Review Question - QID 214906

A 76-year-old woman is evaluated in the inpatient unit 3 days after recent myocardial infarction (MI). She reports mild shortness of breath on exertion but denies any other symptoms. She has a history of hypertension, hyperlipidemia, and diabetes mellitus. Her medications consist of lisinopril, metoprolol, atorvastatin, metformin, aspirin, and clopidogrel. She received percutaneous coronary intervention 3 days ago. She does not smoke cigarettes, drinks alcohol socially, and denies illicit drug use. Her temperature is 36.8°C (98.2°F), blood pressure is 136/85 mmHg, pulse is 86/min, and respirations are 12/min. Physical exam is notable for a new harsh holosystolic murmur best heard along the lower left sternal border. Additionally, right heart catheterization reveals a right ventricular pressure of 35/10 mmHg, oxygen saturation of 70% in the right atrium, and oxygen saturation of 88% in the right ventricle. Which of the following is the most likely diagnosis?