Primary hypothesis: Percentage IPA after 20uMol/ADP at 30' will be superior in the tirofiban arm (as aggregate) versus prasugrel alone arm Percentage IPA at 30' after 20uMol/ADP 90%±15 and 80%±15 in the tirofiban and prasugrel alone arm, respectively. For a power of 90% and an alpha error set at 5%, 50 patients per group have to be recruited.