Are Mechanical Heart Valve Replacements Linked to Higher Thromboembolism Risk?

Is a mechanical valve replacement considered to be at high risk for thromboembolism?

Hello Dr.
Wu: Is a patient with a mechanical valve replacement at high risk for thromboembolism? For a patient undergoing knee joint replacement surgery, what should the INR be maintained at?

Lin Zhongnan, 40~49 year old female. Ask Date: 2021/01/29

Dr. Wu Xueming reply Cardiology

Patients with mechanical heart valve replacements need to take oral anticoagulants long-term to prevent thrombosis.
When undergoing surgery, they should be switched to intravenous anticoagulants preoperatively to allow for dosage adjustments and to maintain appropriate anticoagulation levels.
(At this time, aPTT is monitored, not INR.)

Reply Date: 2021/01/29

More Info

Mechanical heart valve replacements are indeed associated with a higher risk of thromboembolism compared to biological valves. This increased risk is primarily due to the nature of mechanical valves, which can create turbulent blood flow and promote platelet activation and clot formation. Patients with mechanical valves are typically prescribed anticoagulants, such as warfarin, to mitigate this risk. The goal of anticoagulation therapy is to maintain a therapeutic International Normalized Ratio (INR) that balances the risk of thromboembolism against the risk of bleeding.

For patients with mechanical heart valves, the recommended INR range is generally between 2.5 and 3.5, depending on the specific type of valve and the patient's individual risk factors. For instance, patients with aortic mechanical valves may require an INR of 2.0 to 3.0, while those with mitral mechanical valves may need an INR of 2.5 to 3.5. It's crucial for patients to have their INR monitored regularly to ensure it remains within the therapeutic range, as fluctuations can lead to either thromboembolic events or bleeding complications.

In addition to anticoagulation, patients with mechanical heart valves should be aware of other risk factors that can contribute to thromboembolism. These include the presence of atrial fibrillation, a history of previous thromboembolic events, and certain comorbid conditions such as heart failure or hyperlipidemia. Lifestyle modifications, such as maintaining a healthy diet, engaging in regular physical activity, and avoiding smoking, can also play a role in reducing thromboembolic risk.

Regarding your question about knee joint replacement surgery, it is essential to maintain the INR within the therapeutic range during the perioperative period. The management of anticoagulation around the time of surgery can vary based on the type of surgery and the patient's overall health. Typically, for elective surgeries like knee replacements, anticoagulants may be temporarily paused, and bridging therapy with low molecular weight heparin (LMWH) may be initiated to reduce the risk of thromboembolism during the period when warfarin is held.

In conclusion, mechanical heart valve replacements do carry a higher risk of thromboembolism, necessitating careful management of anticoagulation therapy. Patients should work closely with their healthcare providers to establish an appropriate INR target and to monitor their anticoagulation status regularly, especially when undergoing surgical procedures. It is also advisable to discuss any concerns regarding surgery and anticoagulation management with your healthcare team to ensure a safe and effective treatment plan.

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