ABC | Volume 111, Nº1, July 2018

Original Article Cohort of Patients Referred for Brugada Syndrome Investigation in an Electrophysiology Service - 19-Year Registry Stefan Warpechowski Neto, Tiago Luiz Luz Leiria, Laura Lessa Gaudie Ley, Antonio Lessa Gaudie Ley, Luiza Zwan Dutra, Leonardo Martins Pires, Marcelo Lapa Kruse, Gustavo Glotz de Lima Instituto de Cardiologia - Fundação Universitária de Cardiologia (IC/FUC), Porto Alegre, RS - Brazil Mailing Address: Tiago Luiz Luz Leiria • Av. Princesa Isabel, 370. Postal Code 90620-000, Santana, Porto Alegre, RS – Brazil E-mail: pesquisa.leiria@gmail.com , editoracao-pc@cardiologia.org.br Manuscript received October 10, 2017, revised manuscript February 22, 2018, accepted February 22, 2018 DOI: 10.5935/abc.20180094 Abstract Background: Brugada syndrome (SBr) is an arrhythmic condition characterized by ST-T segment abnormalities in the right precordial leads associated with a high risk of ventricular arrhythmias and sudden death. Local data regarding the clinical characteristics of patients with a typical electrocardiographic (ECG) pattern undergoing electrophysiological study are scarce. Objective: To evaluate patients with an ECG pattern suggestive of SBr referred for electrophysiological evaluation in a specialized center. Methods: Cohort study of patients referred for electrophysiological study because of an ECG pattern compatible with SBr between January 1998 and March 2017. Results: Of the 5506 procedures, 35 (0.64%) were for SBr investigation, 25 of which (71.42%) were performed in men. The mean age was 43.89 ± 13.1 years. The ECG patterns were as follows: type I, 22 (62.85%); type II, 12 (34.30%); and type III, 1 (2.85%). Twenty-three patients (65.7%) were asymptomatic, 6 (17.14%) had palpitations, 5 (14.3%) had syncope, and 3 (8.6%) had a family history of sudden death. Electrophysiological study induced ventricular tachyarrhythmias in 16 cases (45.7%), the mean ventricular refractory period being 228 ± 36 ms. Ajmaline / procainamide was used in 11 cases (31.4%), changing the ECG pattern to type I in 7 (63.6%). Sixteen cases (45.7%) received an implantable cardioverter defibrillator (ICD). In a mean 5-year follow-up, 1 of the 16 patients (6.25%) with ICD had appropriate therapy for ventricular fibrillation. There was no death. Other arrhythmias occurred in 4 (11.4%) cases. Conclusions: Most patients are men, and a type I ECG pattern is the main indication for electrophysiological study. Class IA drugs have a high ECG conversion rate. The ICD event rate was 6%. (Arq Bras Cardiol. 2018; 111(1):13-18) Keywords: Brugada Syndrome; Ventricular Tachycardia; Sudden Death. Introduction Brugada syndrome (BrS) is a genetic arrhythmogenic disorder characterized by typical electrocardiographic changes of the ST-T segment in the right precordial leads (V1-V3), associated with an increased risk for sudden death due to ventricular arrhythmias, mainly polymorphic ventricular tachycardia, in the absence of structural heart disease. 1 The BrS was first described in 1992, relates to the loss of function in the sodium ion channels of ventricular cardiomyocytes and results from the decrease in that channel amount and failure of expression, its voltage change, time‑dependent action and accelerated or prolonged inactivation recovery, 2 leading to a reduction in the sodium ion inflow and in the physiological duration of the action potential. Despite its autosomal dominant inheritance, BrS is currently known to be sporadic in two‑thirds of its cases (65%), 3 due to mutations leading to the failure of the SCN5A gene function that encodes sodium channels – initially re-written in 1998 4 – or to other 350 pathogenic mutations in several sodium, potassium or calcium channel genes, currently representing percentages of genetic changes lower than 35%. Because of its multifactorial etiology that involves the contribution of genetic, environmental and hormonal factors, the clinical manifestation varies, affecting mainly men (proportion of 8-9:1), 5 with clinical onset, on average, at the age of 40 years, and major outcome of sudden death triggered by sleep, vagotonia or fever. Brugada syndrome accounts for 20% of the sudden cardiac deaths with structurally normal hearts 6 and 4-12% of all sudden cardiac deaths. 7 This study describes a cohort of patients referred for electrophysiological study at the Instituto de Cardiologia/ Fundação Universitária de Cardiologia do Rio Grande do Sul (ICFUC), over the past 19 years (1998-2017), after finding an electrocardiographic pattern suggestive of BrS in different situations of medical care. 13