Correlation Between Severity Of Coronary Artery Disease And Glycosylated Hemoglobin levels In Patients Without History Of Diabetes Mellitus Sent For Elective Coronary Angiography

Abstract

Diabetes mellitus (DM) is a risk factor for the development of coronary heart disease (CHD), and individuals with DM have more extensive atherosclerosis, more cardiac events, and higher prevalence of silent ischemia as compared with individuals without DM. Glycated hemoglobin, assessed clinically by hemoglobin A1C, is a time integrated marker of average blood glucose concentration increasingly used in the screening and management of diabetes, and it is more closely related to the risk of complications than are single or episodic measures of glucose levels. Some studies suggest that HbA1c values in the normal range can identify persons at increased risk for CAD, stroke, and death before the diagnosis of diabetes, indicating that HbA1c is a useful marker of cardiovascular risk and death from any cause. In our study, we tried to demonstrate this relationship in non-diabetic patients by studying the correlation between HbA1c and CAD in patients undergoing coronary angiography and assessed the severity of CAD by the Gensini score. Ninty five patients (M/F=70/25) with no pat history of DM referred to our cath- lab in Cardiology department, Air force hospital for diagnostic coronary angiography between January 2014 and April 2014 were the subjects of the study. Patients were subjected to full history taking, clinical evaluation, and ECG. HBA1c, FBG, lipid profile, S.creatinine were measured using standard enzymztic methods. Diagnostic coronary artery catheterization was done to all patients to assess the severity and the extent of CAD using Gensini score. Study subjects were stratified according to the ADA recommendations 2013 upon the values of FBG and HBA1c into three groups; non-diabetic group, pre-diabetic group, discovered diabetic group. Data were coded & analyzed using IBM SPSS statistical software, P value < 0.05 was considered statistically significant. It was found that the three groups had comparable age and gender distribution, history of HTN and current smoking but there was significant difference between the three groups as regard obesity parameters, laboratory data including HBA1c, FBG, TC, TG, LDL and HDL and also there was statistically significant difference between the three groups as regard severity of CAD by means of GS. We demonstrated that the level of HbA1c is positively correlated with the severity of CAD by means of GS among the whole studied population (r = 0.57, p < 0.001), and also we found that discovered diabetic patients had higher GS than pre-diabetics and non-diabetic patients respectively (p < 0.001). And we found that HBA1c levels was positively correlated with BMI (r = 0.29, p = 0.05), TC (r = 0.50, p = < 0.001), TG (r = 0.40, p < 0.001), LDL (r = 0.59, p < 0.00), and negatively correlated with HDL (r = - 0.16 p = 0.05). And there was no significant correlation between HBA1c levels and age, gender, smoking, HTN, and family history. Also, we found the optimal cut off value of HBA1c to predict severe CAD was ≥ 5.55% with sensitivity 81% and specificity 70.3%. (AUC was 0.794, 95% CI, 0.699 – 0.889, p < 0.001). In conclusion, among the study groups, we found a significant correlation between the HbA1c level and the severity of CAD. These results were matching those of previous studies that found a significant correlation between the level of HbA1c and future cardiovascular events even in asymptomatic patients. Non-diabetic individuals with higher HbA1c values especially those categorized as pre-diabetics (high risk group) (HbA1c 5.7 to 6.4%) are at increased risk of severe CAD.