This patient should stop warfarin 5 days before his umbilical hernia repair surgery but requires no bridging anticoagulation. He is scheduled for an invasive procedure with a moderate or high risk of bleeding and therefore requires discontinuation of warfarin for surgery. Cessation of warfarin 5 days before surgery is typically sufficient to assure a normalized INR for the procedure. For patients requiring stoppage of chronic anticoagulation, the necessity of bridging anticoagulation must then be determined based on the patient's thromboembolic risk. Contemporary mechanical aortic valve prostheses have a low (<5%) annual risk of thromboembolism, and guidelines recommend no anticoagulation bridging for patients with these prostheses if they are in sinus rhythm and have no additional risk factors for arterial thromboembolism. Perioperative aspirin continuation in a patient whose only indication for antiplatelet therapy is a mechanical valve prosthesis is a matter of debate. The American College of Chest Physicians and the American College of Cardiology/American Heart Association both suggest that aspirin be continued throughout surgery in any patient in whom the antithrombotic benefits outweigh the bleeding risks. If aspirin is continued, the additional bleeding risk it confers should be factored into the decision making regarding bridging anticoagulation.

Both intravenous unfractionated heparin and therapeutic-dose subcutaneous enoxaparin are not appropriate in this patient. Either is an acceptable form of bridging anticoagulation for patients at intermediate or high risk of thromboembolism, but for patients with low thromboembolism risk, the potential bleeding complications of bridging outweigh the possible thromboembolism prevention. For bridging-eligible patients, low-molecular-weight heparin (LMWH) is often preferred because it can be administered in the outpatient setting and does not require laboratory monitoring; however, no evidence suggests any difference in outcomes with LMWH or unfractionated heparin.

Prophylactic-dose subcutaneous enoxaparin is only an acceptable choice for perioperative anticoagulation bridging in intermediate-risk (5%-10% annual rate of thromboembolism) patients on warfarin for a history of venous thromboembolism. For other chronic anticoagulation indications (atrial fibrillation and mechanical heart valves), no data are available to suggest a benefit from prophylactic-dose LMWH.