Outcomes of Septal Versus Non‐Septal Right Ventricular Pacemaker Leads as Adjudicated by CT Imaging

BACKGROUND: Right ventricular (RV) apical pacing is associated with pacing induced cardiomyopathy. RV septal pacing has been proposed as a more physiological alternative, yet prior studies have yielded conflicting results. Cardiac computed tomography (CT) provides superior anatomical adjudication of lead position. We sought to evaluate whether CT-confirmed septal lead placement is associated with improved clinical outcomes compared with non-septal pacing. METHODS: We conducted a retrospective cohort study of 657 patients who underwent PPM implantation at the University of Pittsburgh Medical Center with subsequent chest CT imaging. The lead position was adjudicated as septal or non-septal. The primary outcome was a composite of heart failure hospitalization, atrial fibrillation admission, and/or all-cause mortality. Secondary outcomes included longitudinal changes in left ventricular ejection fraction (LVEF), and 12-month admission burden. RESULTS: Data from 657 patients were analyzed. Mean age was 73.9 ± 11.9 years, 50.5% were female, and mean baseline LVEF was 54.9 ± 7.1%. 150 had septal leads (22.8%), and 507 (77.2%) had non-septal leads. Over a median follow-up of 5.3 years (IQR 3.1-8.2), the composite endpoint occurred in 70.2% of patients, with incidence in the septal group (62.7%) and non-septal (72.4%, p = 0.21). In multivariable-adjusted multivariable adjusted models, septal versus non-septal pacing was not significantly associated with the composite outcome (HR = 1.00, 95% CI: 0.80-1.25, p = 0.996). LVEF declined in the non-septal group (54.0 ± 9.2% to 50.5 ± 11.4%, p < 0.001) but remained stable in the septal group (55.0 ± 6.6% to 54.9 ± 7.0%, p = 0.43). No significant differences were observed in the 12-month admission rates by lead position. CONCLUSIONS: Septal pacing was associated with preservation of left ventricular function compared to non-septal pacing, although this advantage did not translate to improved clinical outcomes. Septal pacing may help to reduce pacing-induced ventricular dysfunction when conduction system pacing is not feasible.