Electrophysiological Study in Ebstein's Anomaly With no Evidence of Accessory Pathway

Ebstein's anomaly (EA) is characterized by low implantation of the tricuspid valve, and corresponds to less than 1% of all congenital heart defects1-3. It is often associated with other malformations, such as ventricular septal defect, and Wolff-Parkinson-White syndrome often accompanies. Its clinical manifestation depends on the severity of the anatomical changes, and the indications for surgery have been well established4,5. When anomalous pathways are associated with EA, in one third of the cases the electrocardiographic pattern can differ from the classic one (short PR interval and presence of delta wave), because of slow intra-atrial conduction or anomalous pathway of long and slow conduction6. Arrhythmias are usually present in up to 80% of the patients7, with prevalence of anomalous atrioventricular pathways ranging from 0 to 44%1-3. Despite the universal acceptance of electrophysiological study (EPS) in symptomatic patients or in those with apparent accessory pathway on the electrocardiogram (ECG), data on asymptomatic patients with no electrocardiographic evidence of pre-excitation are scarce in the literature. Because of postoperative implications (difficult access to certain left atrial areas after surgical repair, risk of tachyarrhythmias in the intra- and postoperative periods, and likelihood of intraoperative elimination of accessory pathway), we report a case in which preoperative EPS was performed in a patient with EA and no classical evidence of tachyarrhythmias.