Identifying the high-risk Brugada syndrome patient: Let us get personal

Abstract

There are several reasons why risk stratification in the Brugada syndrome (BrS) continues to pose significant challenges. Prevalence of the syndrome in the general population is low, yet high-risk individuals can manifest with sudden cardiac death at a young age when the implantable cardioverter-defibrillator comes with a heavier burden of lifestyle change and cumulative long-term complications. Many patients will be asymptomatic on presentation and electrocardiographic (ECG) changes can fall in a nondiagnostic category. Despite significant and ongoing advancements in genetic discovery and technology, the yield of genetic testing in overall patients with BrS remains well below 50%. 1 The 2005 Consensus Conference established that conversion of a nondiagnostic ECG (saddle pattern type 2 or 3 ECG) to a diagnostic ECG (type 1 Brugada pattern) with a sodium-channel blocker (SCB) test indicated a positive diagnosis of the BrS. 1 This is an important issue, since increased awareness of this condition has resulted in a referral stream to electrophysiologists and cardiologists of patients with a nondiagnostic Brugada-pattern ECG who have vague or no symptoms. However, more recently, the largest BrS registry (FINGER Registry, 1029 consecutive subjects from 4 European countries) concluded that event rates in asymptomatic patients with BrS were low (0.5% per year) and that inducibility of ventricular arrhythmias and family history of sudden cardiac death were not predictive of sudden cardiac death. 2 Spontaneous type 1 ECG changes and the presence of symptoms were the only predictors of arrhythmic events in this population. In this issue of HeartRhythm, Zorzi el al 3 specifically address the utility of the SCB test among 198 patients with a nondiagnostic Brugada-pattern ECG recruited at 2 medical centers of the Veneto region of Italy. Of the total, 27 who developed spontaneous type 1 ECG changes were excluded and 18 were not available for follow-up. The remaining 153 subjects with type 2 or 3 Brugada ECGs were followed up for a mean period of 59 months. A positive SCB test result was associated with a significantly higher event rate in symptomatic patients but not in asymptomatic patients. These results suggest that the clinical utility of the SCB test in asymptomatic patients with nondiagnostic ECGs is likely to be low. This careful study incorporated placement of the right precordial leads in a superior position in order to increase sensitivity for detecting type 1 ECG changes. 4 What is the clinical message of this study and what are the caveats to keep in mind? The findings of this study provide more evidence to clinicians that SCB testing may not be indicated in asymptomatic patients with a nondiagnostic Brugada-pattern ECG. We should keep in mind that this was a relatively small study with a relatively short follow-up period given the natural history of the BrS. Also, event rates were low and the study did not provide information on pre-2005 (Consensus Conference publication) vs post-2005 clinical management. Most important, if the findings of the FINGER registry remain consistent, our clinical attention is likely to focus largely on symptomatic patients with a spontaneous type 1 BrS ECG.