A man in his 70s with a history of hyperlipidemia presented with sudden-onset chest pain that radiated to his left arm, with associated nausea and diaphoresis. Physical examination revealed a robust senior who appeared acutely ill, in obvious pain. Vital signs revealed a blood pressure of 119/62 mm Hg; pulse, 99 beats per minute and regular; and respirations, 20 breaths per minute. Oxygen saturation was 95% on ambient air. Cardiopulmonary examination disclosed a discrete 2/6 holosystolic murmur at the apex, with otherwise unremarkable findings. Chest x-ray was clear. His electrocardiogram (ECG) on presentation is shown in the Figure.