Sub-Clinical Coronary Artery Disease in South Asian Immigrants: Determination of

Dodani, Sunita

Abstract

Among cardiovascular diseases, coronary artery disease (CAD) is the leading cause of death in the United States, and South Asians (people whose ancestral origin is in the Indian subcontinent i.e. India, Pakistan, Bangladesh, Nepal, Bhutan, and Sri Lanka) carry a disproportionately larger burden of CAD and metabolic syndrome. Metabolic abnormalities seem to have a synergistic effect on the development of CAD in genetically susceptible individuals. Although South Asian immigrants represent the second fastest growing Asian immigrant population in the United States, little is known regarding their increased risk for CAD. As classical risk factors may not fully explain the increased risk for CAD, the high rate of CAD among South Asians is hypothesized to be due to a combination of unique genetic predisposition and lifestyle factors. Early detection of sub-clinical CAD could prevent coronary events and substantially reduce the level of mortality and morbidity attributable to CAD in South Asian immigrants. The primary objectives of this feasibility study are to (a) assess the prevalence of sub-clinical CAD among South Asian immigrants using common carotid artery intima-media thickness (IMT) as a surrogate marker of atherosclerosis and (b) evaluate recruitment procedures, pilot reproducibility, and determine accuracy of instruments. In addition, we will identify dysfunctional HDL and Apo A-I polymorphisms among South Asian immigrants and explore the correlation with sub-clinical CAD using carotid IMT as a surrogate marker of atherosclerosis. We plan to recruit 150 South Asian immigrants living in two of the main cities in Georgia, i.e. Atlanta and Augusta, and to perform carotid artery Doppler ultrasound, and to assess several risk factors for CAD e.g. the levels of total cholesterol, LDL, HDL, Apo lipoprotein A-I (Apo A-I), homocysteine, and C- reactive proteins. We will specifically assess the level of dysfunctional HDL (pro-inflammatory HDL) and the presence of Apo A-I polymorphisms in this group. The broad, long-term goals of this research are to explore some of the unknown causes of CAD that may explain the increased excess risk of CAD in South Asian immigrants. The results of this feasibility study will assist in identifying potential issues in patient recruitment, protocol conduction, quality control and data management that will be helpful in developing larger studies (R01). In addition, determining the presence of dysfunctional HDL in South Asian immigrants will answer several questions related to the possible causes of altered HDL levels and functions. This information will not only help to stratify a high risk group, but will also be useful from a disease management point of view. The results obtained from this study will be useful to develop long-term prospective studies to assess the association of Apo A-I gene polymorphisms with CAD risk.

Public Health Relevance

South Asian immigrants are the second highest Asian immigrant population in the United State carrying high coronary artery disease (CAD) prevalence. Traditional risk factors may not fully explain this high CAD risk and gene-environment interactions play important role. Early detection of sub- clinical CAD using carotid IMT measurements as a surrogate marker of atherosclerosis will be useful to stratify into high risk group, who can benefit from preventive strategies to reduce coronary events This study will also identify some of the unknown causes of high CAD in South Asian immigrants. Dysfunctional HDL and Apo-A-1 polymorphisms play important role in CAD and information obtained from this study will not only help to stratify high risk group, but will also be useful from a disease management point of view. Furthermore, the identification of gene polymorphisms may lead to screening tests that will allow persons at risk for developing CAD to be identified early enough that prevention/intervention strategies can be implemented to prevent or ameliorate the disease process. ? ? ? ?