An 84-year-old woman presented to the emergency department with an 8-hour history of persistent substernal chest pain. The pain intensity was rated a 6 on a scale of 1 to 10, radiated to the shoulder blades, and was worse with deep breathing and lying flat. She denied dyspnea, orthopnea, palpitations, or lower-extremity edema. She had no history of cardiac disease. Her medical history was notable for well-controlled rheumatoid arthritis and hypertension. Her medications included triamterene and hydrochlorothiazide (37.5 and 25 mg/d) for hypertension and methotrexate for rheumatoid arthritis (15 mg/wk), which she had stopped taking 8 weeks earlier after recent hip surgery.