Impact of Acute Insulin Resistance on Myocardial Blush in Non- Diabetic Patients Undergoing Primary Percutaneous Coronary Intervention

Full myocardial reperfusion with restoration of coronary microcirculatory function (CMF) is a therapeutic goal in ST-segment elevation myocardial infarction (STEMI).1 Despite the success of primary percutaneous coronary intervention (pPCI), it is not achieved in 30% to 50% of patients.2,3 Insulin resistance (IR) as a part of metabolic syndrome is an important risk factor for the development of cardiac and vascular impairments and carries ominous prognosis in the setting of acute myocardial infarction.4 As a part of metabolic syndrome, IR is associated with myocardial and microvascular injury after STEMI in clinical studies. As phenomenon per se, independent of other components of metabolic syndrome, IR was related to ischemic myocardial injury after elective PCI.5

Recently, IR in the early phase of acute coronary syndrome in non-diabetic patients, assessed by the homeostatic model assessment (HOMA) index, was established as an independent predictor of in-hospital mortality. This "acute" IR is a part of the acute glycometabolic response to stress, can be transient and can occur even in patients without chronic glycometabolic derangements.6

Acute IR comprises acute hyperglycemia and/or acute hyperinsulinemia; Hyperglycemia has the prognostic relevance of hyperinsulinemia in STEMI patients and its relationship with coronary flow are less well evaluated.it also acknowledged direct acute negative cardiovascular effects as it is contributing to incomplete myocardial reperfusion and CMF impairment. The prognostic relevance of hyperinsulinemia in STEMI patients and its relationship with coronary flow are less well evaluated and acknowledged.7,8 Myocardial blush was first defined by Arnoud van't Hof etal . It is a qualitative visual assessment of the amount of contrast medium filling a territory supplied by a pericardial coronary artery.9 Myocardial blush grade is a valuable tool for assessing coronary microvasculature and myocardial perfusion in patients undergoing coronary angiography and angioplasty.

Reduced myocardial blush grade identifies patients at higher risk who need more aggressive treatment both during the procedure to improve myocardial perfusion and later for secondary prevention.10

We postulate that IR can occur in the early post pPCI period as a dynamic phenomenon even in non-diabetic patients, and be related to the development of microvascular injury. We have defined myocardial blush as a marker of coronary microvascular function, Accordingly, we have evaluated IR in relation to myocardial blush in non-diabetic STEMI patients treated by pPCI. as a primary end-point. The residual ST-segment elevation, post-TFC%; and MACE were secondary end points. The HOMA index is a simple and inexpensive marker of IR primary used in chronic states. It was recently validated against euglycemic hyperinsulinemic clamp in STEMI patients as feasible for assessing IR during myocardial infarction and therefore used in the current study.11