Baseline characteristics
Permanent HBP or LBBP was successful in 34 of 36 patients. The average LVEF value was dramatically low (33.76±7.54% vs. 51.77±8.19%) after right ventricular septal pacing for 79.18 (19-321) months, and 12 patients showed elective replacement indicators (ERIs) at the latest programming before the upgrade procedure. Permanent HBP upgrades were successful in 29 of 34 patients, and LBBP upgrades were successful in 5 patients. Two patients failed in upgrades, and one of them died for heart failure after 12 months follow-up. Eight patients were permanent AF. Nine patients (26.47%) were infranodal block. The devices of CRT were implanted in 13 (38.24%) patients. Dual-chamber pacemakers were implanted in 20 patients (58.82%), and implantable cardioverter defibrillator (ICD) were implanted in one patient (2.94%). The baseline characteristics were shown in Table 1.