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. Complex congenital heart disease is associated with an increased risk of stroke in adults.574 576 Mandalenakis et al575 conducted a large pro- spective registry in Sweden and documented an almost 11-fold increase in the risk of ischemic stroke in patients with congenital heart disease compared with control subjects matched by age, with the highest risk among patients with complex lesions. In a retrospective large database includ- ing >29000 adult (age >18 years) patients with congenital heart disease, Lanz et al574 reported an overall risk of ischemic stroke of 6.1% in women and 7.7% in men. In addition, in this study, patients with complex congenital heart disease had the highest risk (8.9% [95% CI, 6.0 11.5]). The mech- anisms underlying such an increased risk of stroke are different and multifactorial and are related to the high prevalence of atrial arrhythmias, risk for paradoxical embolization (eg, cyanotic congeni- tal heart disease), atrial mechanical dysfunction resulting from the presence of scar, and associ- ated hyperviscosity/hypercoagulability caused by chronic hypoxemia. In patients with cyanotic and other complex congenital heart disease and isch- emic stroke or TIA of presumed cardioembolic origin, treatment with warfarin is reasonable in the absence of contraindications to oral anticoagula- tion (eg, increased risk of bleeding). 