Significance of left posterior extension of early repolarization in patients with J-wave syndrome

BACKGROUND J waves in the inferior or lateral leads are characteristic electrocardiographic (ECG) changes in patients with early repolarization syndrome (ERS). However, the presence of J waves in the left posterior region has not yet been evaluated.OBJECTIVE The purpose of this study was to clarify the significance of J waves in the posterior left ventricle using leads V7-V9 and a body surface mapping (BSM) system.METHODS Forty patients diagnosed with ERS were included. All patients exhibited J waves in either the contiguous inferior, lateral, or posterior leads. We evaluated the incidence of J waves in the inferolateral and posterior leads using a 15-lead ECG with synthesized V7-V9 and an 87-lead BSM. Additionally, we assessed the arrhythmogenicity of the posterior regions based on the morphology of the premature ventricular complexes (PVCs) associated with ventricular fibrillation (VF).RESULTS J waves were observed in the lateral, inferior, and posterior leads of 26 (65%), 31 (78%), and 39 (97%) patients, respectively. J waves were found only in the posterior leads of 5 patients. BSM was evaluated in 9 patients, all of whom exhibited a positive area on the posterior region. PVCs associated with VF were recorded in 5 patients. Among patients with inferolateral and posterior J waves, all except 1 patient who displayed left bundle branch block morphology showed PVCs originating from the posterior left ventricular region.CONCLUSION Posterior J waves are common in ERS patients. This abnormality can be detected using leads V7-V9 and the BSM system and may be associated with arrhythmogenesis.