Downstream Versus Upstream Strategy for the Administration of P2Y12 Receptor Blockers

Inclusion Criteria: * Age ≥ 18 and \< 85 * Non ST elevated acute coronary syndrome (unstable angina, non ST elevated myocardial infarction), with an onset of symptoms during the previous 24 hours. * An initial invasive strategy is chosen (the patient is expected to undergo coronary angiography within 72 h from admission). * Subject is able to start therapy with a new P2Y12 inhibitor (prasugrel or ticagrelor) OR is on a maintenance dose of clopidogrel or ticlopidine and is able to switch to a new P2Y12 inhibitor (prasugrel or ticagrelor). * Subject is able to verbally confirm understanding of risks and benefits of dual antiplatelet therapy in coronary acute syndromes and he/she or his/her legally authorized representative provides written informed consent prior to any Clinical Investigation related procedure, as approved by the appropriate Ethics Committee. * Patient agrees to comply with follow-up evaluations. Exclusion Criteria: * Known hypersensitivity/contraindication to aspirin, clopidogrel, prasugrel, ticagrelor, heparin or bivalirudin, or sensitivity to contrast media, which can't be adequately pre-medicated. * Platelet count \<100,000 cells/mm³ or \>700,000 cells/mm³, or a white blood cell (WBC) count \<3,000 cells/mm³ within 7 days prior to index procedure. * Shock. * Have severe hepatic impairment defined as Child Pugh Class C. * Pregnant or nursing subjects and those who plan pregnancy in the period up to 3 years following screening. (Female subjects of child-bea…