Catheter ablation in transposition of the great arteries with Mustard or Senning baffles

Complete transposition of the great arteries (D-TGA) accounts for 5% to 7% of congenital heart defects. Although the arterial switch procedure has now replaced atrial redirection as the surgical procedure of choice, most adults today with D-TGA have had Mustard or Senning baffles. These surgeries involve extensive atrial reconstruction and predispose to sinus node dysfunction and atrial tachyarrhythmias. By 20 years after surgery, the prevalence of atrial tachyarrhythmias is approximately 25%, continues to increase with time, and is similar among patients with Mustard or Senning baffles. In our experience, intra-atrial reentrant tachycardia (IART) is the most common arrhythmia substrate, followed by nonautomatic focal atrial tachycardia (NAFAT) and atrioventricular (AV) nodal reentrant tachycardia. Accessory-pathway-mediated tachyarrhythmias and atrial fibrillation occur less frequently.

Sudden cardiac death is the most common cause of death in patients with D-TGA and Mustard or Senning baffles, with a risk that exceeds that of tetralogy of Fallot. Importantly, observational studies have linked atrial arrhythmias to increased risk of sudden death, and a multicenter study of implantable cardioverter-defibrillator recipients suggests that supraventricular arrhythmias may trigger ventricular arrhythmias. In IART, atrial tachycardia rates tend to be slower than with typical atrial flutter, leading to 1:1 conduction, which in turn may result in hemodynamic instability. This phenomenon is potentially compounded by ineffective atrial transport, subendocardial ischemia of the systemic right ventricle, and systemic ventricular dysfunction. Therefore, an aggressive management strategy to prevent rapidly conducting atrial tachyarrhythmias is generally advisable. Catheter ablation is often considered the definitive treatment of choice.