Comparing Conduction System Pacing to Biventricular Upgrade in Pacemaker-Induced Cardiomyopathy: A Retrospective Observational Study.

Background/Objectives: Pacemaker-induced cardiomyopathy (PICM) develops in up to 30% of patients with chronic right ventricular pacing. While biventricular (BIV) upgrade is the conventional strategy, conduction system pacing (CSP) offers a physiologic alternative recently endorsed by the 2025 ESC/EHRA Consensus Statement. However, comparative evidence in PICM is limited. Therefore, we aimed to compare outcomes of PICM patients undergoing CSP versus BIV upgrade. Methods: This retrospective analysis included consecutive PICM patients who were upgraded to CSP or BIV between 2022 and 2024 at a single, experienced center. Follow-up averaged >19 months. Clinical outcomes, lead performance, echocardiographic parameters, complications, and quality of life (QoL) were evaluated. Results: Sixty-three patients were included (CSP: 26; BIV: 37). Mean age and sex distribution were similar; both groups had wide paced QRS complexes and a high ventricular pacing burden. Baseline left ventricular ejection fraction (LVEF) was lower in BIV patients (29 ± 7% vs. 35 ± 6%, p = 0.01). Procedure duration was comparable, but fluoroscopy was shorter with CSP. QRS duration narrowed significantly in both groups (CSP: 163 ± 28→132 ± 12 ms; BIV: 171 ± 23→140 ± 18 ms; both p < 0.05). During follow-up, LVEF improved (CSP: 41 ± 8%; p = 0.008; BIV: 39 ± 8%, p = 0.0001), as did NYHA class, with no significant intergroup differences. The rates of heart failure hospitalization, all-cause mortality, and QoL were similar. Notably, 34.6% of CSP patients retained their existing generator, suggesting procedural and economic benefits. Conclusions: CSP is a feasible and potentially cost-efficient alternative to BIV upgrade in PICM, with comparable improvements in ventricular function, symptoms, and clinical outcomes. Larger prospective trials are warranted.