[Late atrial tachycardia after Fontan-type procedure. Cooperative study of 52 cases]

The Fontan procedure has allowed to improve the outcome of complex congenital cardiopathy involving single ventricle. A better understanding of the systemic venous circulation has favored bicavo-bipulmonary derivation instead of atrio-pulmonary derivation. However, in spite of the improvement in surgical procedures, post-operative arrhythmias still occur with an increasing rate during follow-up reaching 40 to 50% of the patients in some series. We report a series of 52 patients of which 92% presented a severe atrial arrhythmia (atrial fibrillation or atrial flutter) during a 6-year follow-up. The outcome was worse in case of classic or modified Fontan (n=15) or direct dicavo-bipulmonary procedures (n=7). The non-modified Fontan group was characterized by a lower functional class (63% NYHA class I or II), more refractory atrial arryhthmias (37%), more deaths or transplanted patients (26%). Amiodarone was very effective in this context as opposed to the failure of class 1 anti-arrhythmic drugs. However, low dosage amiodarone in combination with a beta-blocker is recommended taking into account the important rate of amiodarone-induced side effects (53%). Atrial arrhythmia ablation was unsuccessful (8/10 failures). Anti-arrhythmic surgery (N=3) has been incompletely evaluated. In summary, transformation of failing Fontan procedures into bicavo-bipulmonary derivations seems to offer the best outcome at the price of a high surgical risk.