Clinical Characteristics and Risk Stratification in Symptomatic and Asymptomatic Patients with Brugada Syndrome: Multicenter Study in Japan

Background: Neither the clinical characteristics nor risk stratification in Brugada syndrome have been clearly determined. We compared the clinical and ECG characteristics of symptomatic and asymptomatic patients with Brugada syndrome to identify new markers for high-risk patients. Methods: A total of 188 consecutive individuals with Brugada syndrome (mean age 53 ± 14 years, 178 males) were enrolled in the Japan Idiopathic Ventricular Fibrillation Study (J-IVFS). Clinical and ECG characteristics were evaluated in three groups of patients: Ventricular fibrillation (VF) group: patients with documented VF (N = 33); Syncope (Sy) group: patients with syncope without documented VF (N = 57); and asymptomatic (As) group: subjects without symptoms (N = 98). Their prognostic parameters were evaluated over a 3-year follow-up period. Results: (1) Clinical characteristics: incidence of past history of atrial fibrillation (AF) was significantly higher in the VF and Sy groups than in the AS group (P = 0.04). (2) On 12-lead ECG, r-J interval in lead V2 and QRS duration in lead V6 were longest in the VF group (P = 0.001, 0.002, respectively). (3) Clinical follow-up: during a mean follow-up period of 37 ± 16 months, incidences of cardiac events (sudden death and/or VF) were higher in the symptomatic (VF/Sy) groups than in the As group (P < 0.0001). The r-J interval in lead V2 ≥ 90 ms and QRS duration in lead V6 ≥ 90 ms were found to be possible predictors of recurrence of cardiac events in symptomatic patients. Conclusions: Prolonged QRS duration in precordial leads was prominent in symptomatic patients. This ECG marker may be useful for distinguishing high- from low-risk patients with Brugada syndrome.