Post Conditioning in PCI for Acute ST Elevation Myocardial Infarction
Condition: Myocardial Infarction
MeSH terms: Myocardial Infarction; ST Elevation Myocardial Infarction; Infarction
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of this trial is to compare post-conditioning to standard angioplasty (50/50
      chance) in patients who present with an acute heart attack and are taken directly for an
      angioplasty procedure. Post conditioning is a procedure that involves balloon inflation
      followed by deflation in a series of cycles that appears to show (based on early data) that
      it can decrease the amount of damage to the heart muscle as compared to standard angioplasty
      procedures.

      Hypothesis: For Subjects undergoing direct PCI for STEMI, post conditioning with cycles of
      balloon inflation/deflation within the first minute following the re-establishment of
      coronary blood blow, will decrease the amount of irreversible myocardial damage assessed by
      delayed enhancement contrast CMR.
    

Detailed description: 
      In patients who suffer a myocardial infarction, the blood flow usually ceases due to plaque
      rupture leading to thrombus formation and vessel occlusion. The resultant entity is known as
      ST Elevation segment myocardial infarction (STEMI) and is a significant health issue in
      industrialized countries. There are over 50,000 STEMI's every year in Canada and up to 10% of
      these patients die in hospital and another 10% die within the first year after their heart
      attack. The more common problem however is not death, but irreparable damage to the left
      ventricle leading to LV dysfunction and subsequent heart failure and arrythmias.
      Re-establishing blood flow promptly by administering plasminogen activators (lytics) or
      mechanically by performing angioplasty is possible and has lowered the mortality rate
      dramatically.

      Although reperfusion is necessary, it gives rise to an entity known as ischemia-reperfusion
      where acutely re-establishing blood flow and oxygen levels of the heart has detrimental
      effects. Clinically this is manifested as no-reflow that causes subsequent damage to the left
      ventricle and decreases the beneficial affect of early reperfusion by PCI. The
      ischemia-reperfusion effect sets off a molecular cascade of events involving unfavorable
      interaction between neutrophils, platelets and endothelium, that is fairly well identified.
      Efforts to pharmacologically block this effect have not proven to be particularly effective.

      Post conditioning follows from a concept of pre-conditioning in animals that showed a
      decrease in myocardial infarct size. Pre-conditioning is not useful as it requires to be
      performed prior to the development of ischemia/injury. Post conditioning in preliminary
      studies with animals and one small study in humans have shown promising results for decrease
      in infarct size. Post conditioning is a procedure of gradual conditioning in which the artery
      is opened and closed in cycles with inflation/deflation of the culprit artery followed
      immediately by standard PCI and placement of stent.
    

Intervention name(s): Post conditioning
Intervention type(s): Procedure
Intervention description(s): 4 cycles of balloon inflation /deflation (post-conditioning) within first minute of opening up artery in primary PCI for STEMI vs usual balloon inflation sequence
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Myocardial infarction; Magnetic Resonance Imaging; Coronary Angioplasty