Predictive value of Shanghai score system in patients with drug-induced type 1 Brugada electrocardiographic pattern

Background: The Shanghai score system was developed to enhance the risk stratification in Brugada Syndrome (BrS); however, its prognostic value in drug-induced type 1 BrS remains unclear. Methods: This study involved 698 patients with drug-induced type 1 BrS, confirmed via pharmacologic challenge (flecainide or ajmaline), from 21 centers in Italy and Switzerland. Patients were classified according to the Shanghai score system: probable/definite BrS (score ≥ 3.5) and possible BrS (score < 3.5). The primary outcome was appropriate ICD therapy or sudden cardiac death (SCD)/sustained ventricular arrhythmias; the secondary outcome includes the identification of clinical predictors of primary outcome events. Kaplan-Meier and Cox regression analyses were used. Results: Our study population included 239 patients (34.2%) with probable/definite BrS and 459 (65.8%) patients with possible BrS. During a median follow-up of 57.4 months, 20 patients (2.9%) experienced the primary outcome. Kaplan-Meier analysis revealed a significantly lower event rate in possible BrS (0.11% over 10 years) compared to probable/definite BrS (0.42%). SCN5A pathogenic variants were a significant predictor of primary endpoint in the possible BrS group (OR: 12.5). Conclusions: Shanghai score system for BrS diagnosis may be useful as a tool for risk stratification of life-threatening arrhythmias among patients with drug-induced type I BrS ECG. Identifying the SCN5A mutations is of pivotal importance for refining the risk stratification.