LAUSR

Introduction Scar-mediated atrial and ventricular arrhythmias are leading indications for hospitalization and risk factors for sudden cardiac death in the postoperative congenital heart population. Successful transcatheter arrhythmia ablation would, in turn, decrease hospitalizations, improve patient quality of life, and drive down healthcare costs. Arrhythmia mapping and ablation in these patients, however, is plagued by lowvoltage substrates, multiple circuits, and tachycardia recurrence. Herein, we discuss a patient with congenitally corrected transposition of the great arteries who underwent a double-switch procedure and subsequently developed atrial arrhythmias that were refractory to antiarrhythmic therapy and antitachycardia pacing. Transcatheter ablation using high-density mapping delineated his complex arrhythmia circuit, permitting successful ablation.