What is the recommended anticoagulation regimen for patients with mechanical aortic valves?

From the Guidelines

Patients with mechanical aortic valves should receive lifelong anticoagulation with warfarin, targeting an INR of 2.0-3.0, as recommended by the most recent guidelines 1. This recommendation applies to patients with bileaflet mechanical aortic valves in normal sinus rhythm without additional risk factors for thromboembolism. For patients with older-generation mechanical valves (ball-in-cage or tilting disc) or those with additional risk factors such as atrial fibrillation, previous thromboembolism, left ventricular dysfunction, or hypercoagulable conditions, a higher INR target of 2.5-3.5 is recommended 1. Some key points to consider include:

• Low-dose aspirin (75-100 mg daily) should be added to warfarin therapy for all patients with mechanical valves unless contraindicated 1.
• INR should be monitored regularly, initially weekly until stable, then monthly.
• Direct oral anticoagulants (DOACs) like apixaban and rivaroxaban are contraindicated in patients with mechanical valves 1.
• Warfarin is preferred over other vitamin K antagonists due to its predictable dose response and extensive clinical experience 1. The anticoagulation regimen is necessary because the artificial valve surfaces activate the coagulation cascade, creating a high risk of thrombus formation and subsequent thromboembolism that can lead to stroke or systemic embolism 1. It's also important to note that the risk of anticoagulation-related complications is greater for mechanical valves in the systemic atrioventricular (mitral) valve position 1. Overall, the goal of antithrombotic therapy is to achieve an optimal balance between the risks of thromboembolism and bleeding, and warfarin remains the preferred anticoagulant for patients with mechanical aortic valves 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. The duration of therapy in each patient should be individualized. In general, anticoagulant therapy should be continued until the danger of thrombosis and embolism has passed.

The recommended anticoagulation regimen for patients with mechanical aortic valves is warfarin with a target INR of 2.5 (range, 2.0 to 3.0). The duration of therapy should be indefinite, as anticoagulant therapy should be continued until the danger of thrombosis and embolism has passed, which is typically for the lifetime of the patient with a mechanical aortic valve 2.

From the Research

Anticoagulation Regimen for Mechanical Aortic Valves

The recommended anticoagulation regimen for patients with mechanical aortic valves varies depending on the type of valve, patient risk factors, and other considerations.

• The American College of Chest Physicians recommends an INR range of 2-3 for patients with a bileaflet mechanical valve in the aortic position 3.
• For patients with a mechanical valve in the mitral position, an INR of 2.5-3.5 is recommended, or an INR of 2-3 in combination with aspirin (80 mg/day) 3.
• Patients with a mechanical valve and a history of systemic embolization should have an INR of 2.5-3.5 combined with low-dose aspirin (80-100 mg) 3.

Duration of Warfarin Treatment

There is limited data on the optimal duration of warfarin treatment for patients with mechanical aortic valves.

• One study found that warfarin targeted at an INR of 1.8 (range 1.5-2.0) plus aspirin is safe and effective in patients with an On-X aortic mechanical valve, with a median follow-up duration of 3.4 years 4.
• Another study reported a case of a patient who had stopped taking warfarin 2 years after having a mechanical aortic valve replacement, with no thromboembolic events or mechanical failure for 24 years 5.

Intensity of Anticoagulation

The optimal intensity of anticoagulation for patients with mechanical aortic valves is still a topic of debate.

• One study found that standard-intensity anticoagulation (INR goal 2.5) was associated with a lower risk of thromboembolic events, bleeding, and all-cause death compared to higher-intensity anticoagulation (INR goal 3.0) 6.
• Another study suggested that an INR goal of 2.5 to 3.5 may be appropriate for patients with risk factors for thromboembolism, while an INR goal of 1.5 to 2.5 may be suitable for low-risk patients with an On-X aortic valve 7.