Aims: 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.
Methods and results: Fifty patients were randomized to RV pacing or BIV pacing. LVEF was measured using three-dimensional echocardiography. 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=0.003). LVEF in the RV group decreased from 59±5% at baseline to 53±11% (P=0.01), while LVEF remained unchanged in the BIV group (57±7% at baseline vs. 58±10% (P=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=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.
Conclusion: BIV pacing preserves LVEF and minimizes LV dyssynchrony during long-term follow-up. Adverse remodelling observed during 3 years of RV pacing was prevented by BIV pacing. However, the adverse impact of RV pacing on LV function was not reflected in measures of clinical heart failure.
Clinical trial registration: www.clinicaltrials.gov (identification number: NCT00228241).