What is the management of preoperative anticoagulation for patients with mechanical prosthetic heart valves (MHV)?

From the Guidelines

Management of preoperative anticoagulation for patients with mechanical prosthetic valves should be individualized, considering the risk of thromboembolism and bleeding, and bridging therapy with heparin may not be necessary for all patients, as suggested by the most recent study 1. The decision to bridge or not should be based on the patient's specific risk factors, such as the type of valve, presence of atrial fibrillation, or history of thromboembolism.

• For patients with bileaflet mechanical aortic valve replacement (AVR) and no other risk factors, the risk of thromboembolism after stopping anticoagulation with a vitamin K antagonist (VKA) is small, and bridging anticoagulation may not be necessary, as stated in the 2021 ACC/AHA guideline 1.
• For high-risk patients, such as those with mechanical mitral valve replacement (MVR) or additional risk factors, bridging therapy with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin may be considered, as recommended in the 2017 AHA/ACC focused update 1.
• The PERIOP-2 trial, a randomized study, found no significant difference in major thromboembolism or major bleeding between patients with mechanical heart valves who received bridging therapy and those who did not, as reported in the 2022 American College of Chest Physicians clinical practice guideline 1.
• The management strategy should balance the risk of thromboembolism from inadequate anticoagulation against the risk of perioperative bleeding, as mechanical valves carry a high risk of thrombosis when anticoagulation is subtherapeutic.
• Postoperatively, bridging anticoagulation should resume once hemostasis is adequate, typically 24-48 hours after surgery, with warfarin restarted as soon as the patient can take oral medications, as suggested by the 2021 ACC/AHA guideline 1.
• The choice of bridging therapy, either low-molecular-weight heparin or unfractionated heparin, should be based on the patient's renal function, risk of bleeding, and other individual factors, as recommended in the 2017 AHA/ACC focused update 1.

From the FDA Drug Label

For all patients with mechanical prosthetic heart valves, warfarin is recommended. For patients with a St. Jude Medical (St. Paul, MN) bileaflet valve in the aortic position, a target INR of 2.5 (range, 2.0 to 3. 0) is recommended. For patients with tilting disk valves and bileaflet mechanical valves in the mitral position, the 7th ACCP recommends a target INR of 3.0 (range, 2.5 to 3.5). For patients with caged ball or caged disk valves, a target INR of 3.0 (range, 2.5 to 3. 5) in combination with aspirin, 75 to 100 mg/day is recommended.

The management of preoperative anticoagulation for mechanical prosthetic valve involves the use of warfarin with a target INR that varies depending on the type and position of the valve.

• For a St. Jude Medical bileaflet valve in the aortic position, the target INR is 2.5 (range, 2.0 to 3.0) 2.
• For tilting disk valves and bileaflet mechanical valves in the mitral position, the target INR is 3.0 (range, 2.5 to 3.5) 2.
• For caged ball or caged disk valves, the target INR is 3.0 (range, 2.5 to 3.5) in combination with aspirin, 75 to 100 mg/day 2. It is essential to note that the management of anticoagulation should be individualized and based on the patient's specific condition and valve type.

From the Research

Management of Preoperative Anticoagulation

• The management of patients with mechanical prosthetic valves who are taking anticoagulants and require non-cardiac surgery varies widely 3.
• For minor surgery, no adjustment of anticoagulation is undertaken if the International Normalized Ratio (INR) is less than 4.0, and local hemostatic methods and tranexamic acid mouthwashes are used 3.
• For major surgery, warfarin is stopped preoperatively and low-molecular-weight heparin is used 3, 4.
• For emergency surgery, partial reversal of anticoagulation with low-dose parenteral vitamin K is obtained 3.

Bridging Anticoagulation

• A standardized periprocedural anticoagulation regimen with low-molecular-weight heparin is associated with a low risk of thromboembolic and major bleeding complications in patients at increased risk for arterial thromboembolism who require temporary interruption of warfarin therapy 4.
• The American College of Chest Physicians (ACCP) recommends starting warfarin with unfractionated heparin or low-molecular-weight heparin for at least five days and continuing until a therapeutic INR is achieved 5.
• When invasive procedures require the interruption of oral anticoagulation therapy, recommendations for bridge therapy are determined by balancing the risk of bleeding against the risk of thromboembolism 5, 6.

Target INR for Mechanical Prosthetic Valves

• The optimal target INR for warfarin therapy in patients who have undergone implantation of a prosthetic mechanical mitral heart valve is 2.5-3.5 for new generation valves and 3.5-4.5 for older types of valves 7.
• Warfarin therapy should be administered to maintain stable INR values, ensuring the lowest possible variation in the intensity of anticoagulation 7.
• In selected patients with a history of thromboembolic disease and/or coronary artery disease, consideration should be given to supplementing warfarin with low-dose aspirin 7.