Similar long-term benefits conferred by apical versus mid-septal implantation of the right ventricular lead in recipients of cardiac resynchronization therapy systems.

INTRODUCTION: The benefits conferred by cardiac resynchronization therapy (CRT) are markedly influenced by the left ventricular (LV) lead placement. Little is known regarding the optimal right ventricular (RV) stimulation site.

STUDY OBJECTIVE: To compare the long-term outcomes of CRT in patients with RV leads placed in the mid-septal region versus the apex.

METHODS AND RESULTS: This nonrandomized, observational study included 117 patients with standard indications for CRT. The LV lead was implanted on the postero-lateral or lateral LV wall, while the RV lead was implanted at the apex (n = 82) or in the mid-septum (n = 35). Both groups were similar with respect to baseline clinical, demographic, and echocardiographic characteristics. After 12 months of CRT, the rates of clinical response to CRT were similar in both groups (63% vs. 66%), and similar degrees of reverse LV remodeling and LV resynchronization were observed on echocardiography and color tissue Doppler imaging. A > or =30% relative increase in LV ejection fraction (EF) occurred in 76% of patients in the RV apex group, versus 49% of patients in the RV mid-septum group (P = 0.05). A > or =45% left ventricular ejection fraction (LVEF) was measured at 12 months in 40% of patients in the RV apex group, versus 31% in the RV mid-septum group (ns).

CONCLUSIONS: RV mid-septal stimulation was not associated with a higher rate of response to CRT or greater improvement in LV function compared to RV apical stimulation.