Twelve-Month Electrical Lead Performance of His Bundle Pacing Versus Left Bundle Branch Pacing in Older Patients With Bradyarrhythmias: A Retrospective Cohort Study

<title>Abstract</title> <p> <bold>Background</bold> Conduction system pacing is increasingly used to preserve physiological ventricular activation in patients requiring permanent pacing. His bundle pacing provides direct recruitment of the native His–Purkinje system but may be limited by higher or unstable capture thresholds, whereas left bundle branch pacing may offer more favorable electrical parameters. Evidence comparing these strategies in older patients, particularly with systematic frailty assessment and 12-month lead follow-up, remains limited. This study compared procedural characteristics, longitudinal electrical lead performance, and clinical outcomes between His bundle pacing and left bundle branch pacing in older patients with symptomatic bradyarrhythmias. <bold>Methods</bold> We conducted a retrospective cohort study of 167 older patients with symptomatic bradyarrhythmias who underwent conduction system pacing, including 75 treated with His bundle pacing and 92 treated with left bundle branch pacing. Device parameters were assessed at implantation, 6 months, and 12 months. Geriatric-relevant variables, including polypharmacy, multimorbidity, and Clinical Frailty Scale score, were recorded. The primary endpoint was high capture threshold, defined as capture threshold &gt; 1.0 V at 0.4 ms at 12 months. Logistic regression was used to evaluate the association between pacing modality and high capture threshold. <bold>Results</bold> Procedural success was similar between the His bundle pacing and left bundle branch pacing groups [70/75 (93.3%) vs. 85/92 (92.4%); p = 0.815]. Frailty burden was comparable, with a median Clinical Frailty Scale score of 4 (3–5) in both groups. Left bundle branch pacing was associated with a lower implant capture threshold [0.6 (0.45–0.8) vs. 0.8 (0.7–1.0) V; p &lt; 0.001] and higher R-wave amplitude [8.5 (7–11) vs. 5.4 (4–8) mV; p &lt; 0.001], but longer procedure and fluoroscopy times. Capture thresholds remained consistently lower with left bundle branch pacing at 6 months [0.6 (0.5–0.8) vs. 0.9 (0.8–1.2) V; p &lt; 0.001] and 12 months [0.6 (0.5–0.8) vs. 1.0 (0.8–1.3) V; p &lt; 0.001]. High capture threshold at 12 months occurred in 23/72 patients (31.9%) in the His bundle pacing group and 4/88 patients (4.5%) in the left bundle branch pacing group. This association remained significant after adjustment for age, sex, pacing indication, baseline rhythm, lead type, and Clinical Frailty Scale score. Clinical outcomes and overall complications were similar between groups. <bold>Conclusions</bold> In older patients with symptomatic bradyarrhythmias undergoing conduction system pacing, left bundle branch pacing achieved procedural success comparable to His bundle pacing but demonstrated more favorable and stable 12-month electrical lead performance without an increase in overall clinical or device-related complications. These findings support left bundle branch pacing as a practical conduction system pacing strategy in older patients, although longer follow-up is needed to determine whether improved threshold stability translates into better device longevity or clinical outcomes. <bold>Trial registration</bold> Not applicable. </p>