Adverse effect of right ventricular pacing prevented by biventricular pacing during long-term follow-up: a randomized comparison

To investigate whether biventricular (BIV) pacing preserves left ventricular ejection fraction (LVEF) and reduces LV dyssynchrony when compared with standard dual-chamber right ventricular (RV) pacing in consecutive patients with high-grade atrioventricular block during 3 years of pacing. Fifty patients were randomized to RV pacing or BIV pacing. LVEF was measured using three-dimensional echocardio- graphy. Tissue Doppler imaging was used to quantify LV dyssynchrony in terms of the standard deviation of the time- to-peak velocity (Ts-SD). LVEF differed significantly between the two groups during 3 years of pacing (ANOVA: P ¼ 0.003). LVEF in the RV group decreased from 59+5% at baseline to 53+11% (P ¼ 0.01), while LVEF remained unchanged in the BIV group (57+7% at baseline vs. 58+10% (P ¼ 0.40). After 3 years of follow-up, we observed no difference in LV dyssynchrony, LV remodelling or measurements of clinical heart failure (N-terminal pro-brain natriuretic peptide, walking test, and New York Heart Association functional class) between the two groups. However, in the RV group, but not in the BIV group, dyssynchrony increased significantly (P ¼ 0.005) during follow-up. Furthermore, adverse LV remodelling was observed in the RV group with increased systolic volume and thinning of the LV septum.