Abstract 12187: Arrhythmia Substrate and Approaches for First-Time and Repeat Catheter Ablation in Patients With D-transposition of the Great Arteries and Atrial Baffles

Abstract

Introduction: Atrial arrhythmias are common in patients with D-TGA and atrial switch. We sought to analyze the arrhythmia substrate and catheter ablation approaches and outcomes. Methods: We performed a retrospective review of all clinical and procedural data in patients with D-TGA followed at a large tertiary care center. Results: In a cohort of 152 patients (mean age 30±11 years), atrial tachycardia was present in 69(45%) patients. Ablations were performed in 39(26%) patients: macro-reentrant atrial flutter (N=37), atrial fibrillation (N=4), and focal automatic atrial tachycardia (N=3). Detailed electrophysiology study data was available for 34 patients. At first ablation (N=28), cavo-tricuspid isthmus dependent flutter (CTI, 23(82%)) was most common, followed by right atriotomy-related flutter (IART, 16(57%)) and focal atrial tachycardia (FAT, 1(3.5%)). Bidirectional CTI block often required ablation on both sides of the baffle to complete the isthmus line. Access to the pulmonary venous atrium was obtained in 82% of first-time ablations (via retrograde aortic access, 74%, baffle puncture, 6%, or baffle fenestration, 12%) and in 100% of redo procedures. The first ablation was acutely successful in 25 (89%) patients; the other 3 patients had either partial procedural success (1), failed ablation (1), or underwent an empirical ablation (1). Long-term arrhythmia recurrence occurred in 13(46%) after the first ablation and class III antiarrhythmic medications were utilized in 12 patients. At least one long-term recurrence occurred in 11(44%) patients. Importantly, clinical arrhythmia burden was significantly reduced post-ablation, with rare and short-limited episodes amenable to antiarrhythmic drugs or cardioversion. Repeat ablation was required in 3 cases. Long-term arrhythmia recurrence after a previously completed CTI line involved different arrhythmia mechanisms: scar-related reentry (80%) and automatic atrial tachycardia (40%). Conclusions: Atrial arrhythmia in patients with D-TGA often involves the CTI and atriotomy scars. Ablation of the CTI typically requires access to the pulmonary venous atrium to achieve bidirectional block. Despite late recurrence, the clinical arrhythmic burden is substantially improved.