Clinical outcomes of different right ventricular septal pacing sites in patients with high pacing percentage

Abstract Purpose Although right ventricular (RV) septal pacing is increasingly used as an alternative to apical pacing, the clinical impact of different septal pacing locations remains poorly defined. We evaluated long-term outcomes associated with different RV septal pacing sites in patients with a high ventricular pacing burden. Methods We performed a retrospective observational cohort study including consecutive patients undergoing permanent pacemaker implantation with septal RV lead positioning between October 2022 and February 2025. Patients with sustained ventricular pacing ≥ 40% during follow-up were included. RV lead position was classified as basal, middle, or distal using fluoroscopic and electrocardiographic criteria. The primary endpoint was a composite of emergency department visit for acute heart failure, heart failure hospitalization, or all-cause death. Multivariable Cox regression and inverse probability of treatment weighting (IPTW) analyses were performed. Results Among 322 patients (79.5 ± 9.6 years, 36.7% women), 34 underwent basal, 221 middle, and 67 distal septal pacing. During a median follow-up of 916 days, 77 patients (23.9%) met the primary endpoint. Event rates were significantly lower in the basal and middle groups compared with the distal group (11.8%, 20.8%, and 40.3%, respectively; p = 0.006). After multivariable adjustment, middle septal pacing remained associated with a lower incidence of the primary endpoint compared with distal pacing (HR 0.28, 95% CI 0.13–0.60; p = 0.001). This association remained significant after inverse probability of treatment weighting (IPTW) (HR 0.36, 95% CI 0.17–0.74; p = 0.006). Conclusions Among patients with a high RV pacing burden undergoing septal pacing, middle septal pacing was associated with more favourable long-term clinical outcomes than distal septal pacing. These findings suggest clinically relevant heterogeneity within RV septal pacing locations and highlight the potential importance of precise septal lead positioning. Capsule summary Among patients with a high right ventricular pacing burden, middle septal pacing was associated with more favourable long-term clinical outcomes than distal septal pacing. These findings suggest clinically relevant heterogeneity among septal pacing locations and support careful consideration of septal lead positioning.