Author(s): Bornali Dutta1, Mahesh Neginhal2, Farhin Iqbal3
Glycosylated Haemoglobin (HbA1c) is an established marker of long-term glycaemic control in patients with diabetes mellitus (DM) and elevated HbA1c levels are associated with an increased risk for further microvascular and macrovascular disease. There have been few studies, which have shown HbA1c to be predictive of coronary artery disease and only in limited studies HbA1c has been correlated with angiographically proven CAD (coronary artery disease) using Syntax score. To aim the study to evaluate the relationship between increasing HbA1c level and severity of coronary artery disease in type 2 diabetic patients using syntax score in a cohort of proven Coronary Artery Disease (CAD) on angiography at Gauhati Medical College.
MATERIALS AND METHODS
We prospectively collected data of diabetic patients with proven CAD on angiography from June 2014 to June 2015. Patients were divided into four groups (interquartiles) according to HbA1c levels, less than 6.7%, 6.7% to 7.1%, 7.1% to 7.6% and >7.6%. Severity of coronary artery disease was assessed using syntax score and the number of coronary vessels diseased. We compared different quartiles of HbA1c with regard to syntax score and number of diseased vessels.
A total of 133 patients were included in the study. Mean age was 58.1±10.4 years. 87.2% (116) were males, 54.1% (72) were hypertensives, 21.1% (28) were smokers and 39.1% (52) were dyslipidaemic. Among diabetics, mean HbA1c was 7.1%. On analysis, we found that Coronary Artery Disease (CAD) severity by syntax score as well as number of vessels involved was significantly different among quartiles (p values <0.001 and <0.001 respectively). Mean syntax scores significantly increased with increasing HbA1c levels (syntax scores were 7, 8, 10.5, 16.58 and 25.9 in patients with HbA1c levels <6.7, 6.7-7.1, 7.1-7.6 and >7.6, respectively). In syntax subgroups (<23, 23-32 and >32), mean HbA1c values were 6.8±0.2, 7.4±0.5 and 8.0±0.4, respectively. In subgroup analysis where only chronic stable angina patients were considered, there was significant linear correlation between HbA1c and severity of CAD by syntax score (R-0.820; p<0.001) and number of vessels involved (R-0.35; p<0.001). Multivariate logistic regression analysis in diabetic population showed that HbA1c >7% was an independent predictor of syntax score >22 (OR=2.832, 95% CI 1.866-4.299; p<0.001).
From this clinical study, we can conclude that a significant correlation exists between level of HbA1c and severity of CAD by syntax score as well as number of vessels involved in 1 diabetes.