Bioprosthetic Valves :  The risk of thromoboembolism is limited to the first three months, until the sewing ring gets endothelialised. The recommendation is to have less intense regimen of anticoagulation (INR 2-2.5) for all mitral bioprostetic valves. As the incidence of thromoembolism is less for aortic bioprosthesis

anticoagulation is considered to be optional in many centers. They are put on aspirin and persantin. However patients with mitral bioprosthesis who are in AF, who has very large LA and has LA thrombus with history 01 thromboembolism should have long-term low-level anticoagulation.