A 48-year-old man with an unremarkable medical history presented with two hours of persistent chest tightness and heartburn. His electrocardiogram (ECG) on arrival showed 1‑ to 3‑mm upsloping ST‑segment depression at the J‑point and tall, symmetric T waves in leads II, III, and aVF. The QRS complexes were slightly widened (Fig. 1A). Initial high-sensitivity cardiac troponin I (hs-cTnI) was 0.053 μg/L (normal range 0–0.0229 μg/L) while creatine kinase-myocardial band level was normal. With atypical symptoms and nonspecific ECG changes, he was monitored in the Chest Pain Center.
