Vascular Disease USMLE Step 1 Practice Question

A 55-year-old man with a 12-year history of type 2 diabetes and hypertension presents to the emergency department with progressive dyspnea on exertion over 3 months. He reports orthopnea and paroxysmal nocturnal dyspnea for 2 weeks. Physical examination reveals blood pressure 168/98 mmHg, heart rate 108/min, respiratory rate 24/min, and oxygen saturation 91% on room air. Jugular venous pressure is elevated at 8 cm H₂O. Cardiac auscultation demonstrates an S3 gallop and bilateral basilar crackles. Lower extremity examination shows 2+ pitting edema bilaterally with intact dorsalis pedis and posterior tibial pulses. Laboratory studies show BNP 520 pg/mL (normal <100), troponin I 0.02 ng/mL (normal <0.04), and creatinine 1.4 mg/dL. Chest X-ray demonstrates pulmonary edema with normal cardiac silhouette borders. Transthoracic echocardiography reveals a dilated left ventricle (end-diastolic dimension 62 mm), global hypokinesis, and left ventricular ejection fraction of 32%. Coronary angiography shows patent coronary arteries without significant stenosis. Which of the following is the most likely diagnosis?