Acute chest pain caused by aortic dissection (AD) or acute myocardial infarction (AMI) is one of the most serious medical emergencies and requires a very quick differential diagnosis to choose the best timing for treatment. AD and AMI are often manifested with similar symptoms, making it difficult to differentially diagnose these two conditions. After supracoronary aortic repair for type A AD, small intimal flap could remain in the anastomosis area. Aortic intramural hematoma could extend to the coronary ostia causing an extrinsic compression. Intravascular ultrasound is a safe and effective methodology to distinguish an atherosclerotic plaque from an extrinsic compression. We present the case of a 68-year-old man, with a recent surgical correction of a type A AD, referred to our emergency department for an acute coronary syndrome.