Acute and complete occlusion of the coronary artery usually results in STEMI, which usually presents with persistent ST-elevation on the ECG or as an STEMI equivalent (hyperacute T-wave changes, true posterior MI, multilead ST depression with coexistent ST-elevation in lead aVR, characteristic diagnostic criteria in the setting of LBBB). On the other hand, severely obstructive but incompletely occlusive coronary lesions usually result in NSTEMI, characterized by the absence of persistent ST elevation on ECG, but rather the presence of ST depression, T-wave inversion or other nonspecific changes. Aspirin inhibits the formation of thromboxane A2, a potent stimulator of platelet aggregation, and is the first-line therapy for AMI.30 A loading dose of 162 to 325 mg of non enteric-coated aspirin formulation should be administered as soon as possible (to be crushed or chewed to achieve rapid absorption), followed preferably by an 81-mg daily dose to minimize bleeding risk.30 34 In the ISIS-2 (Second International Study of Infarct Survival) trial,30 aspirin therapy administered within the first 24 h after acute STEMI resulted in a 23% relative risk reduction in 5-week vascular mortality (or 2.4% absolute risk reduction) in patients with STEMI. Significant reductions in the incidence of non-fatal reinfarction and stroke were also observed with aspirin.30 Clinical Recommendation(s) 2013 ACCF/AHA Guideline for the Management of Patients With ST-Elevation Myocardial Infarction12 1. Aspirin 162 to 325 mg should be given before primary PCI.33,35,36 (Class I, Level of Evidence: B) 2. Aspirin (162- to 325-mg loading dose) and clopidogrel (300-mg loading dose for patients <75 years of age, 75-mg dose for patients >75 years of age) should be administered to patients with STEMI who receive fibrinolytic therapy.30,37,38 (Class I, Level of Evidence: A) 2014 AHA/ACC Guideline for the Management of Patients With Non ST-Elevation Acute Coronary Syndromes11 1. 