Baseline study is recommended with periodic follow-up CMR, with frequency of repeat imaging determined by anatomic and physiological findings. CCT may be used if CMR is not feasible. If CCT is used instead of CMR imaging, the frequency should be weighed against radiation exposure. 6-minute walk test or CPET, depending on clinical indication. ACHD indicates adult congenital heart disease; CCT, cardiac computed tomography; CCTGA, congenitally corrected transposition of the great arteries; CMR, cardiovascular magnetic resonance imaging; CPET, cardiopulmonary exercise test; ECG, electrocardiogram; and TTE, transthoracic echocardiogram. CLINICAL STATEMENTS AND GUIDELINES Diagnostic (Continued) IIb C-EO It may be reasonable to perform catheterization in asymptomatic adults after Fontan palliation to evaluate hemodynamics, oxygenation and cardiac function to guide optimal medical, interventional and/or surgical therapy. Therapeutic I C-EO Anticoagulation with a vitamin K antagonist is recommended for adults with Fontan palliation with known or suspected thrombus, thromboembolic events, or prior atrial arrhythmia, and no contraindications to anticoagulation. IIa C-LD Catheter ablation can be useful in adults after Fontan palliation with intra-atrial reentrant tachycardia or focal atrial IIa C-LD Fontan revision surgery, including arrhythmia surgery as indicated, is reasonable for adults with atriopulmonary Fontan connections with recurrent atrial tachyarrhythmias refractory to pharmacological therapy and catheter ablation who have preserved systolic ventricular function and severe atrial IIa B-R Pulmonary vasoactive medications can be beneficial to improve exercise capacity in adults with Fontan repair.S4.4.2-19 S4.4.2-25 IIb B-NR Antiplatelet therapy or anticoagulation with a vitamin K antagonist may be considered in adults after Fontan palliation without known or suspected thrombus, thromboembolic events, or prior IIb C-LD Reoperation or intervention for structural/ anatomic abnormalities in a Fontan palliated patient with symptoms or with failure of the Fontan circulation may be Synopsis Fontan repairs are the most common palliation of sin- gle ventricle physiology seen in adults. 