Po-03-019 echocardiographic outcomes of his bundle and left bundle branch area pacing: a single center experience

Traditional right ventricular apical pacing is associated with risk of pacing induced cardiomyopathy (PICM), atrial fibrillation, and heart failure. Conduction system pacing (CSP) via the His or left bundle branch area (HBP, LBBAP) may mitigate or even prevent the development of these complications. To evaluate the effects of CSP on cardiac function as measured by standard 2D-echocardiography. Consecutive patients undergoing HBP or LBBAP implantation between Feb 2014 and July 2022 at Virginia Commonwealth University were analyzed. Ejection fraction (EF), left ventricular diastolic dimension (LVIDd), left ventricular systolic dimension (LVIDs), tricuspid regurgitation severity, and mitral regurgitation severity were compared pre- and post- CSP. Only patients with echo data at 90 days or greater from time of implant were included. A total of 340 patients with CSP had echocardiographic data available. Mean clinical follow up time was 810 days from implant, and median time until post-implant EF was 483 days (IQR 324-763). 77 had reduced EF (<50%) at baseline. Pacing burden exceeded 20% across the cohort. The mean pre- and post- CSP implantation EF in the overall group was 53.8% ±10.9% vs 54.7% ±9.1% (p=0.08). Mean pre- and post- CSP implant LVIDd was 4.59±0.73cm vs 4.37 ±0.72 cm (p<0.001). Mean pre- and post- CSP implant LVIDs was 3.23± 0.79cm vs 3.05± 0.76cm (p<0.001). TR and MR severity were unchanged after pacemaker implantation. In the subset of patients with reduced EF, mean pre-implant EF was 37% ±9.4% and post-implant EF was 47% ±11.6% (p<0.001). Mean pre-implant LVIDd was 5.02cm ±0.86cm and post-implant LVIDd was 4.60cm ±0.75cm (p<0.001). Mean pre-implant LVIDs was 4.05cm ±1.0cm and post-implant this dropped to 3.44cm ±0.96 (p<0.001). CSP via HBP or LBBAP is not associated with PICM in patients requiring high ventricular pacing burdens. In patients with a reduced EF, it may significantly improve systolic function along with positive structural remodeling.