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 secondary outcomes included cardiovascular and non-cardiovascular death. 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. Results This study included 201 participants, of whom 38 (incidence rate: 5.8/100 person-years) experienced death events during the observation period (median: 1097 days). All-cause and non-cardiovascular death differed significantly between groups stratified by the FIB-4 index tertiles (log-rank test: P <0.001 and P <0.001, 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 age, 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 3.61 (95% CI: 1.37–9.48, P =0.009). The cut-off of the FIB-4 index was 3.75 (area under the curve: 0.72, 95% CI: 0.62–0.82). Conclusions The FIB-4 index was a potential predictive factor for all-cause mortality in patients with implanted pacemakers.