Significance of the Intima-Media Thickness of Carotid and Thoracic Aorta in Coronary Artery Disease in the South Indian Population

BACKGROUND: Ultrasound detected intima-media thickness (IMT) of the carotid artery and thoracic aorta are possible screening tests to assess the risk of coronary artery disease (CAD) in asymptomatic individuals. OBJECTIVE: Aim of the study was to assess the utility of carotid and aortic IMT as a predictor of CAD and to assess the extent of IMT with severity of CAD in a South Indian population. PATIENTS AND METHODS: A cross-sectional and analytical study was carried out among 40 cases, who had angiographic evidence of CAD against 30 healthy control subjects with a normal treadmill test. At plaque-free regions, the carotid IMT was evaluated by B-mode ultrasonography and thoracic aorta IMT was evaluated by trans-esophageal echocardiography (TEE). The significance of difference in means between two groups was analyzed using one-way ANOVA F-test and the significance of difference in proportions by Chi-square test. Multiple comparisons were done by Bonferroni t test. The correlation between IMT and severity of CAD was assessed by Spearman's method. RESULTS: There were 38 males and 2 females among cases with age 51.7 ± 8.3 years, and 28 males and 2 females among control subjects with age 52.2 ± 7.1 years. Increased carotid IMT was noted among 24 cases and 2 control subjects, and the association was significant for CAD [P < 0.001, Chi-square = 20.89, odds ratio (OR) = 21.00, and 95% confidence interval (CI) = 4.78-89.59]. Similarly, 19 cases and one control subject had abnormal IMT with positive correlation for CAD (P < 0.001, Chi-square = 16.39, OR = 28.24, and 95% CI = 4.06-163.21). There was no association between IMT and diabetes, hypertension, or smoking; however, IMT was significantly associated with age and dyslipidemia. Also, there was no correlation between extent of IMT and severity of CAD. CONCLUSIONS: IMT of the carotid and thoracic aorta is strongly associated with risk of CAD in a South Indian population, and may be used as a non-invasive screening tool for coronary atherosclerosis in resource-limited settings. The presence of dyslipidemia influenced IMT and may be used as a tool to follow patients on hypolipidemic drugs.