What is the perioperative management of Warfarin (coumarin) for a patient with a prosthetic mitral valve and a history of cerebrovascular accident (stroke)?

From the Guidelines

Perioperative management of warfarin for a patient with a prosthetic mitral valve and history of stroke requires careful bridging therapy to minimize both thrombotic and bleeding risks, with the most recent guidelines from 2021 suggesting an INR target of 3.0 (range, 2.5–3.5) for patients with mechanical mitral valve replacement 1.

Key Considerations

• The patient should discontinue warfarin 5 days before surgery to allow the INR to normalize (below 1.5) 1.
• During this period, therapeutic-dose low molecular weight heparin (LMWH) such as enoxaparin 1 mg/kg twice daily should be initiated when the INR falls below 2.0, with the last dose given 24 hours before surgery.
• For patients with mechanical mitral valves, this bridging is essential due to their high thrombotic risk.
• Postoperatively, LMWH should be restarted 24-48 hours after surgery once hemostasis is adequate, and warfarin should be resumed at the patient's usual maintenance dose when oral intake is possible.
• The LMWH should be continued until the INR returns to the therapeutic range (typically 2.5-3.5 for mitral mechanical valves) 1.

Additional Recommendations

• For minor procedures with low bleeding risk, warfarin may be continued without interruption, maintaining the INR at the lower end of the therapeutic range.
• Close monitoring of INR values and coordination between cardiology, neurology, and surgical teams is crucial for optimal outcomes.
• The addition of aspirin to warfarin therapy may be considered in patients with a history of ischemic stroke or TIA before the mechanical valve surgery, as it may provide additional protection against recurrent thromboembolic events 1.

From the FDA Drug Label

For patients with AF and prosthetic heart valves, anticoagulation with oral warfarin should be used; the target INR may be increased and aspirin added depending on valve type and position, and on patient factors. For all patients with mechanical prosthetic heart valves, warfarin 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).

The management of Warfarin perioperatively for someone with a prosthetic mitral valve and a history of stroke involves maintaining a target INR of 3.0 (range, 2.5 to 3.5) with Warfarin therapy, and considering the addition of aspirin depending on patient factors 2.

• The target INR may need to be adjusted based on the individual patient's risk factors and response to therapy.
• The decision to stop or continue Warfarin perioperatively should be made on a case-by-case basis, taking into account the patient's risk of thromboembolic events and bleeding complications.
• It is essential to closely monitor the patient's INR levels and adjust the Warfarin dose accordingly to minimize the risk of complications.

From the Research

Perioperative Management of Warfarin

To manage Warfarin perioperatively for someone with a prosthetic mitral valve and a history of stroke, the following considerations should be taken into account:

• The American College of Chest Physicians recommends an INR range of 2.5-3.5 for patients with a mechanical mitral valve 3.
• For patients with a mechanical mitral valve and a history of systemic embolization, an INR of 2.5-3.5 combined with low-dose aspirin (80-100 mg) is recommended 3.
• The optimal target INR for warfarin therapy in patients who have undergone implantation of a prosthetic mechanical mitral valve is 2.5-3.5 4.
• A study comparing low-dose warfarin (target INR, 2.0-2.5) to standard-dose warfarin (target INR, 2.5-3.5) in patients with an On-X mechanical mitral valve found that low-dose warfarin did not achieve noninferiority for the composite primary end point of thromboembolism, valve thrombosis, and bleeding events 5.

Bridging Therapy

When warfarin needs to be discontinued for surgical procedures, bridging therapy with low-molecular-weight heparin (LMWH) may be necessary:

• A standardized low-molecular-weight heparin bridging regimen has been proposed, with LMWH started 3 to 4 days before surgery and continued for 6 days after surgery 6.
• The dosage of LMWH depends on the patient's thromboembolic risk, with high-risk patients receiving 70 anti-factor Xa U/kg twice daily and moderate- to low-risk patients receiving prophylactic once-daily doses 6.

Antithrombotic Therapy

The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy provides guidelines for antithrombotic therapy in valvular heart disease:

• For patients with mechanical prosthetic heart valves, vitamin K antagonists are recommended, with a target INR of 3.0 (range, 2.5 to 3.5) for tilting disk valves and bileaflet mechanical valves in the mitral position 7.
• For patients with bioprosthetic valves, vitamin K antagonists with a target INR of 2.5 (range, 2.0 to 3.0) are recommended for the first 3 months after valve insertion in the mitral position 7.