Review Question - QID 213618

A 67-year-old man presents to the emergency department with chest pain. He states that he has had worsening chest pain over the past week and now feels short of breath with even minor exertion. His temperature is 98.7°F (37.1°C), blood pressure is 159/91 mmHg, pulse is 105/min, respirations are 15/min, and oxygen saturation is 99% on room air. Physical exam is notable for a pale and frail appearing elderly man with a guaiac-positive rectal exam. An initial ECG is seen in Figure A. Initial laboratory values are notable for the following.

Hemoglobin: 8.2 g/dL
Hematocrit: 24%
Leukocyte count: 4,400/mm^3 with normal differential
Platelet count: 172,500/mm^3
Troponin: 0.20 mcg/L

The patient receives 1 unit of packed red blood cells while in the emergency department. As his transfusion is completing, the patient is complaining of flank pain and fatigue. His temperature is 102°F (38.9°C), and he appears jaundiced. Which of the following is the most likely diagnosis?