To determine the safety and efficacy of 2 vs 4 cycles of postconditioning method during primary PCI and direct stenting in acute MI, and to compared to primary PCI and direct stenting without the postconditioning.

Sample size: 45 subjects

Site Locations: Sheba medical center

Patients: Patients presenting with an acute MI with onset of symptoms  6h, and planned to undergo primary PCI will be included. The target lesion should be located in the proximal or middle segment of a main native coronary artery, and should be suitable for percutaneous intervention.

Primary Objective: To determine the safety and efficacy of 2 vs 4 cycles of postconditioning method during primary PCI and direct stenting in acute MI, and to compared to primary PCI and direct stenting without the postconditioning.

Primary Endpoint:

• ST segment resolution.
• Segmental wall motion score, resolution of edema and wall thickness by echocardiography.
• Infarct size estimation by cardiac enzymes and cardiac MRI.

Secondary endpoints:

• Composite endpoint of Major Adverse Cardiac Events (MACE) at 30 and 90 days

Methods:

• ECG at baseline, immediately after procedure, 90 and 180 minutes after the procedure and 6-24 hours after intervention.
• Core laboratory angiography measurements of TIMI flow, corrected TIMI Frame count, myocardial blush score and left ventricular angiography.
• Myocardial enzymes measurements: every 4 hours in the first 24 hours and every 6 hours in the following 48 hours.
• Left ventricular ejection fraction and wall motion score determined by echocardiography.
• Cardiac MRI estimation of infarct size. • Clinical follow-up at 30 and 90 days post procedure.

Follow-up:

• Follow up at 30 days: Clinical.
• Clinical Follow up & Cardiac MRI at 90 days.

Inclusion Criteria:

• Patient is > 21 years of age and provides informed consent.
• Evidence of AMI as indicated by signs and symptoms. Diagnosis of ST-segment elevation AMI will be based on chest pain for >30 minutes and ST-segment elevation of >1mV in 2 limb lead or >2mV in 2 anterior leads contiguous leads on the 12-lead ECG.
• Eligible to undergo primary PCI.
• Symptom duration is < 6 hours prior to primary PCI.
• Angiographic: The target lesion in the infarct related artery (IRA) should be occluded (TIMI).
• Angiographic: The target lesion in the proximal or middle segment of a native major coronary artery (LAD, RCA or dominant CX).
• Angiographic: The target lesion should be suitable for PTCA or stenting.
• Angiographic: The IRA occlusion will be successfully opened by stenting with TIMI 2-3

Exclusion Criteria:

• Unwillingness to participate.
• Prior Acute MI
• Cardiac arrest or Killip score III-IV
• Women with known pregnancy.
• Active significant bleeding.
• Known allergy for aspirin, ticlopidine and clopidogrel, or heparin.
• Chronic renal failure with creatinine > 2 mg/dl
• Other medical illness associated with limited life expectancy or that may cause the patient to be non-compliant with the protocol.
• Current participation in other trials using investigational drugs or devices.
• Contraindications to MRI including: arrythmias, cardiac pacer, brain aneurysm clips, cochlear implants, nerve stimulator.