Scar and arrhythmic isthmus characterization in patients with D-TGA treated with atrial switch surgery using a new high density mapping grid catheter

Abstract Introduction Patients with D- transposition of the great arteries (TGA) treated with Senning or Mustard surgeries have several atrial scars that predispose them to develop atrial tachycardias (AT). Identification of scar zones and possible arrhythmic isthmus in voltage mapping will help to guide the ablation. Aim To describe the feasibility of using a specific mapping catheter to identify possible arrhythmic isthmus in this set of patients. Methods Prospective observational study in patients with history of SVT and atrial switch surgery, that underwent electrophysiologic study (EP) and electroanatomic (EA) mapping with a new 8Fr deflectable, multipoint wavefront-activation-orientation independent Grid catheter, in a third level hospital since April 2018 until January 2020, with medium-term follow-up. Results A total of 9 EPs were performed in 8 patients (3 (37,5%) Female, median age 35.2 y.o. (IQI 29,2–37,6)). Figure 1A shows an example of an activation and substrate mapping. Figure 1B shows the localization and percentage of scar identified in both atria. A total of 7 tachycardias were induced. In this, an arrhythmogenic isthmus was identified and in all patients at least one non-arrhytmogenic isthmus was documented. Figure 1C shows anatomical and electrophysiological characteristics of the isthmus. Arrhythmogenic isthmus had slower conduction velocity than non-arrhytmogenic (mean 0,31m/s (IQI 0,14–0,63) vs 0,94 m/s (IQI 0,81–1,24) p=0.02) and fractionated potentials were detected more frequently (100% vs 55% p=0.05) Conclusion EA mapping with a new a multipoint, high-definition, Grid Cather allows the identification and electrophysiological characterization of arrhythmogenic and non-arrhytmogenic isthmus in patients with TGA treated with atrial switch surgery. Figure 1 Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Hospital Universitari Vall d'Hebron. VHIR