A 70-year-old man comes to the office due to 6 months of progressive fatigue and dyspnea. He has had no fever, night sweats, or weight loss. The patient's medical history is significant for benign prostatic hyperplasia, hypertension, and mechanical aortic valve replacement for severe aortic stenosis. The patient currently takes warfarin, tamsulosin, and amlodipine. He does not drink alcohol. Temperature is 36.4 C (97.5 F), blood pressure is 150/99 mm Hg, and pulse is 68/min. BMI is 27 kg/m². The patient appears well nourished and fit. No scleral icterus is present, but the mucosa is pale. There is no jugular venous distension or lymphadenopathy. Cardiac examination reveals a normal S1 and a mechanical S2. Pulmonary examination is normal. Both the liver and the spleen are palpable. The remainder of the examination shows no abnormalities. Laboratory results are as follows: Which of the following is the best next step in management?

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This patient with a mechanical aortic valve developed symptomatic anemia and reticulocytosis, raising strong suspicion for traumatic macrovascular hemolysis. Most cases arise in the setting of a dysfunctional mechanical or severely calcified aortic valve; high pressure gradients across the irregular valve cause shearing of passing erythrocytes, leading to intravascular hemolysis. Damaged erythrocytes that are not lysed in the intravascular space are generally destroyed by splenic macrophages, leading to concurrent extravascular hemolysis. Mechanical aortic valves often cause mild, asymptomatic hemolysis. However, valve deterioration can trigger progressive symptomatic anemia (eg, fatigue, dyspnea with exertion) with signs of erythrocyte lysis (eg, jaundice, dark urine) and reticulocytosis. Thrombocytopenia can also occur because platelets may be damaged as they pass through the rigid valve opening. Hepatosplenomegaly can develop as the fragmented erythrocytes are cleared in the macrophages and monocytes within the liver and spleen. Peripheral blood smear generally shows schistocytes (helmet cells). A transthoracic echocardiogram should be performed to visualize valve function and determine valvular pressure gradients. schistocytes (Choice A) ADAMTS-13, a plasma protease that cleaves ultralarge von Willebrand fibers, is deficient in thrombotic thrombocytopenic purpura (TTP). Patients with TTP frequently have acute (not chronic) anemia due to microangiopathic hemolysis. Severe thrombocytopenia (<10,000/mm³) is also present due to platelet consumption in the microvasculature. Most patients also have altered mental status or renal insufficiency. (Choice B) Bone marrow suppression (eg, tumor infiltration) can cause chronic anemia and thrombocytopenia. However, significant reticulocytosis is uncommon because the bone marrow cannot efficiently generate cells. (Choice C) Colon cancer is a common cause of chronic anemia in older individuals who have not undergone screening colonoscopy. Reticulocytosis would be unusual (it is more common with acute, rather than chronic, blood loss anemia), and splenomegaly and thrombocytopenia are not typically present. (Choice E) Cirrhosis can cause hepatosplenomegaly with thrombocytopenia (splenic platelet trapping), as well as anemia (eg, bleeding varices, chronic inflammation). However, this patient has no risk factors for cirrhosis (eg, alcohol use, hepatitis); his elevated INR likely reflects therapeutic warfarin use rather than liver disease; and his mechanical valve makes traumatic hemolysis much more likely. Finally, because liver biopsy is an invasive procedure, noninvasive tests (eg, echocardiogram evaluating valve function) are generally performed first. Educational objective: A mechanical or severely calcified aortic valve can cause hemolytic anemia due to erythrocyte shearing. Patients also frequently have mildly low platelets due to concurrent mechanical platelet injury. An echocardiogram should be performed to assess the valvular function.

A 70-Year-Old Man Comes to the Office Due to 6