Local activation delay exacerbates local J-ST elevation in the epicardium: Electrophysiological substrate in Brugada syndrome

Introduction The mechanisms of J-ST elevation in the right precordial leads in patients with Brugada syndrome (BrS) remain controversial (ie, repolarization vs depolarization hypotheses). Recently, epicardial substrate ablation for late fractionated potentials and a low-voltage area (LVA) in the right ventricular outflow tract (RVOT) has been performed for ventricular fibrillation (VF) that is not controllable with medications. Epicardial ablation is reported to be effective for the suppression of VF recurrence, and it eliminates J-ST elevation in most cases. Unipolar electrodes used in the 3-dimensional mapping system are, however, generally recorded with different filters than those of surface electrocardiograms (ECGs). As such, we could not precisely compare the morphology of the J-ST segment in unipolar electrodes with those in surface ECGs. The relationship between J-ST elevation in surface ECGs and bipolar fractionated and low-amplitude electrograms in the RVOT epicardium remains unclear. We present a unique case of epicardial substrate mapping using unipolar electrodes with filter setting that is the same as surface ECGs (0.05–100 Hz). We investigated the correlation between unipolar J-ST elevation and bipolar abnormal potentials in a patient with BrS who had episodes of VF recurrence.