ST-segment elevation myocardial infarction (STEMI) is the most severe form of acute coronary syndrome (ACS) aÑ–er sudden cardiac death. In USA at present, approximately 25% to 40% of all MI presentations are of STEMI. Acute myocardial infarction (MI) resulting from an occlusive thrombus is recognized on an electrocardiogram by ST-segment elevation. Нe Universal Definition of Myocardial Infarction is: a new ST elevation at the J point in at least two contiguous leads of ≥ 2 mm (0.2 mV) in men or ≥ 1.5 mm (0.15 mV) in women in leads V2–V3 and/or of ≥ 1 mm (0.1 mV) in other contiguous chest leads or the limb leads. Anterior wall contributes maximum to the ejection fraction and similarly when it is damaged it may cause maximum damage to the heart. Ischemia produced by obstruction in coronary artery, if is prolonged can produce infarction. An increase in demand is manifested by changes not only in the ST segments but a decrease in perfusion can produce a wide range of changes in the ST segments, T waves, and QRS complexes.