Predictive value of glycosylated hemoglobin on cardiovascular outcomes in prediabetic patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Abstract

Background: Prediabetes is well known to have a substantially greater cardiovascular risk as a result of insulin resistance, dysglycemia, dyslipidemia, hypertension, endothelial dysfunction or inflammation shown as in diabetes mellitus. Previous studies demonstrated impaired glucose tolerance and/or impaired fasting glucose are strong predictors of adverse outcome in acute coronary syndrome. However, the prognostic value of glycemic controlled level, determined by glycosylated hemoglobin (HbA1c), in prediabetic patients with ACS is still undefined. The aim of this study was to demonstrate the role of HbA1c at admission on major adverse cardiac events (MACE) in prediabetic patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Methods: Using data from Korea Working Group on Myocardial Infarction (Kormi; February 2008-December 2011), this observational study included 1,536 patients who had not been diagnosed with DM before or after admission (HbA1c at admission less than 6.5%) with STEMI undergoing primary PCI. Patients were divided into two groups based on HbA1c at admission: non-diabetic (HbA1c≤5.6%, n=607, 39.5%) and pre-diabetic group (5.7%≤HbA1c≤6.4%, n=929, 60.5%). Results: One-year cumulative MACE which was defined as a composite of mortality, nonfatal MI, repeated PCI or coronary artery bypass graft, was not different between two groups (7.4% vs 9.4%, p=0.182). After multivariate logistic analysis, HbA1c was not associated with occurrence of MACE (OR 1.009, 95% CI 0.579-1.759, p=0.975). We conducted subgroup analysis and divided pre-diabetic patients into two groups by the HbA1c level of 6.0%. Both of one-year cumulative MACE (11.1% versus 7.5%) and OR for MACE were lower (OR 0.586) in patients with higher HbA1c level, but did not show any statistical significances, either. Conclusion: This study demonstrated HbA1c level at admission was not significantly associated with cardiovascular outcomes in prediabetic Korean populations with STEMI undergoing primary PCI.