Individual-level meta-analysis of all randomized tri- als to determine whether PFO size is independently associated with response to treatment. Given the evidence that residual shunts after PFO device closure are associated with increased risk of stroke recurrence,570 studies to determine the optimal prevention strategy in this setting, including consideration of a second device closure or lifelong anticoagulant therapy. Large long-term prospective registries of patients with PFO closure to assess the risk of device- associated AF and the risks associated with device complications such as device erosion, fracture, and 5.5. Congenital Heart Disease Recommendations for Congenital Heart Disease Referenced studies that support recommendations are summarized in online Data Supplements 40 and 41. COR LOE Recommendations In patients with ischemic stroke or TIA and Fontan palliation, anticoagulation with warfarin is recommended to reduce the risk of recur- rent stroke or TIA.572,573 In patients with cyanotic congenital heart disease and other complex lesions, ischemic stroke or TIA of presumed cardioembolic origin, therapy with warfarin is reasonable to reduce the risk of recurrent stroke or TIA. 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. 