Review Question - QID 213804

A 68-year-old man presents to the emergency department for chest pain. He has presented several times this past month for chest pain and was sent home each time after an unremarkable workup. He states that the pain occurs both at rest and with exertion and is currently present. He has a past medical history of obesity, chronic obstructive pulmonary disease (COPD), diabetes, a known left bundle branch block on ECG, and peripheral vascular disease. He recently returned on a flight after visiting his son who had 2 sick children at home. His temperature is 99.0°F (37.2°C), blood pressure is 164/94 mmHg, pulse is 100/min, respirations are 15/min, and oxygen saturation is 94% on room air. Cardiopulmonary exam is unremarkable, and the patient's abdomen is soft and non-tender. An ECG is performed as seen in Figure A. A chest radiograph is ordered and is pending. Initial laboratory studies including troponins are ordered and are pending as well. Which of the following is the most likely diagnosis?