Mr. S, a 74-year-old man, is admitted to the hospital with severe substernal chest pain. In the ED, his electrocardiogram (ECG) shows the ST elevation typical of a significant myocardial infarction. In this hospital, ST-elevation myocardial infarctions are managed with emergent balloon angioplasty, and there is strong evidence linking “door-to-balloon times” to ultimate outcome. There is a delay in reaching the cardiologist on call; when he finally arrives an hour later, the cardiac catheterization lab is not prepared for the procedure, leading to another delay. The cardiologist, Dr. G, orders a dose of metoprolol, a beta-blocker. Dr. G's handwriting is difficult to read, but the pharmacist is reluctant to page the doctor, who is known for his “difficult personality.” So the pharmacist takes his best guess at the prescription and dispenses a dose of metformin, a medicine for diabetes. Ultimately, the mistake is recognized and the correct medicine is administered as the patient is being wheeled up for his angioplasty. The door-to-balloon time is 150 minutes, well above the goal of 90 minutes or less. The patient survives, but is left with a moderate amount of heart damage (ejection fraction 35%, normal 55%–70%) and mildly symptomatic heart failure.