Review Question - QID 214820

A 57-year-old man presents to the emergency department with sudden-onset chest pain. He states he was working on his car when his symptoms started. The patient has a history of hypertension and hypercholesterolemia but has not seen a primary care doctor recently to manage these conditions. He is a current smoker with a 20-pack-year history and currently takes no medications. He states that the chest pain is constant and does not radiate anywhere. His temperature is 99.3°F (37.4°C), blood pressure is 162/98 mmHg, pulse is 107/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam reveals symmetric upper extremity pulses and an uncomfortable-appearing man. A chest radiograph is performed as seen in Figure A. Which of the following is the most appropriate confirmatory test for this patient?