Prevalence of Brugada Syndrome in a Large Population of Young Singaporean Men

Brugada syndrome ◼ male population ◼ prevalence B rugada syndrome is a hereditary cardiac channelopathy with an increased risk of sudden cardiac death (SCD).The worldwide prevalence of Brugada syndrome is estimated to be 0.05%. 1 It has a male preponderance and has been reported to be more prevalent in Southeast Asia, 1 a heterogeneous region populated by many different ethnic groups.Expert consensus proposes Brugada syndrome to be diagnosed when a type I ST-segment elevation is observed either spontaneously or after intravenous administration of a sodium channel blocking agent in at least 1 right precordial lead V 1 and V 2 , without requiring any further evidence of malignant arrhythmia. 2 Although Brugada syndrome prevalence has been studied, there is a paucity of drug-induced provocation methods in large community-based studies.On the basis of consensus criteria, 2 we aimed to investigate the true prevalence of Brugada syndrome in a large, young, Southeast Asian population with incorporation of a flecainide challenge.All Singaporean men undergo preconscription medical examination before compulsory military service.Demographic, anthropometric, and ECG variables were collected prospectively from January 2015 to December 2016.Individuals with ECGs suspicious of Brugada pattern (of any type), and/or known family history of Brugada syndrome or SCD (cutoff of ≤45 years old) were referred for evaluation by a certified cardiac electrophysiologist.In addition, transthoracic echocardiogram was performed to exclude structural heart disease.Brugada syndrome was diagnosed in those manifesting type 1 Brugada ECG morphology, while those with nondiagnostic ECG were offered a flecainide challenge with informed consent.A positive flecainide challenge result was defined as the provocation of a type 1 ECG pattern.Patients with a final diagnosis of Brugada syndrome were followed up for 2 years for arrhythmia or SCD.The research protocol was approved by the local institutional review board.Informed consent waiver was granted because patient data were obtained from an existing registry effort.A schematic diagram illustrating the evaluation of suspected Brugada individuals is shown (Figure).A total of 54 599 consecutive male subjects (mean age, 18.7±1.6years) composed of 37 855 Chinese (69.3%), 10 374 Malays (19.0%), 4989 Indians (9.1%), and 1381 from other ethnic groups (2.5%) underwent screening.Of these, 840 individuals were referred for further evaluation of suspected Brugada syndrome.After review by an electrophysiologist, 553 were deemed to have electrocardiographically normal variants and 287 (0.53% of the screened cohort) had type 1, 2, or 3 Brugada pattern ECG.None had significant structural heart disease on echocardiographic assessment.Spontaneous type 1 ECG pattern was present in 3 individuals.The other 284 individuals had ECG features consistent with type 2 or 3 patterns and were offered flecainide challenge.Of the individuals, 75.4% (n=214/284) underwent the provocation test.Of these, 24.8% (n=53/214) had a positive result and were diagnosed with Brugada syndrome.