Page 145 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Elevated glucose levels impact microvascular function in STEMI
with impaired clinical outcomes in both stable coronary artery disease and STEMI.11,29 Due to the role of insulin in establishing glucose homeostasis and altering vascular tone, we hypothesise that high insulin levels, secondary to acute insulin resistance, are the mechanism of action responsible for the increase in bAPV. Recovery of this phenomenon at follow-up likely drives recovery of normal coronary autoregulatory function. The fact that larger myocardial infarctions, as determined by troponin T levels, were associated with higher glucose levels, as well as with higher resting flow levels, suggests that the severity of the acute ischaemic event determines the magnitude of metabolic disturbance, and is thereby indirectly related to the magnitude of pan-myocardial microvascular dysfunction.
Limitations
Accurate assessment of flow velocity depends on the operator’s experience, and, furthermore, on the achievement of maximal vasodilation. The measurements in this study were performed by experienced operators. The amount of adenosine used in this study is considered sufficient.30
We only assessed reference vessel microvascular resistance in coronary arteries without angiographically significant epicardial narrowing using aortic pressure as a substitute for distal pressure.
In this study, glucose levels were only measured at admission and were not 8 repeated at 1-week and 6-month follow-up. This did not allow for exploration of
the time course of glucose levels in the period following myocardial infarction. In
addition, insulin levels were not determined at any of the time points, resulting
in the fact that the hypothesised mechanism could not be further elucidated. Subjects were excluded based on known pre-existing diabetes at the time of admission, however, information on the HbA1C levels was not available to reveal unknown pre-existing impaired glucose homeostasis. Additionally, the study population was relatively small, in particular at 6-month follow-up, and some statistical analyses may lack statistical significance because of a lack of statistical power.
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