The use of any strategy must be balanced against the risk of bleeding. VKAs remain the cornerstone of therapy Recommendations for Antithrombotic Therapy for Prosthetic Valves (Continued) COR LOE Recommendations CLINICAL STATEMENTS AND GUIDELINES for patients with mechanical valve prostheses. Oral anti- thrombin and anti-Xa agents are not approved for use in these patients. The addition of mono- or dual-antiplatelet therapy to VKA treatment for other indications (eg, acute coronary syndrome or percutaneous coronary interven- tion [PCI]) must be done with caution. The evidence base for the optimal antithrombotic strategy across subgroups of patients who have received a bioprosthetic valve is not robust. Practice patterns around the use of antiplatelet and anticoagulant medications in these patients vary as a function of method of implantation (surgical versus transcatheter), the presence of any independent indica- tion for anticoagulation (eg, AF, venous thromboembolic disease), and local/institutional care pathways (Figure 12). Recommendation-Specific Supportive Text 1. All patients with mechanical valves require life- long anticoagulant therapy with a VKA.1 5 In addi- tion to the thrombogenicity of the intravascular prosthetic material, mechanical valves impose abnormal flow conditions, with zones of low flow within their components, as well as areas of high-shear stress, which can cause platelet activa- tion that leads to valve thrombosis and embolic events. Therapy with an oral VKA at an INR goal appropriate for the comorbidity of the patient and the type and position of the mechanical valve prosthesis is required to decrease the incidence of thromboembolism and associated morbid- ity. Data show that anticoagulation with a VKA is protective against valve thrombosis (OR: 0.11; 95% CI: 0.07 0.2) and thromboembolic events (OR: 0.21; 95% CI: 0.16 0.27). 