Acute coronary syndrome is a term used to describe a range of conditions associated with sudden, reduced blood flow to the heart. One such condition is a heart attack (myocardial infarction) — when cell dAcute coronary syndrome is a medical term used to describe problems that occur when there isn't enough blood flow to the heart. eath results in damaged or destroyed heart tissue. Acute coronary syndrome (ACS) refers to a spectrum of clinical presentations ranging from those for ST-segment elevation myocardial infarction (STEMI) to presentations found in non–ST-segment elevation myocardial infarction (NSTEMI) or in unstable angina. It is almost always associated with rupture of an atherosclerotic plaque and partial or complete thrombosis of the infarct-related artery. It refers to a range of conditions in which too little blood can reach the heart, for example, because of a blockage. Acute coronary syndrome is a term for a group of conditions that suddenly stop or severely reduce blood from flowing to the heart. Acute coronary syndrome (ACS) secondary to a coronary embolism is an unusual occurrence, yet an important consideration given the difficult diagnosis. Acute coronary syndromes encompass a spectrum of conditions which include unstable angina, and myocardial infarction with or without ST-segment elevation.