3.1 Patient and pacing characteristics
A total of 1132 underwent PM implantation during the study period. Of these, 134 patients with pre-implantation LVEF < 50.0% were excluded. Another 249 (24.9 %) patients were lost to follow-up and were excluded. Hence, a total of 749 patients were included in the final analysis.
The mean age of the cohort was 59.2 ± 14.1 years and 31.6% were female. The most common indication for pacing was degenerative high-grade AV block seen in 74.37% of the study population. The other causes included sick sinus syndrome, carotid sinus hypersensitivity and syncope of unknown origin. About half of the patients had baseline bundle branch block or intraventricular conduction defect (IVCD). Mean pre-implantation LVEF was 57.3 ± 3.3 %. The majority of the patients (71.2 %) received a dual-chamber pacemaker and most (69.6 %) had an RV lead placed in a non-apical location. The median RV pacing burden was 81% (IQR 15-99%). Other patient, procedural, and pacing characteristics are summarized in Table 1.