A case report of J wave syndrome with abnormal potentials in both right and left ventricles and reversed J wave in lead V1.

Background: Abnormal epicardial potentials in J wave syndrome predominantly involve the right ventricular outflow tract (RVOT), while left ventricular (LV) involvement remains less characterized and associates with increased ventricular fibrillation (VF) risk. We report a case demonstrating an inverted J wave in lead V1, suggesting LV posterior wall substrate rather than typical RVOT involvement. Case summary: A 19-year-old man with resuscitated VF received a subcutaneous implantable cardioverter-defibrillator (S-ICD). Despite cilostazol and quinidine therapy, he experienced five appropriate shocks within 6 months. Twelve-lead electrocardiography showed inferior J waves and a negative deflection in V1, suggesting an inverted J wave. Epicardial mapping showed fractionated potentials in both RVOT and LV posterior wall. Pilsicainide administration augmented RVOT potentials while attenuating those in the LV posterior wall. Spontaneous VF was triggered by premature ventricular contractions (PVCs) originating from the LV posterior wall, where prepotentials preceded QRS onset by 50 ms. Radiofrequency applications eliminated the PVCs, followed by anatomical ablation of RVOT fractionated regions. Subsequently, VF was never induced by program stimulation of up to triple extra stimuli. In the post-operative electrocardiogram, inverted J waves in the V1 lead Discussion: This case demonstrates complex electrophysiological manifestations of J wave syndrome, with the inverted J wave in V1 potentially reflecting LV posterior wall substrate. Although the overlapping ablation procedure limited definitive attribution, these findings contribute to understanding the heterogeneous substrates in J wave syndrome.