ABC | Volume 111, Nº1, July 2018

Original Article Warpechowski Neto et al Brugada syndrome – cohort and 19-year registry Arq Bras Cardiol. 2018; 111(1):13-18 Figure 2 – Discrimination of events in patients with implantable cardioverter defibrillator (ICD). ICD – Nonsustained supraventricular tachycardia ICD – Frequent premature ventricular complexes ICD – Ventricular fibrillation ICD – No arrhythmic event detected No implantable device 2 2 1 11 19 The male predominance found in this study, already reported in the initial description of the disorder as 75%, 1 is in accordance with data from the global literature, whose percentages range according to the geographic location: 84.3% in a large Japanese cohort, 5 70% in a Spanish cohort, 9 and 57.9% in a Belgian study. 10 The proportion is maintained in geographically close populations, such as an Argentinian cohort of similar size to ours (43 patients), whose male percentage reached 85%. 11 Likewise, the mean age of 43.89 years coincides with the findings of several populations studied, even those with larger samples, 12-14 clearly and repeatedly showing the impairment of young individuals with high productive capacity, emphasizing the importance of the correct identification of those at higher risk based on a common epidemiological profile. Although the history of ventricular arrhythmias of the fibrillation or tachycardia type is a predictor of mortality in patients with BrS, and the arrhythmia recurrence rates are around 7.7%per year, 14 most of our patients were asymptomatic at the time of the electrophysiological study. If, on the one hand, asymptomatic patients without additional risk factors are currently classified as of low risk, 14,15 on the other it is difficult to predict the potential risk based solely upon the ECG assessment, requiring a multifactorial approach in the search for other complications, such as family history of sudden death, personal history of syncope or induced arrhythmia, because the electrocardiographic pattern in isolation seems insufficient to define high risk for events. 16 The incorporation of the advances in cardiology in the search for risk predictors has diverging results in a scenario where the identification of susceptibility is the key point, and, because therapy showed no significant changes in past years, it remains without any effective pharmacological alternative, being limited to implantable antiarrhythmic devices. Such devices are known to have a significant, although indirect, contribution to the patients’ quality of life because of their daily social or professional repercussions, 17 adding arguments to the already challenging process of identifying its real beneficiaries. In 2003, the assessment of 547 patients with the BrS pattern and no previous history of sudden death, with a mean 24-month follow-up, a positive electrophysiological study was associated with arrhythmic outcomes on a multivariate analysis, with a 6-fold higher risk in 2 years versus a 2.5‑fold for the second better predictor, the previous history of syncope. 13 In a cohort 14 of 1029 patients (72% of men, mean age of 45 years, and 64% asymptomatic - a population profile similar to ours), the electrophysiological study was performed in 638 individuals and had a 41% positivity, but was not a risk predictor on multivariate analysis, leaving only personal history and electrocardiographic pattern correlated with events. Two years later, a prospective multicenter study, 15 assessing specifically the accuracy of arrhythmia induced by stimulation and the identification of new risk predictors, evidenced that induced arrhythmia was not an event predictor in a 36-month follow-up (and only 34% of the patients with induced arrhythmia experienced a new induction when repeating the protocol), in addition to the same findings regarding type I ECG and personal history of syncope, and the additional positive finding for ventricular refractory period shorter than 200 ms and QRS fragmentation. Of the 14 events, only 1 showed no spontaneous type I pattern, with a number needed to treat (NNT) of 25.2. In 2016, however, a systematic review of eight prospective observational studies involving 1312 patients (n ranging from 575 to 23) with BrS, no previous history of sudden death, undergoing ventricular stimulation, showed that induced arrhythmia correlated with events in a mean 38.3-month 16