Electrical Synchrony Optimization for Left Bundle Branch Area Pacing in Patients With Bradycardia and Heart Failure

Clinical value of the fibrosis-4 index in predicting mortality in patients with right ventricular pacing

BACKGROUND

The fibrosis-4 (FIB-4) index has attracted attention as a predictive factor for cardiovascular events and mortality in patients with heart disease. However, its clinical value in patients with implanted pacemakers remains unclear.

METHODS

This study included patients who underwent pacemaker implantation. The FIB-4 index was calculated based on blood tests performed during the procedure. The primary outcome was all-cause mortality, and the secondary outcomes included cardiovascular death, non-cardiovascular death, and major adverse cardiovascular events (MACE; composite of cardiovascular death, heart failure hospitalization, non-fatal myocardial infarction, and non-fatal stroke). The FIB-4 index was stratified into tertiles. Between-group comparisons were performed using log-rank tests and multivariate analysis using Cox proportional hazards. The predictive accuracy and cut-off value of the FIB-4 index were calculated from the receiver operating characteristic curve for all-cause mortality. Finally, based on the calculated cut-off values, the patients were divided into two groups for outcome validation and subgroup analysis.

RESULTS

This study included 201 participants, of whom 38 experienced death during the observation period (median: 1097 days). All-cause mortality, non-cardiovascular death, and MACE differed significantly between groups stratified by the FIB-4 index tertiles (log-rank test: P<0.001, P<0.001, and P = 0.045, respectively). Using Cox proportional hazards analysis, the unadjusted hazard ratio was 4.75 (95% confidence interval [CI]: 2.05-11.0, P<0.001) for Tertile 3 compared to Tertile 1. After adjustment for confounding factors, including sex, the presence or absence of left bundle branch block at baseline, QRS duration during pacing, and pacing rate at the last check, the hazard ratio was 4.79 (95% CI: 2.04-11.2, P<0.001). The cut-off value of the FIB-4 index was 3.75 (area under the curve: 0.72, 95% CI: 0.62-0.82).

CONCLUSIONS

In patients with pacemakers, the FIB-4 index may be a predictor of early all-cause mortality, with a cut-off value of 3.75.

Feasibility study on cardiac resynchronization in the treatment of heart failure by single left bundle branch pacing

To examine the feasibility of single left bundle branch pacing for cardiac resynchronization therapy (CRT) by carrying out a frequency adaptive atrioventricular delay (RAAVD) algorithm and automatic optimization of the single left bundle branch pacing atrioventricular interval (AVI) based on the right atrioventricular interval (RAS-RVS). Thirty-six patients with CRT class Ia indications according to the European Society of Cardiology 2016 guidelines and implanted with RAAVD functional three-chamber pacemakers were prospectively enrolled in this study. Patients were divided into a single left bundle branch pacing group (n = 21) and a standard biventricular pacing group (n = 15). The optimization of the two groups was performed under standard cardiac colour Doppler ultrasound, followed by the comparison of the QRS width, cardiac function improvement, and echocardiography indicators. The ratio of AVI to the right atrial-right ventricular interval (RAS-RVS) after single LV pacing optimization was defined as the single left bundle branch pacing coefficient (LUBBPε). In comparison to the BVP, the QRS was significantly narrowed (P = 0.017), accompanied by a significantly increased proportion of patients with NYHA class I and II, as well as the 6MWT. Compared with standard biventricular pacing, LVEDD was significantly shortened (P = 0.045), accompanied by significantly improved LAD, AVVTI, EA distance/RR, IVMD, and TS-SD after the operation. RAS-RVS was 156 ± 33 ms, the optimized AVI was 102 ± 10 ms, and LUBBPε was calculated to be 0.66 ± 0.06. Depending on the LUBBPε, a three-chamber pacemaker with a single left bundle branch pacing system was developed based on RAS-RVS-optimized AVI automatically. A three-chamber pacemaker with single left bundle branch pacing can achieve CRT based on RAS-RVS, reaching the optimal AVI of 66% of RAS-RVS.