Review Question - QID 216508

A 55-year-old man presents to the emergency department with worsening dyspnea over the past 48 hours. He recently had a cold that kept him home from work for the past week. He has a past medical history of diabetes, obesity, and hypertension. He had his Achilles tendon repaired 4 weeks ago and he has been less mobile. His temperature is 99.2°F (37.3°C), blood pressure is 150/85 mmHg, pulse is 82/min, respirations are 16/min, and oxygen saturation is 100% on room air. Physical exam is notable for dyspnea provoked by walking short distances. Jugular venous distension is noted on exam. The patient’s blood pressure is 130/70 mmHg during inspiration. A bedside echocardiogram demonstrates impaired diastolic filling with normal ventricular contractility. An ECG is performed as seen in Figure A. Which of the following is the most likely diagnosis?