Microvascular Dysfunction in Acute Myocardial Infarction (AMI) and Its Relation to Outcome
Condition: ST Segment Elevation Myocardial Infarction
MeSH terms: Myocardial Infarction; ST Elevation Myocardial Infarction; Infarction
Study type: Observational

Summary: 
      The purpose of this study is first to evaluate absolute myocardial blood flow and resistance
      over time in the acute and sub-acute phase of myocardial infarction and second, to correlate
      these parameters to preservation of left ventricular function and long-term outcome.
    

Detailed description: 
      In acute myocardial infarction, early restoration of epicardial and myocardial blood flow is
      of paramount importance to limit infarct size and create optimum conditions for favorable
      long-term outcome.

      Presently, restoration of epicardial blood flow is preferably obtained by primary
      percutaneous coronary intervention (PPCI). PPCI is the treatment of choice for patients with
      acute myocardial infarction who can be admitted sufficiently fast to a hospital equipped for
      this type for treatment.

      Successful restoration of epicardial blood flow by PPCI is possible in approximately 90% of
      all patients. Nevertheless, in a number of these patients myocardial hypoperfusion persists
      due to moderate or severe microvascular dysfunction.

      The terminology "no reflow" is often used for this condition. Microvascular thromboembolism,
      spasm, or intramyocardial oedema are suggested to be responsible for this condition and
      probably all of these three phenomena play a role. Besides that, inflammatory response of the
      myocardium can be involved with neutrophil plugging of the capillaries, further compromising
      restoration of normal myocardial blood flow and function.

      It is well known that in patients in whom myocardial reperfusion is absent or limited,
      despite adequate epicardial reperfusion, prognosis is poor and more severe left ventricular
      dysfunction can be expected in comparison to those patients in whom also microvascular
      reperfusion after PPCI is restored. Therefore, it is beyond doubt that knowledge about the
      actual state of the microvasculature and myocardial (re)perfusion shortly after PPCI, is
      important from a prognostic point of view.

      Moreover, if microvascular reperfusion is still limited immediately after myocardial
      infarction, but recovers quickly in the days thereafter, this might have important
      implications for long-term prognosis.

      Lastly, knowledge about microvascular reperfusion in the acute phase can be important with
      respect to choice of adjunct mechanical or medical therapy, such as intra aortic balloon
      pumping (IABP), Gp IIb/IIIa inhibitors or continuation of nitroglycerine.

      Despite this undisputed importance of microvascular perfusion and function in the acute phase
      of myocardial infarction, its assessment has been difficult so far and has been hampered by a
      number of methodological and technical shortcomings.It should be realized in this context
      that the function of the microvasculature in general (and specifically in acute myocardial
      infarction) can be characterized by myocardial blood flow and resistance.

      Recently, the investigators have developed a new technique for measuring absolute coronary
      and myocardial blood flow and absolute and relative coronary and myocardial resistance This
      has paved the way to study microvascular function in acute myocardial infarction immediately
      after epicardial reperfusion by PPCI and in the days thereafter.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The study population consists of patients with STEMI either in our own hospital either
        referred by other hospitals or the ambulance.
      
Keywords: STEMI; absolute flow; microvascular resistance