Infarct size is a major determinant of prognosis after Acute Myocardial Infarction (AMI). The investigators recently reported that cyclosporine A, when administered immediately prior to percutaneous coronary intervention (PCI), can significantly reduce infarct size in STEMI (ST Elevation acute Myocardial Infarction) patients. The objective of the present study is to determine whether cyclosporine can improve STEMI patient clinical outcome. Nine-hundred and seventy two patients with ST elevation MI will be entered into a multicentre, randomized, placebo-controlled, double-blinded study. They will receive one single injection of cyclosporine A (CicloMulsion, verum) or an equivalent volume of placebo prior to reperfusion therapy by PCI. The incidence of the combined endpoint (mortality, hospitalization for heart failure, left ventricular (LV) remodeling) will be assessed at one year and three years after treatment.

Inclusion Criteria:

Eligibility criteria (for screening before hospital admission):

1. All (male and female) patients, aged over 18, without any legal protection measure,

2. Having a health coverage,

3. Presenting within 12 hours of the onset of chest pain,

4. Who have ST segment elevation ≥0.2 mV in two contiguous leads,

5. For whom the clinical decision was made to treat with percutaneous coronary intervention (PCI).

   And (further inclusion criteria to be confirmed by the admission coronary-angiography):

6. The culprit coronary artery has to be the LAD

7. The LAD artery has to be occluded (TIMI flow grade 0-1) at the time of admission coronary angiography.

8. Preliminary oral informed consent followed by signed informed consent as soon as possible.

Patients undergoing either primary PCI or rescue PCI are eligible for the study. Patients with previous AMI, PCI or coronary artery bypass surgery (CABG) are eligible for the study.

Exclusion Criteria:

1. Patients with loss of consciousness or confused
2. Patients with cardiogenic shock
3. Patients with the left circumflex or the right coronary artery (RCA) as the culprit artery, or with evidence of coronary collaterals to the risk region
4. Patients with an opened (TIMI > 1) LAD coronary artery at admission on initial (admission) coronary angiography
5. Patients with 5.2. known hypersensitivity to cyclosporine 5.3. known hypersensitivity to egg, peanut or Soya-bean proteins 5.4. known renal insufficiency (either known creatinin clearance < 30 ml/min/1.73m² or current medical care for severe renal insufficiency) 5.5. known liver insufficiency 5.6. uncontrolled (treated or untreated) hypertension (> 180/110 mmHg)
6. Patients treated with any compound containing Hypericum perforatum (St.-John's-worth) or Stiripentol or Aliskiren or Bosentan or Rosuvastatine
7. Female patients currently pregnant or women of childbearing age who were not using contraception (oral diagnosis).
8. Patients with any disorder associated with immunological dysfunction more recently than 6 months prior to presentation 8.2. cancer, lymphoma 8.3. known positive serology for HIV, or hepatitis