Is Right Ventricular Outflow Tract Pacing Superior to Right Ventricular Apex Pacing in Patients with Normal Cardiac Function?

Background: Whether right ventricular outflow tract (RVOT) pacing is superior to right ventricular apex (RVA) pacing in terms of ventricular synchrony, cardiac function, and remodeling in patients with normal cardiac function is still unknown. Hypothesis: Right ventricular outflow tract pacing is superior to RVA pacing in patients with normal cardiac function. Methods: A total of 96 consecutive patients with high or third-degree atrial ventricular block were enrolled and randomized into 2 groups: RVOT pacing group (n = 48) and RVA pacing group (n = 48). Tissue Doppler imaging (TDI) and 2D echocardiography were performed to study left ventricular (LV) systolic and diastolic synchrony, LV volumes, and function. Results: There were no significant differences in baseline characteristics between the 2 groups. Leftventricular systolic asynchrony is more severe in the RVA pacing group than in the RVOT pacing group (P < 0.05), while diastolic synchrony is not significantly (NS) different between the 2 groups after pacing. There were no significant differences with respect to the mean myocardial systolic (Sm) and early diastolic velocities (Em), LV ejection fraction, LV end-diastolic and systolic volume in the 2 groups at 12 months of follow-up (all NS). Conclusions: Although RVOT pacing caused more synchronous LV contraction compared with RVA pacing, it had no benefit over RVA pacing in aspect of preventing cardiac remodeling and preserving LV systolic function after 12 months of pacing in patients with normal cardiac function.