Mechanical recanalization of the culprit artery in acute myocardial infarction using stents provides in 2003, TIMI 3 flow restoration in more than 90% of patients. However, the prognosis of this condition remains poor, to a large degree because of microcirculatory dysfunction that is observed, in near than 20 to 40 % of patients, during or following primary percutaneous intervention. The lack of ST-segment elevation resolution after angioplasty with stenting is a marker of microcirculatory dysfunction and is associated with a poor prognosis. Routine administration with primary stenting of the platelet glycoprotein IIb/IIIa inhibitor Abciximab in acute myocardial infarction is still a matter of debate with conflicting results emerging from two major clinical studies ADMIRAL and CADILLAC. However, evidences are in favour of a benefit of this treatment especially when administrated early (in a pre-hospital manner) before percutaneous coronary intervention.Our primary purpose is to investigate the benefit of an early (i.e. pre-hospital) vs. a conventional (i.e. per-angiography) administration of Abciximab on ST-segment elevation regression at one hour after primary percutaneous angioplasty.

• Drug: Abciximab
• Drug: Abciximab placebo

• Experimental:
  • Early Abciximab bolus during prehospital transportation in ambulance 0.25 mg/Kg iv with Heparin 40 UI/kg bolus.
  • Abciximab placebo bolus and Abciximab infusion 10 µg/Kg/min after coronary angiography and before angioplasty.
• Experimental:
  • Abciximab placebo bolus during prehospital transportation in ambulance with Heparin 40 UI/kg bolus.
  • Abciximab 0.25 mg/Kg bolus after coronary angiography and before angioplasty followed by Abciximab infusion 10 µg/Kg/min.

Inclusion Criteria:

• Patients over 18 years of age eligible for randomization in the MICU
• Infarct within 6 hours from symptoms onset
• Continuous typical chest pain symptoms symptoms for more than 20 min. and-ST segment elevation of more than 2 mm in more than two leads (peripheral or precordial)
• Signed informed consent form

Exclusion Criteria:

• Ventricular conduction anomalies masking signs of ischemia (left or right bundle branch block without evidence of additional elevation), electrical left ventricular hypertrophy
• Known hypersensitivity to Abciximab or to any component of the product or to murine monoclonal antibodies.- Hemorrhagic diathesis, internal hemorrhage
• Hemorrhagic stroke within 2 years
• Ischemic stroke within the last 3 months- Intra-cranial neoplasm, intracranial malformation or arteria
• venous aneurysm
• Recent intracranial or intraspinal surgery or trauma (within two months)
• Recent within (2 months) major surgery- Known peptic ulcer or upper gastrointestinal bleeding within the previous 6 month
• Known coagulation anomaly
• Oral anti-coagulant or low molecular weight heparin treatment- Ongoing thrombolytic treatment