A 55-year-old man was seen at our emergency department with chest discomfort. His initial ECG showed ST-segment elevation in leads I, II, III, aVF and V4-6 (Fig. 1). An ECG taken a few days after initial presentation is shown in Fig. 2. Where do you think his myocardial infarction is located? Which vessel is occluded and where? Or do you have an alternative diagnosis?