There are no ran- domized comparative-effectiveness trials evaluat- ing a strategy of bridging versus no bridging in adequate numbers of patients with prosthetic heart valves who need temporary interruption of oral anticoagulant therapy, although such studies are ongoing. The evidence cited to support bridg- ing therapy derives from cohort studies with poor or no comparator groups.1,6 14 In patient groups other than those with mechanical heart valves, increasing concerns have surfaced that bridging therapy exposes patients to higher bleeding risks without reducing the risk of thromboembolism.15 Accordingly, decisions about bridging should be individualized and should account for the trade- offs between thrombosis and bleeding. Recommendations for Bridging Therapy During Interruption of Oral Anticoagulation in Patients With Prosthetic Heart Valves (Continued) COR LOE Recommendations CLINICAL STATEMENTS AND GUIDELINES 11.4. Excessive Anticoagulation and Serious Bleeding With Prosthetic Valves Recommendations for Management of Excessive Anticoagulation and Serious Bleeding in Patients With Prosthetic Valves Referenced studies that support the recommendations are summarized in Online Data Supplement 37. COR LOE Recommendations For patients with mechanical valves and uncontrollable bleeding who require immediate reversal of anticoagulation, administration of 4-factor prothrombin complex (or its activated form) is reasonable. For patients with mechanical valves and uncontrollable bleeding who have received 4-factor prothrombin concentrate complex, adjunctive use of intravenous vitamin K is reasonable if resumption of VKA therapy is not anticipated for 7 days. For patients with bioprosthetic valves or annuloplasty rings who are receiving a direct oral anticoagulant and who require immediate reversal of anticoagulation because of uncontrollable bleeding, treatment with idarucizumab (for dabigatran) or andexanet alfa (for anti-Xa agents) is reasonable.1 5 For patients with a mechanical prosthetic valve and supratherapeutic INR (>5.0) who are not actively bleeding, the benefit of individualized treatment with oral vitamin K, in addition to temporary withdrawal of the VKA, is uncertain. 