BACKGROUND: Right ventricular septal (RVS) pacing is an alternative to right ventricular apical (RVA) pacing, but there is limited information about its influence on long-term left ventricular (LV) synchrony and function. METHODS AND RESULTS: A total of 55 patients undergoing dual-chamber pacemaker implantation with normal QRS duration and preserved LV function at baseline were included in the study. The right ventricular lead was implanted on the septum where it would produce the shortest QRS duration possible in 40 patients and in the apex in 15. The time-to-peak systolic velocity (T(sys)) was measured in 12 segments of the LV wall by tissue Doppler imaging. After a long (approximately 4 years) follow-up period, the LV ejection fraction (LVEF) decreased significantly in patients with RVA pacing but not in those with RVS pacing. Paced QRS duration was significantly shorter during RVS than RVA pacing. T(sys) dispersion among the 12 LV segments was significantly smaller during RVS than RVA pacing. There was a positive correlation between the paced QRS duration and T(sys) dispersion (R=0.65, P<0.0001). The pacing-induced decrease in LVEF was positively correlated with the degree of T(sys) dispersion (R=0.42, P=0.008). CONCLUSIONS: RVS pacing guided by the paced QRS morphology preserves long-term LV function via minimizing LV dyssynchrony.
BACKGROUND: Right ventricular septal (RVS) pacing is an alternative to right ventricular apical (RVA) pacing, but there is limited information about its influence on long-term left ventricular (LV) synchrony and function. METHODS AND RESULTS: A total of 55 patients undergoing dual-chamber pacemaker implantation with normal QRS duration and preserved LV function at baseline were included in the study. The right ventricular lead was implanted on the septum where it would produce the shortest QRS duration possible in 40 patients and in the apex in 15. The time-to-peak systolic velocity (T(sys)) was measured in 12 segments of the LV wall by tissue Doppler imaging. After a long (approximately 4 years) follow-up period, the LV ejection fraction (LVEF) decreased significantly in patients with RVA pacing but not in those with RVS pacing. Paced QRS duration was significantly shorter during RVS than RVA pacing. T(sys) dispersion among the 12 LV segments was significantly smaller during RVS than RVA pacing. There was a positive correlation between the paced QRS duration and T(sys) dispersion (R=0.65, P<0.0001). The pacing-induced decrease in LVEF was positively correlated with the degree of T(sys) dispersion (R=0.42, P=0.008). CONCLUSIONS: RVS pacing guided by the paced QRS morphology preserves long-term LV function via minimizing LV dyssynchrony.