Mitigation of pacing‐induced cardiomyopathy with superficial right ventricular mid‐septal pacing: A long‐term retrospective comparison with apical pacing

INTRODUCTION: It remains unclear if pacing induced cardiomyopathy (PICM) may be minimized by standard pacing of the right ventricle (RV) at sites other than the RV apex. The purpose of this study is to compare the relative frequency of PICM in a population of patients paced at either the superficial RV mid septum (RVMS) or RV apex (RVA), and other outcomes that may differ between these sites. METHODS AND RESULTS: A retrospective evaluation was performed on all patients undergoing pacemaker implantation between 2011 and 2022. Potential study patients were those with Medtronic 3830 superficial RVMS leads placed with septal specific guidance catheters, and any with RVA leads. Patients were included if they had ≥20% RV pacing, available baseline and follow-up measurements of left ventricular ejection fraction (LVEF) at least 6 months postimplantation, and a baseline LVEF ≥50%. PICM was defined as a decline in the LVEF of at least 10%, resulting in LVEF <50%. Patients were excluded for Biventricular devices, and for alternative causes of cardiomyopathy. The study criteria were met in 324 patients, with 220 RVMS and 104 RVA paced patients. PICM occurred in 4.5% of RVMS patients, and 22.1% of RVA patients (p < .001). Additional differences were demonstrated in paced QRS duration (144 ± 15.5 ms in RVMS, 166 ± 19.4 ms in RVA; p < .001); QRS axis (2.3 ± 64.9 in RVMS, -65.2 ± 49.5 in RVA; p < .001), and various qualitative QRS morphologic characteristics. CONCLUSION: Patients with normal LVEF experienced significantly less PICM with superficial RVMS pacing performed via septal specific guidance catheters than similar counterparts with RVA pacing. Narrower paced QRS duration and less left axis deviation was also demonstrated.