Coronary Artery Disease and Coronary Risk Factors: The South Asian Paradox

Purpose : Coronary risk factors such as hypertension, diabetes and coronary artery disease (CAD) have become a major health problem in South Asians, despite low fat intake and low rates of obesity. It is a paradox that the increased risk of people of Indian origin to diabetes and CAD is not explained by conventional risk factors. It is possible that the presence of new risk factors may explain this paradox. Design : Literature-based review. Materials and Methods : Internet and Medline search with reference to new risk factors of diabetes and CAD and the review of articles in local journals. Results : Several published epidemiological and case-controlled studies are reviewed. The prevalence of hypertension (3.2%), diabetes (2.6%) and CAD (3.2%) is very low in the rural population of India. However, in urban and immigrant populations, the prevalence of hypertension (>160/95, 12-20%), diabetes (6-8%) and CAD (7-14%) is significantly higher than in the developed countries. Mean serum cholesterol (180-200 mg dl -1 ), obesity (5-8%) and dietary fat intake (25-30% en day -1 ) are paradoxically lower and do not explain the cause of increased susceptibility to CAD and diabetes. The force of lipid-related risk factors and of higher body mass index appears to be greater in people of South Asian origin owing to the presence of central obesity, insulin resistance, low high-density lipoprotein cholesterol, higher lipoprotein(a), decreased beta-cell function, in-utero undernutrition, deficiency of antioxidants and higher levels of angiotensin-converting enzyme. Conclusions : These studies support the consensus that people of South Asian origin wherever they are settled should have lower desirable limits of serum cholesterol, body mass index and dietary fat intake and should also decrease new risk factors for prevention of CAD. This finding may require modification of the existing guidelines of the International Task Force for Prevention of CAD.