Does aortic valve replacement (AVR) require anticoagulation?

From the Guidelines

Patients who undergo mechanical aortic valve replacement (AVR) require lifelong anticoagulation with a vitamin K antagonist (VKA) to achieve an INR of 2.5 (range, 2.0-3.0), while those with tissue AVR typically require anticoagulation for a limited time, usually 3 months, with a target INR of 2.0-3.0. The decision to extend anticoagulation is based on individual patient risk factors, such as atrial fibrillation, previous thromboembolism, or hypercoagulable state 1.

Key Considerations

• Mechanical AVRs have a higher risk of thromboembolism and require lifelong anticoagulation to reduce this risk 1.
• Tissue AVRs have a lower risk of thromboembolism, but anticoagulation is still necessary for a limited time to prevent early valve thrombosis and systemic embolism 1.
• The target INR for mechanical AVRs is 2.5 (range, 2.0-3.0), while for tissue AVRs, it is 2.0-3.0 for the initial 3-month period 1.
• Patients with additional risk factors for thromboembolism may require longer-term or lifelong anticoagulation, and the decision should be made on an individual basis 1.

Anticoagulation Regimens

• Mechanical AVRs: Lifelong anticoagulation with a VKA to achieve an INR of 2.5 (range, 2.0-3.0) 1.
• Tissue AVRs: Anticoagulation with a VKA for the first 3 months after surgery, with a target INR of 2.0-3.0, followed by low-dose aspirin (75-100 mg daily) for long-term therapy 1.
• Patients with risk factors for thromboembolism: Longer-term or lifelong anticoagulation may be necessary, and the decision should be made on an individual basis 1.

From the Research

Aortic Valve Replacement and Anticoagulation

• The need for anticoagulation after aortic valve replacement (AVR) is a topic of ongoing debate, with various studies presenting different findings 2, 3, 4, 5, 6.
• Some studies suggest that anticoagulation may not be necessary for patients without thromboembolic risk factors after biological AVR, as it does not confer any additional benefits in terms of reducing ischemic events, but may increase the risk of bleeding 3, 6.
• However, other studies recommend the use of anticoagulation, such as warfarin, for the first three months after biological AVR, although the risk/benefit ratio is unclear 5.
• A meta-analysis comparing oral anticoagulants (OAC) alone versus OAC with antiplatelet therapy (APT) following transcatheter aortic valve replacement (TAVR) in patients with atrial fibrillation found that OAC alone was associated with a lower risk of major or life-threatening bleeding, but similar rates of stroke and mortality 4.
• Another study found that plasma anticoagulation with warfarin during the early postoperative phase was inferior to platelet aggregation inhibition by aspirin in terms of postoperative bleeding risk, cerebral ischemic events, and survival 5.

Anticoagulation Regimens

• Different anticoagulation regimens have been compared in various studies, including warfarin, aspirin, and antiplatelet therapy 3, 5, 6.
• A study found that aspirin was associated with a lower risk of bleeding and similar rates of cerebral ischemic events and survival compared to warfarin after biological AVR 5.
• Another study found that none of the antithrombotic regimens, including anticoagulation, antiplatelet therapy, and combination therapy, showed benefits in stroke or survival at 3 or 12 months after biological AVR, and that anticoagulation increased bleeding events 6.

Clinical Implications

• The findings of these studies have important implications for clinical practice, suggesting that anticoagulation may not be necessary for all patients after AVR, and that the risk/benefit ratio should be carefully considered on an individual basis 3, 4, 5, 6.
• Further studies are needed to clarify the optimal antithrombotic regimen and duration of therapy following AVR, and to determine which patients are at highest risk of bleeding and thromboembolic events 2, 4.