Electrocardiographic clues for understanding J-wave syndromes

J-wave syndromes refer to a group of conditions of inherited arrhythmia disorders that can present with sudden cardiac death due to polymorphic ventricular arrhythmias (1). In some cases, the only clue to the diagnosis of these infrequent conditions is surface electrocardiogram (ECG) (2). One important point that all physicians should keep in mind is that only the presence of the ECG pattern does not constitute the syndrome (2). Several individuals will develop the ECG pattern (either spontaneously or upon certain clinical conditions), and their risk of sudden death may not differ from their counterparts without the ECG manifestation. The most commonly investigated and extensively reported J-wave syndromes in the literature are Brugada syndrome (BrS) (3) and early repolarization syndrome (ErS) (2). Both can affect young individuals with no prior history of cardiovascular disease, can coexist with “apparently” normal hearts (on initial cardiac screening including echocardiogram), and are characterized by J-point elevation (1-3). The morphology of the ST-segment and T-wave following the J-point elevation helps physicians to electrocardiographically differentiate one from the other (4). A consensus on BrS (3) has classified the type of ECG phenotypes into two variants (type-1 or “coved” and type-2 or “saddleback”), and a more recent consensus on ErS (2) has characterized the early repolarization pattern into “malignant” (more frequently associated with ErS) and “benign” (frequently seen in healthy individuals and athletes), which could be considered as a variant of normality.