A n 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.Her heart rate was 74 beats/min, blood pressure was 127/72 mm Hg, and respiratory rate was 25/ min. Her temperature was 36.8°C, and oxygen saturation was 97% on ambient air. Initial examination by emergency department staff revealed an alert, well-appearing, white woman in no acute distress. No cardiac murmurs were noted, pulses were equal throughout all extremities, and there was no appreciable jugular venous distention. Pulmonary, abdominal, neurologic, and extremity examination was unrevealing. No lymphadenopathy or rash was noted. A chest radiograph revealed a normal cardiac silhouette and normal-appearing lung fields. An electrocardiogram (ECG) was obtained (Supplemental Figure, available online at http://www.mayoclinicproceedings.org), revealing ST-segment elevation in anterior, inferior, and lateral leads. Given the ST-segment elevation in the context of new-onset chest pain, the institutional ST-segment elevation myocardial infarction (STEMI) protocol was activated; she was given heparin, aspirin, and clopidogrel and taken immediately for coronary angiography.