Brugada burden in Brugada syndrome: The way to go in risk stratification?

Abstract

Better means for risk stratification of patients with asymptomatic Brugada syndrome are urgently needed. To begin with, the majority of Brugada syndrome patients encountered nowadays consistently belong to this category (63% of Brugada syndrome patients in Japan and 64% of those in Europe are asymptomatic when diagnosed). Moreover, in contrast to patients with long QT syndrome, who often have warning symptoms in the form of recurrent syncope before they develop cardiac arrest, arrhythmias in the Brugada syndrome often are lethal when they first occur. On the other hand, the absolute risk of developing spontaneous ventricular fibrillation (VF) among asymptomatic patients is lower than previously estimated. Until recently, electrophysiologic studies (EPS) were proposed to virtually all patients with asymptomatic Brugada syndrome based on the premise that patients with inducible VF are more likely to develop similar spontaneous arrhythmias. Unfortunately, original encouraging reports were not confirmed. Combined analysis of the largest studies suggests that the risk for spontaneous VFwithin 4 to 5 years is 2.6% for inducible patients and 1.8% for noninducible patients, not much of a difference. In the recent, prospective PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) study, the risk was actually higher (albeit without reaching statistical significance) for patientswithout inducible VF: 4.9% of noninducible patients, but only 3.9% of those inducible, had spontaneous VF within 3 years. Importantly, limiting the definition of “positive EPS” to VF induction with≤ double ventricular extrastimulation, or to VF induced from the right ventricular apex (S. Priori, Personal Communication, March 16, 2013), does not improve the predictive accuracy of EPS. Therefore, it is time to seek alternative means of risk stratification.