventricular pacing (374±108 vs 342±1030m 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 (P1The authors conclude " 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."1Reference...