AIM   To investigate the effect of left bundle branch area pacing (LBBAP) on the incidence of new onset atrial fibrillation (AF) and on cardiac functions in patients with medium or long-term high proportion of ventricular pacing.

  METHODS  Patients with atrioventricular block and indication for pacing were recruited and randomly assigned to LBBAP high ventricular pacing group (LBBAP-high Group), right ventricular septal pacing (RVSP) high ventricular pacing group (RVSP-high group) or RVSP low ventricular pacing group (RVSP-low group). Patients were followed up at 3 months, 6 months and every 6 months after the operations. The atrial high rate events (AHREs) documented by pacemaker, with frequency greater than 180 beats per minute, duration greater than 1 minute and automatic mode conversion (AMS) occurrence were recorded and deemed as AF events. AHREs, AF events documented by Holter monitor, echocardiography parameters, and NT-proBNP levels at each follow-up point were recorded. Kaplan-meier method was applied to draw the time curve of AF in each group and COX proportional hazard model was applied to analyze the correlation of multiple factors with new-onset AF.

  RESULTS  Compared with LBBAP high group, QRS width of pacing increased in RVSP low group (P<0.01) and RVSP high group (P<0.01). The incidence of new atrial fibrillation increased with time. A total of 59 cases (57%) of atrial fibrillation events were recorded in the three groups, including 15 cases (44%) in LBBAP high group, 11 cases (38%) in RVSP low group, and 33 cases (82%) in RVSP high group. The rate of new atrial fibrillation in RVSP high group was significantly higher than that in LBBAP high group and RVSP low group (P<0.01). The false discovery rate (FDR) method was used to compare two groups: the sinus rhythm retention rate between LBBAP high group and RVSP high group was statistically significant (P<0.01); There was significant difference in sinus rhythm retention rate between RVSP high group and RVSP low group (P<0.01). There was no significant difference in sinus rhythm retention between LBBAP high group and RVSP low group. COX single factor regression analysis showed that right ventricular septal pacing with high pacing ratio (HR=3.004; 95% CI: 1.615～5.586; P<0.01), low ejection fraction (HR=1.029; 95% CI: 1.004～1.054; P<0.05) and hypertension (HR=1.889; 95% CI: 1.05～3.40; P<0.05) were independent risk factors for new atrial fibrillation after surgery. Multivariate regression analysis showed that only a high proportion of right ventricular septal pacing (HR= 5.572; 95% CI: 2.444～12.701; P<0.01) and hypertension (HR=2.752; 95% CI: 1.342～5.642; P<0.05) were independent risk factors for postoperative new atrial fibrillation. Half a year after operation, compared with LBBAP high group (223 ± 63) pg/mL, the NT proBNP level in RVSP high group (752 ± 54) pg/mL increased (P<0.01); Compared with RVSP low group (405 ± 48.7) pg/mL group, the NT proBNP level in RVSP high group increased (P<0.01). CONDLUSION LBBAP, as a more physiological pacing mode, reduces the proportion of new-onset AF. In this group, LBBAP does not have adverse effects on medium or long-term cardiac functions.