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

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 patients with cc-TGA.

Methods: Patients with cc-TGA with AT eliminated at the POT were analyzed. Activation mapping of the atria and POT was performed under the guidance of a 3-dimensional electroanatomic mapping system. The activation pattern of these chambers was investigated, with the local activation time (LAT; using coronary sinus ostium as a reference) of the earliest activation site (EAS) being compared.

Results: AT eliminated at the POT was documented in 5 of 6 patients with cc-TGA. The EAS was at the right anteroseptal region with a LAT of 33 (21-120) ms in the right atrium and at the septal wall with a comparable LAT (26, 47, and 26 ms; P = .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 nonfacing pulmonary sinus cusp in 2 cases, with a LAT of 106 (28-134) ms preceding both atria. Ablation at this site successfully eliminated AT in all 5 cases.

Conclusion: AT arising adjacent to the POT is not an uncommon tachycardia in patients with situs solitus-type cc-TGA and can be safely eliminated by ablation targeting the EAS in the POT.