The aim of the RAPID study is to assess the rapid onset of action of the 2 novel oral antiplatelet agents, Prasugrel and Ticagrelor, in 50 patients with STEMI undergoing PPCI with bivalirudin monotherapy.

Fifty consecutive patients with STEMI undergoing PPCI with bivalirudin (GP IIb/IIIa not allowed ) will be randomized to receive 60 mg Prasugrel loading dose (n= 25) or 180 Ticagrelor loading dose (n= 25) before PPCI. The loading dose will be performed as soon as possible in the Emergency Room or in the Cath Lab. In the case of vomit in the 2 hours after drug loading dose a new loading dose will be administered. All interventions will be performed by the femoral approach according to current standards. The use of thrombectomy before infarct-related artery stenting, of everolimus eluting stent and of closure devices will be strongly encouraged. Bivalirudin will be administered as a bolus 0.75 mg/kg followed by 1.75 mg/kg/h infusion during PCI. After PCI a reduced bivalirudin infusion of 0.25 mg/kg/h for 4 hours will be allowed. Dual antiplatelet therapy (100 mg aspirin associated with 5 or 10 mg Prasugrel or 180 mg Ticagrelor) will be recommended for 12 months.

Residual platelet reactivity will be assessed in all patients at baseline (time of loading dose), and after 2, 4, 8 and 12 hours by a point-of-care test VerifyNow bedside available in the Intensive cardiac care Unit. High residual platelet reactivity will be defined as a Platelet Reactivity Units (PRU) > 240 by VerifyNow. At the same time point, Activated Clotting Time (ACT) will be also assessed. Follow-up will be performed by outpatient visits or telephone interviews at 6 months.

Inclusion Criteria:

1. Patients presenting within 12 hours from the onset of symptoms with STEMI
2. Informed, written consent

Exclusion Criteria:

1. Age < 18 years
2. Active bleeding; bleeding diathesis; coagulopathy
3. History of gastrointestinal or genitourinary bleeding <2 months
4. Major surgery in the last 6 weeks
5. History of intracranial bleeding or structural abnormalities
6. Suspected aortic dissection
7. Any previous TIA/stroke
8. Administration in the week before the index event of clopidogrel, ticlopidine, prasugrel, ticagrelor, thrombolytics, bivalirudin, low-molecular weight heparin or fondaparinux, GPI.
9. Known relevant hematological deviations: Hb <10 g/dl, Platelet count <100x10^9/l
10. Use of coumadin derivatives within the last 7 days
11. Chronic therapy with prasugrel or ticagrelor
12. Known malignancies or other comorbid conditions with life expectancy <1 year
13. Known severe liver disease, severe renal failure
14. Known allergy to the study medications
15. Pregnancy