 The ticagrelor is a new blocker of the receiver P2Y12 which distinguishes itself from the clopidogrel by a superior biological efficiency. This biological property was translated in the study PLATO, having compared it with the clopidogrel in the ACS, by a reduction of the risk thrombotique. The ticagrelor is thus recommended in first intention in this indication. There seems be a variability of answer to the ticagrelor. Besides the ticagrelor infers a level of intense platelet inhibition which could explain on hemorrhagic risk which is associated with it. 