Electrocardiogram (ECG). (A) ECG on day 1 shows diffuse ST elevation in lead I, II, aVL, aVF, and V₂–V₆ with ST depression in lead V₁. (B) ECG on day 2 shows progressive ST elevation. (C) ECG on day 2 after 3 h shows significant improvement in ST-segment elevation. (D) ECG after 1-week follow-up shows ST elevation in lead V₂–V₅, the biphasic T waves in lead I, II, III, aVL, and V₄–V₆ with incomplete right bundle branch block.