Atrial tachycardia eliminated at the ventricular side in patients with congenitally corrected transposition of the great arteries: Electrophysiological findings and anatomical concerns.

Abstract Background The unique malformation of congenitally corrected transposition of the great arteries (cc-TGA) makes the pulmonary outflow tract (POT) a possible origin of atrial tachycardia (AT). Objective The purpose of this study was to investigate the mapping characteristics of ATs successfully ablated at the POT in cc-TGA patients. Methods Cc-TGA patients with AT eliminated at the POT were analyzed. Activation mapping of the atria and the POT was performed under the guidance of a 3-D electroanatomic mapping system. The activation pattern of these chambers was investigated, with the local activation time (LAT, using coronary sinus ostium as reference) of the earliest activation site (EAS) compared. Results AT eliminated at the POT was documented in 5/6 cc-TGA patients. The EAS was at the right anteroseptal region with LAT of 33 (21-120)ms in the right atrium, and at the septal wall with comparable LAT (26ms, 47ms and 26ms, P=0.604) in the left atrium. The EAS of the POT was in the vicinity of the left-facing pulmonary sinus cusp in 3 cases and the non-facing pulmonary sinus cusp in 2 cases, with LAT of 106 (28-134)ms preceding both atria. Ablation at this site successfully eliminated the AT in all 5 cases. Conclusions AT arising adjacent to the POT is not an uncommon tachycardia in patients with the situs solitus type cc-TGA, and can be safely eliminated by ablation targeting the EAS in the POT.