Lipoprotein(a) is an important genetic risk factor for coronary artery disease in Asian Indians

Abstract

Asian Indians around the world have high rates of coronary artery disease (CAD), accompanied by a low prevalence of smoking, high cholesterol, and high blood pressure. 1 Enas E.A. Yusuf S. Mehta J. Prevalence of coronary artery disease in Asian Indians. Am J Cardiol. 1992; 70: 945-949 Abstract Full Text PDF PubMed Scopus (255) Google Scholar , 2 Enas E.A. Coronary artery epidemic in Indians a cause for alarm and call for action. J Indian Med Assoc. 2000; 98: 694-702 PubMed Google Scholar This “Asian Indian Paradox” is best explained by the synergistic effects of glucose intolerance, atherogenic dyslipidemia, and elevated levels of lipoprotein(a) [Lp(a)]. 3 Enas E.A. Dhawan J. Petkar S. Coronary artery disease in Asian Indians lessons learned so far and the role of Lp(a). Indian Heart J. 1997; 49: 25-34 PubMed Google Scholar , 4 Enas E.A. Arresting and reversing the epidemic of CAD among Indians. in: Kumar A. Current Perspectives in Cardiology. Cardiological Society of India, Chennai2000: 109-128 Google Scholar , 5 Enas E.A. Mehta J. Malignant coronary artery disease in young Asian Indians thoughts on pathogenesis, prevention and treatment. Clin Cardiol. 1995; 18: 131-135 Crossref PubMed Scopus (160) Google Scholar Lp(a) levels are higher in Asian Indians than in whites. 6 Bhatnagar D. Anand I.S. Durrington P.N. Patel D.J. Wander G.S. Mackness M.I. Creed F. Tomenson B. Chandrashekhar Y. Winterbotham M. et al. Coronary risk factors in people from the Indian subcontinent living in west London and their siblings in India. Lancet. 1995; 345: 405-409 Crossref PubMed Scopus (339) Google Scholar , 7 Chuang C.Z. Subramaniam P.N. LeGardeur B.Y. Lopez A. Risk factors for coronary artery disease and levels of lipoprotein(a) and fat-soluble antioxidant vitamins in Asian Indians of USA. Indian Heart J. 1998; 50: 285-291 PubMed Google Scholar , 8 Anand S.S. Enas E.A. Pogue J. Haffner S. Pearson T. Yusuf S. Elevated lipoprotein(a) levels in South Asians in North America. Metabolism. 1998; 47: 182-184 Abstract Full Text PDF PubMed Scopus (87) Google Scholar The Lp(a) levels in Asian Indian newborns are significantly higher than in the Chinese in Singapore, and the differences in Lp(a) levels in cord blood parallel the fourfold differences in adult CAD mortality between these 2 populations. 9 Low P.S. Heng C. Saha N. Tay J. Racial variation of cord plasma lipoprotein (a) levels in relation to coronary risk level a study in three ethnic groups in Singapore. Pediatr Res. 1996; 40: 718-722 Crossref PubMed Scopus (34) Google Scholar These data underscore the genetic determination and clinical relevance of Lp(a) in CAD among Asian Indians. Lp(a) is an independent risk factor for CAD with a relative risk of 2.7 at levels >20 mg/dl. 10 von Eckardstein A. Schulte H. Cullen P. Lipoprotein(a) further increases the risk of coronary events in men with high global cardiovascular risk. J Am Coll Cardiol. 2001; 37: 434-439 Abstract Full Text Full Text PDF PubMed Scopus (160) Google Scholar The CAD risk in patients with high Lp(a) is much greater with low high-density lipoprotein (HDL) cholesterol than with high low-density lipoprotein cholesterol. For example, the relative risk of CAD from high Lp(a) increases to 8.7 when HDL is <0.9 mmol/L versus 2.3 when LDL is >4 mmol/L. The heightened risk of CAD in Asian Indians, whose Lp(a) levels are intermediate between whites and blacks 5 Enas E.A. Mehta J. Malignant coronary artery disease in young Asian Indians thoughts on pathogenesis, prevention and treatment. Clin Cardiol. 1995; 18: 131-135 Crossref PubMed Scopus (160) Google Scholar is attributed to their low HDL, especially HDL 2b and the resulting impaired reverse cholesterol transport. 11 Superko H.R. Enas E. Kotha P. Bhat N. Impaired cholesterol transport in Asian Indians. J Am Coll Cardiol. 2001; 37 (abstr): 300A Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar Conversely, the lower rate of CAD in Blacks who have the highest level of Lp(a) is due to their high HDL level, which mitigates the pathologic effects of high Lp(a). 5 Enas E.A. Mehta J. Malignant coronary artery disease in young Asian Indians thoughts on pathogenesis, prevention and treatment. Clin Cardiol. 1995; 18: 131-135 Crossref PubMed Scopus (160) Google Scholar