CLINICAL STATEMENTS AND GUIDELINES Kleindorfer Synopsis Patients with congenital heart disease represent a group at higher risk of ischemic stroke and systemic throm- particularly in the presence of cya- notic or other complex anatomic lesions.574 577 In these patients, it is reasonable to start oral anticoagulant ther- apy with a VKA (warfarin) for the secondary prevention of stroke or TIA of presumed cardioembolic origin after careful individual assessment of the competing bleed- ing risks associated with oral anticoagulation. Fontan repair is associated with high risk of atrial arrhythmias, intracardiac thrombosis related to atrial scarring, and right-to-left shunting from Fontan fenestration.578 580 Patients with Fontan palliation and known or suspected thrombus, ischemic stroke or TIA, or prior atrial arrhyth- mia should be treated with warfarin in the absence of Recommendation-Specific Supportive Text 1. The Fontan circulation is a palliative approach to complex single-ventricle physiology and is associ- ated with complex hemodynamics related to an obligatory chronic elevation in central venous pres- sure and reduced cardiac output.30 Consideration for antithrombotic therapy in Fontan patients should take into account the high prevalence of thrombus formation and potentially catastrophic impact of pulmonary or systemic thromboembo- lism. The physiology associated with the Fontan circulation may lead to stroke/TIA via different mechanisms. The associated ventricular dysfunc- tion and abnormal ventricular morphology, the progressive atrial scarring from the Fontan sur- gery, and the elevated intra-atrial pressures may trigger atrial arrhythmias, increasing the risk of The role of DOACs in patients with Fontan is less defined, and thus far, the published evidence is limited to small obser- Given the lack of conclusive evidence on the safety of DOACs in the presence of the hepatic dysfunction and altered coagula- tion in patients who underwent Fontan palliation, warfarin should be considered the preferred oral anticoagulant regimen. 2. 