Calcification of the homograft and adhesions between the homograft and neoaorta may increase the difficulty of reoperation. The Ross procedure typically is reserved for younger patients with appropriate anatomy and tissue characteristics in whom anticoagulation is either contraindicated or undesirable, and it is per- formed only at Comprehensive Valve Centers by surgeons experienced in this procedure.12 14,32 11.2. Antithrombotic Therapy Recommendations for Antithrombotic Therapy for Prosthetic Valves Referenced studies that support the recommendations are summarized in Online Data Supplement 36. 