BACKGROUND: Coronary heart disease is common in people with diabetes mellitus. Diabetes is associated with a poor prognosis in patients with an acute coronary syndrome (ACS), either with or without ST-elevation (STEMI/non-STEMI). However, more acute glycometabolic disturbances may also have a negative impact on outcome. Elevated glucose levels on admission are associated with increased mortality after ACS, irrespective of diabetic status. Whether HbA1c levels have the same prognostic significance as glucose levels in an emergency setting is unknown.
AIM: To investigate the prognostic value of admission glucose and glycosylated hemoglobin levels in acute ST elevation myocardial infarction and to assess the importance of long term blood glucose control as reflected by HbA1c in predicting outcome after acute ST elevation myocardial infarction.
METHODS: This was a prospective observational study conducted on 80 patients admitted to the Cardiology ICCU ward at Government Rajaji Hospital, Madurai with acute ST elevation myocardial infarction, irrespective of their previous diabetic status. We measured blood glucose and Hba1c at admission in these patients. The 80 patients included in this study were further stratified into five groups, based on previous history of diabetes, blood glucose levels at admission and HbA1c levels. Group 1(uncontrolled diabetes) included patients with previous history of diabetes with HbA1c > 6.5 %. Group 2(controlled diabetes) included those with previous history of diabetes with HbA1c ≤ 6.5 %. Group 3 (stress hyperglycemia) was patients with no previous history of diabetes, random blood glucose at admission ≥ 200 mg/dl and HbA1c < 6.5 %. Group 4 (undiagnosed diabetes)included those with no previous history of diabetes, random blood glucose ≥ 200 mg/dl and HbA1c ≥ 6.5%. Group 5(nondiabetic) included those with no previous history of diabetes, random blood glucose < 200 mg/dl and HbA1c < 6.5%. These patients were followed up during the hospital stay and complication rates were assessed.
RESULTS : There were 27 subjects under group 1 (uncontrolled diabetes) of which 70.4 % had complications during hospital stay and 66.7 % had a left ventricular ejection fraction (LVEF) ≤ 40 %. Among the 5 patients in group 2 (controlled diabetes), only 1 developed complication during hospital stay and all had an LVEF > 40 %. In group 3 (stress hyperglycemia), both patients developed complications and had an LVEF ≤ 40 %. There were 9 subjects in group 4 (undiagnosed diabetes),out of which 66.7 % developed complications and all had an LVEF ≤ 40 %. Group 5 included 37 patients, out of which only 8.1 % developed complications and only 13.5 % had an LVEF ≤ 40 %. Moreover, there was a significant negative correlation between HbA1c levels and left ventricular ejection fraction. There was also a significant negative correlation between admission blood glucose levels and left ventricular ejection fraction.
DISCUSSION: Our results suggest that both acute and chronic hyperglycemia are independent predictors of adverse outcome after acute ST elevation myocardial infarction. Hence, measurement of both blood glucose as well as HbA1c enables identification of these high risk groups for aggressive management
