PO-623-01 ABLATION STRATEGIES IN PATIENTS WITH CONGENITAL HEART DISEASE AND ATRIAL BAFFLES

Abstract

Patients with D-Transposition of the Great Arteries (D-TGA) palliated with atrial switch have a high incidence of atrial arrhythmias and pose a particular challenge for ablation. We sought to analyze ablation strategies in this population. An in-depth analysis of ablation data in patients with D-TGA, atrial baffles, and atrial arrhythmia ablations performed at a large tertiary care institution. A cohort of 26 patients with D-TGA and atrial switch (73% male; systemic RV EF 35±11%, mean age at first ablation 37.4±7.2 years) underwent a total of 31 procedures, 26 de novo and 5 redo ablations. For patients with no prior intervention (21, 81%), ablation revealed cavotricuspid isthmus dependent flutter (CTI-flutter, 71%), scar-related intra-atrial reentry (IART, 57%), and focal atrial tachycardia (FAT, 9.5%) (Figure A). Patients with prior outside interventions for CTI-flutter (5, 29%) demonstrated conduction across the CTI in 3/5 (60%) cases. However, patients requiring redo ablation after an index ablation at our institution (5, 29%) demonstrated bi-directional block across the CTI and different, new arrhythmia substrates at the next procedure (80% IART, 40% FAT). Intracardiac echocardiography and electroanatomic mapping were used in all contemporary cases. A screw-in atrial lead was used in 4 procedures as a stable fiduciary reference for mapping, as the coronary sinus ostium was inaccessible. Achieving bi-directional block across the CTI often required ablating on both sides of the baffle (retroaortic access, 81%; using a baffle leak, 11.5%; trans-baffle puncture, 7.7%, or using a VSD, 3.8%). Combined approaches were necessary in 23% of patients to reach critical tissue and achieve optimal contact force (Figure B). Irrigated contact force sensing catheters were used, targeting a significant effect on the electrograms and demonstration of bi-directional CTI block (Figure C). Despite the complex anatomy and atrial reconstruction, cavotricuspid isthmus flutter is still the most common arrhythmia in this population, and bi-directional block often requires additional ablation approaches to reach the target tissue on either side of the baffle. Once CTI block is achieved, further recurrences are due to different, new arrhythmia substrates- IART and FAT.