Abstract Introduction Patients with D- transposition of the great arteries (TGA) treated with Senning or Mustard surgeries have high incidence of supraventricular tachycardias (SVTs). Accessing to the pulmonary venous atrium (PVAt) is frequently required to perform the ablation, however it can be challenging. Aim To investigate the differences between a retrograde aortic approach (Re-Aa) and transbaffle approach (TBa) for PVAt ablation in this set of patients. Methods Prospective observational study in a third level hospital since April 2018 until October 2022, with a medium-term follow-up. All consecutive patients (pt) with history of SVT and atrial switch surgery that underwent electrophysiologic study (EP) and electroanatomic mapping using a high-density Grid mapping catheter and a contact-force ablation catheter were included. Results A total of 25 EPs were performed in 20 pt (13 (52%) Female, median age 37 y.o [IQR 34-41], median follow-up time 13 month [IQR 10-37]). In 14 pt the PVAt was mapped and ablated via Re-Aa, and in 11 with TBa. Table 1 shows basal patients characteristics, note that no significant differences between groups were found. In 19 pt (76%) a CTI-dependent flutter was documented (10 (71%) in Re-Aa group and 9 (82%) in TBa, p=0.6). Furthermore, in 7 pt other tachycardia circuits were found. Accurate mapping of all the CTI walls were achieved with both strategies, however, the posterior PVAt wall and the pulmonary veins were suboptimal mapped with Re-Aa due to a lack of catheter contact. Acute ablation success was 83% in Re-Aa and 100% in TBa (p=0.5). Despite a higher recurrence rate in the Re-Aa in the first months (20% vs 0%), no significant differences in recurrences were found between groups within 1 year of follow-up (HR 1.3 [95%CI: 0,2-7], p=0.8) (FIGURE). Complication rate was 20% in Re-Aa and 0% in TBa. All complications were directly related to the arterial vascular access (1 femoral pseudoaneurysm, 1 iliac dissection, 1 mediastinal hematoma), and were successfully treated. Conclusion In D-TGA treated with atrial switch surgery, PVAt mapping and ablation is feasible with both strategies with a high acute success rate and without significant differences in recurrences at mid-term follow up. However, TBa is associated with a lower complications rate and also with a better catheter contact and accurate mapping in the PVAt posterior wall.

Transbaffle or retrograde aortic approach for atrial arrhythmias ablation in patients with D-TGA treated with atrial switch surgery