Review Question - QID 212555

A 69-year-old woman presents to her primary care physician with her son for a 2 month history of weight loss. Over the past 2 months, she has lost at least 12 pounds. The patient denies any change in appetite but complains of diarrhea and abdominal discomfort. Additionally, she reports that her stools “smell awful,” which is embarrassing for her. Her son believes she is becoming forgetful. She forgets phone conversations and often acts surprised when he visits, even though he always confirms his visits the night before. Her medical history includes arthritis, which she admits has been getting worse, and gastroesophageal reflux disease. She takes omeprazole. She is widowed and recently retired from being a national park ranger. The patient’s temperature is 100.3°F (37.9°C), blood pressure is 107/68 mmHg, and pulse is 88/min. On physical exam, she has a new systolic ejection murmur at the left upper sternal border. Labs show a normocytic anemia. A transesophageal echocardiogram reveals a small mobile mass on the aortic valve with moderate aortic insufficiency. A colonoscopy is obtained with a small bowel biopsy. A periodic acid-Schiff stain is positive for foamy macrophages. Which of the following is the most appropriate next step in management for this patient?