MSFinals-0171

A 65-year-old man presents to the Emergency Department with sudden onset epigastric discomfort. He has a significant past medical history of hypercholesterolaemia and type II diabetes mellitus, and he is a heavy smoker. On examination, his pulse is 30 bpm; he is hypotensive and has distended neck veins. The chest is clear to auscultation. Initial blood tests reveal an elevated troponin level, and an electrocardiogram (ECG) shows hyperacute T-waves in leads II, III and aVF.
What is the most likely diagnosis?