Atrial scarring following an atrial based repair of transposition of great arteries is an important concern which has lead to the introduction and acceptance of arterial switch as the better choice. The likelihood of maintenance of sinus rhythm decreases progressively as years pass by after a Mustard operation, being seventy two percent at one year, fifty six percent at five years and just forty three percent at thirteen years. The reason could be damage to the sinus node area during surgery as well as damage to the internodal conduction pathways and scars acting as nidus for reentry circuits [Gillete PC, Kugler JD, Garson Ajr, Gutgesell HP, Duff DF, McNamara DG. Mechanisms of cardiac arrhythmias after the Mustard operation for transposition of the great arteries. Am J Cardiol 1980;45:1225-30]. Recurrent atrial flutter may need ablation, though it may require a retrograde arterial approach because the focus may be in the pulmonary venous canal.