J Wave Syndromes as a Cause of Sudden Arrhythmic Death

Accentuated J waves have been associated with idiopathic ventricular tachycardia and fibrillation (VT/VF) for nearly three decades. Prominent J waves characterize both Brugada and early repolarization syndromes leading to their designation as J wave syndromes. An early repolarization (ER) pattern, characterized by J point elevation, slurring of the terminal part of the QRS and ST segment elevation was considered to be a totally benign electrocardiographic manifestation until a decade ago. Recent casecontrol and population-based association studies have advanced evidence that an ER pattern in the inferior or infero-lateral leads is associated with increased risk for life-threatening arrhythmias, named early repolarization syndrome (ERS). ERS and Brugada syndrome (BrS) share similar electrocardiogram features, clinical outcomes, risk factors as well as a common arrhythmic platform related to amplification of I_to-mediated J waves. Although BrS and ERS differ with respect to the magnitude and lead location of abnormal J wave manifestation, they are thought to represent a continuous spectrum of phenotypic expression, termed J wave syndromes. A classification scheme for ERS has been proposed: type 1, displaying an ER pattern predominantly in the lateral precordial leads, is considered to be largely benign; type 2, displaying an ER pattern predominantly in inferior or infero-lateral leads, is associated with a higher level of risk; whereas type 3, displaying an ER pattern globally in inferior, lateral and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with VF storms.