Risk stratification of asymptomatic patients with Brugada type or J-wave type ECG.

diopathic ventricular fibrillation (VF) has been recognized as a cause of unexplained nocturnal sudden death in middle-aged men, especially in South-East Asian countries. In some of these patients with idiopathic VF, a high takeoff ST segment and prominent J wave in the right precordial ECG leads (Brugada type) or inferolateral leads (J-wave type) have been reported.1,2 A prominent transient outward current (Ito) may play an important role in the genesis of the J wave.3 Both the Brugada type and J-wave type of idiopathic VF have some similar clinical characteristics, such as VF episodes at night, male predominance, familial occurrence, triggered by high fever, suppression by isoproterenol, and exacerbation by β-blockers. Because of the similarities between the 2 types, “J-wave syndromes” was proposed by Antzelevitch and Yan.3