Value of admission glucose to predict impaired coronary microcirculation in acute ST-elevation myocardial infarction

Abstract

Background: Acute hyperglycemia is frequently observed in non-diabetic ST-elevation myocardial infarction (STEMI) patients. It is thought to be associated with the release of stress-mediators like noradrenalin and cortisol, which antagonize insulin and promote glycogenolysis and hyperglycemia, or with the high incidence of impaired glucose tolerance among STEMI patients. Hyperglycemia recently was shown to be associated with the no-reflow phenomenon, which is mainly a manifestation of microvascular dysfunction. We recently showed that no-reflow (or not achieving TIMI 3 flow) with primary PCI for STEMI had independent prognostic value with regard tot 30-day, as well as 1-year mortality, next to admission glucose. Although no reflow in this study was an indirect measure of microvascular dysfunction, the significant association between no-reflow and increasing admission glucose and the attenuation of the effect of no-reflow by glucose concentration in multivariate analysis indicate the role of acute hyperglycemia in the pathophysiology of microvascular dysfunction. Methods: In 76 patients with a first anterior wall STEMI, baseline and minimal microvascular resistance in IRAs and non-IRAs immediately after reperfusion and at 1-week and 6-month follow-up were calculated as the ratio of mean transvascular pressure gradient to mean baseline and to adenosine-induced hyperemic blood flow velocity, respectively. Patients were divided in two groups, glucose below 11.0 mmol/L (group A) and glucose equal or higher than 11 mmol/L (group B), according to a cut-off level of the American Diabetes Association and the Euro Heart Survey. Results: Minimum microvascular resistance, defined as the ratio of mean distal pressure to average peak blood flow velocity during maximum hyperemia, showed a large variability (overall range, 0.75 to 4.89 mm Hg cm-1 s-1) and was significantly higher in group B than in group A immediately after reperfusion and at 1-week. Conclusion: In conclusion, minimal microvascular resistance is higher in anterior STEMI patients with hyperglycemia equal or above 11.0 mmol/L compared to patients with glucose leven lower than 11.0 mmol/L. Hyperglycemia in STEMI patients could prove to be an important predictor of microvacular dysfunction and obstruction.