A 57-year-old woman undergoes aortic valve replacement with a bileaflet mechanical valve for bicuspid aortic valve stenosis after an episode of syncope. Her past medical history is also significant for hypertension. Preoperative coronary angiogram showed no evidence of coronary artery disease and postoperative course was uncomplicated. Six months later, she comes to the physician for follow-up. Her medications include aspirin, warfarin, amlodipine, and candesartan. Transthoracic echocardiogram shows a mildly enlarged left atrium, left ventricular ejection fraction of 60%, a normally functioning mechanical aortic valve, and normal aortic root size. Which of the following is the best treatment option for this patient?

Question

A 57-year-old woman undergoes aortic valve replacement with a bileaflet mechanical valve for bicuspid aortic valve stenosis after an episode of syncope.  Her past medical history is also significant for hypertension.  Preoperative coronary angiogram showed no evidence of coronary artery disease and postoperative course was uncomplicated.  Six months later, she comes to the physician for follow-up.  Her medications include aspirin, warfarin, amlodipine, and candesartan.  Transthoracic echocardiogram shows a mildly enlarged left atrium, left ventricular ejection fraction of 60%, a normally functioning mechanical aortic valve, and normal aortic root size.  Which of the following is the best treatment option for this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_be38_649b_8f63_49a1ed0a7355_MD0005_00 The risk of systemic thromboembolism (eg, stroke) is approximately 4% per patient per year in those with mechanical prosthetic valves with no anticoagulation, compared to about 2% in patients treated with aspirin, and <1% in patients treated with warfarin. Patients with mechanical mitral valves have twice the risk compared to those with aortic valve prostheses. Therefore, long-term treatment with aspirin and warfarin is recommended for all patients with mechanical aortic or mitral valve replacement to reduce the rates of systemic thromboembolism. Current guidelines on the target International Normalized Ratio (INR) vary with the valve position (aortic vs mitral), type of mechanical valve, and associated comorbid conditions. In patients with mechanical aortic valve and no other risk factors (eg, atrial fibrillation, severe left ventricular dysfunction [ejection fraction <30%], prior thromboembolism, presence of hypercoagulable state), guidelines recommend long-term treatment with aspirin and warfarin to achieve a goal INR of 2.0-3.0.(Choice A) Patients who cannot take warfarin due to bleeding complications may benefit from aspirin therapy alone. (Choice C) INR goal of 2.5-3.5 is recommended in patients with mechanical mitral valves and those with mechanical aortic valves and associated risk factors. (Choices D and E) Combined antiplatelet (aspirin) and anticoagulant (warfarin) therapy significantly reduces the risk of thromboembolism and mortality compared to anticoagulant therapy alone. Educational objective: Antithrombotic therapy with aspirin and warfarin is recommended for all patients with mechanical aortic or mitral valve replacement to reduce the rates of systemic thromboembolism. Target International Normalized Ratio (INR) for aortic valves without risk factors is 2.0-3.0. Target INR for mechanical aortic valves with high-risk features (eg, atrial fibrillation, left ventricular dysfunction [ejection fraction <30%], prior thromboembolism, presence of hypercoagulable state) and mechanical mitral valves is 2.5-3.5. References: Antithrombotic and thrombolytic therapy for valvular disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/22315272)

A 57-Year-Old Woman Undergoes Aortic Valve Replacement with a Bileaflet