Bradyarrhythmias and Brugada syndrome: clinical features, long-term outcome and prognostic implications —the BruBra study

Brugada syndrome (BrS) is an inherited arrhythmia syndrome associated with ventricular arrhythmias (VA) and sudden cardiac death (SCD).1 Furthermore, it is associated with sick sinus syndrome (SSS) and atrioventricular conduction disease (AVCD) with reported incidences of 1.1–1.7% and 2.7%, respectively.2–6 It was further hypothesized that specific SCN5A mutations may be associated with significant bradyarrhythmias.7 Whether bradyarrhythmias represent independent phenotypic manifestations or correlate with increased VA risk remains uncertain. This study aims to explore the prognostic significance of bradyarrhythmias in BrS patients. This retrospective, multicenter study included BrS patients with ECG-documented non-vagal bradycardia, defined as SSS [symptomatic sinus arrest ≥3 s, asymptomatic arrest >6 s, or chronotropic incompetence requiring pacemaker (PM) implantation], AVCD [second degree atrioventricular (AV) block or higher], or both (binodal disease). The study was approved by the Swiss local ethics committee (BASEC 2025-00524; Rif. CE 4807), whereas all other centres were responsible for their local approvals. BrS diagnosis was established according to latest guidelines.1 Patients were divided into three groups: isolated SSS, isolated AVCD, and binodal disease. Primary endpoint was VA occurrence, defined as sustained ventricular tachycardia or ventricular fibrillation. Secondary endpoints were all-cause death and device related complications. Continuous variables are presented as median (first–third quartile). Categorical variables were compared using Fisher’s exact or Chi-square test, as appropriate. Continuous variables were analysed using the Mann–Whitney U test. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression. Given the limited number of events, multivariable modelling was not performed to avoid overfitting. A two-sided P-value