Roca-Luque I, et al. - Researchers sought to delineate the types of intra-atrial re-entrant tachycardia (IART), circuit locations, and to analyze predictors of Cavotricuspid isthmus (CTI) vs non-CTI-related IART in this observational study including all consecutive patients with congenital heart disease (CHD) who underwent a first IART ablation in a single referral tertiary hospital from January 2009 to December 2015 (94 patients, 39.4% female, age: 36.55 ± 14.9 years, 40.4% with highly complex cardiac disease). Outcomes suggested CTI-related IART as the most frequent mechanism, although non-CTI-related IART was present in 49% (alone or with concomitant CTI-related IART). High-grade CHD complexity and non-typical ECG were noted to have a strong relationship with non-CTI IART.