Review Question - QID 212764

A 55-year-old man presents to the emergency department for evaluation of chest pain. He states that he has had intermittent chest pain with exertion over the past week, and one hour prior to presentation he developed substernal chest pain while at rest that radiates to his jaw. He reports associated shortness of breath and nausea. He has a past medical history significant for hypertension, hyperlipidemia, and diabetes mellitus type II. His temperature is 98.6°F (37.0°C), pulse is 90, blood pressure is 110/55, respirations are 22/min and oxygen saturation is 94% on room air. On exam, he appears diaphoretic and in mild distress. Lungs are clear to auscultation, and no peripheral edema is noted. An electrocardiogram is obtained as shown in Figure A. Which of the following is the most likely explanation for this patient's electrocardiogram findings?