Predictive Factors for New-Onset Left Bundle Branch Block in Patients with Left Ventricular Systolic Dysfunction and Its Prognostic Value

It remains unclear whether elevated ventricular wall pressure and left ventricular enlargement in patients with left ventricular systolic dysfunction (LVSD) can lead to left bundle branch block (LBBB). In this study, 801 consecutive hospitalized patients with a left ventricular ejection fraction of < 50% were enrolled. The primary outcome was the occurrence of new-onset LBBB or heart failure-related hospitalization, all-cause mortality, ventricular tachycardia, or implantation of an implantable cardioverter-defibrillator (ICD) /cardiac resynchronization therapy (CRT). During a median follow-up of 56 months, 70 cases of new-onset LBBB were observed, with a cumulative incidence rate of 10.1%. Multivariate Cox regression analysis demonstrated that paroxysmal atrial fibrillation (PAF) (hazard ratio [HR] 2.907, 95% confidence interval [CI] 1.552-5.444, P = 0.001), coronary artery disease (CAD) (HR 6.680, 95% CI 3.451-12.930, P < 0.001), dilated cardiomyopathy (DCM) (HR 6.394, 95% CI 3.501-11.675, P < 0.001), QRS duration (HR 1.018, 95% CI 1.010-1.027, P < 0.001), left ventricular end-diastolic dimension (LVEDD) (HR 1.032, 95% CI 1.006-1.059, P = 0.016), and β-blockers (HR 0.327, 95% CI 0.199-0.536, P < 0.001) were independent predictors of new-onset LBBB. A Kaplan-Meier survival curve analysis demonstrated that patients with new-onset LBBB had a higher incidence of composite endpoint events (P < 0.001), heart failure-related hospitalization (P < 0.001), and ventricular tachycardia or implantation of an ICD or CRT (P < 0.001) than patients without new-onset LBBB. Moreover, new-onset LBBB (HR 1.603, 95% CI 1.207-2.129, P = 0.001) was an independent predictor of composite endpoint events.DCM, LVEDD, CAD, PAF, and QRS duration were independent predictive factors for the subsequent development of LBBB in patients with LVSD. New-onset LBBB was independently associated with a poor prognosis.