Review Question - QID 215145

A 65-year-old man presents to the emergency department with sudden-onset shortness of breath that began 1 hour ago. The patient initially presented to the hospital 10 days ago with severe chest pain and was found to have an ST-elevation myocardial infection. He underwent successful emergent cardiac catheterization with the placement of 2 drug-eluting stents and was discharged home on postoperative day 6. In addition to the recent hospitalization and catheterization, the patient has a past medical history significant for insulin-dependent type 2 diabetes mellitus and mild aortic stenosis. His medications include clopidogrel, aspirin, and atorvastatin. On arrival, his temperature is 99°F (37.2°C), blood pressure is 112/72 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 88% on room air. On exam, the patient is using accessory muscles to breathe and there are crackles throughout the bilateral lung fields. Cardiac auscultation demonstrates an apical systolic murmur that radiates to the axilla. Which of the following is the most likely cause of this patient's presentation?