Elevated Lipoprotein(a) Levels among Indian Americans
- The CADI Study found a very high prevalence of premature heart disease despite maximum modification of lifestyle. This led to the search for a genetic risk factor that is not affected by lifestyle choices.1
- Lipoprotein(a) {Lp(a)} is a risk factor for premature heart disease that is genetically determined. Its levels are not influenced by exercise and diet with the singular exception of a diet high in trans fat.2, 3
- Since stable lifelong levels are reached in infancy, the pathological effects of elevated Lp(a) start about 15 to 20 years earlier than other risk factors and explain the crucial role of Lp(a) in premature CAD (coronary artery disease).4
- Lp(a) appears to be a stronger risk factor for CAD than diabetes in young women and men.5 These particles are ten times as atherogenic as LDL (low-density lipoprotein) and has additional significant thrombogenic and antifibrinolytic properties due to its structural homology with plasminogen.6, 7
- The very first report of high Lp(a) among Asian Indians came from the US and was one of the most common risk factors in the CADI study.8 Lp(a) levels >30 mg/dL, generally considered the threshold for high risk of CAD, were found in 25% of Asian Indians compared to 17% in whites and 8% in Hispanics.8 Another Study found high Lp(a) levels >20 mg/dL in 44% of Asian Indians in the US.9
- Subsequent studies by our own group and others have repeatedly confirmed high Lp(a) levels in Asian Indians in the US,10 Canada10, India,11 Singapore,12 and the UK.13 Native Americans have the lowest levels.14, 15
- The risk of CAD from elevated Lp(a) is markedly increased in Asian Indians because of concomitant presence of high total cholesterol to HDL ratio and apo B to apo A1 ratio.14 Elevated Lp(a) plays a crucial role in malignant heart disease among young Indians worldwide.16-19
- Lp(a) levels were significantly higher among Asian Indians (36 nmol/L) than whites (29 nmol/L) (p<.0001) and Chinese (22 nmol/L) in California (using the new standardized isoform insensitive assays).20 Furthermore Asian Indians exhibited a trend towards higher CAD risk (OR 2.0) than whites (OR 1.4) but lower than Chinese (OR 4.0).20
- The population attributable risk of premature CAD from Lp(a) is 9% for the US population but appears to be significantly higher among Asian Indians, given both the higher level and risk in this population.20
Sources
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2. Enas EA. Lipoprotein(a) is an important genetic risk factor for coronary artery disease in Asian Indians. Am J Cardiol. 2001;88:201-202.
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4. Wilcken DE, Wang XL, Greenwood J, Lynch J. Lipoprotein(a) and apolipoproteins B and A-1 in children and coronary vascular events in their grandparents. The Journal of pediatrics. 1993;123(4):519-526.
5. Enas EA. Lipoprotein(a) as a determinant of coronary heart disease in young women: a stronger risk factor than diabetes? Circulation. Jan 27 1998;97(3):293-295.
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8. Enas EA, Yusuf S, Garg A, Davidson L, Thomas J, Pearson T. Lipoprotein (a) levels in Indian physicians: Comparison with Black and White physicians in the U.S.A. Indian heart journal. 1994;46 suppl:185(abstract).
9. Superko HR, Enas EA, Kotha P, Bhat NK, Garrett B. High-density lipoprotein subclass distribution in individuals of asian Indian descent: the National Asian Indian Heart Disease Project. Prev Cardiol. Spring 2005;8(2):81-86.
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15. Haffner SM, Gruber KK, Morales PA, et al. Lipoprotein(a) concentrations in Mexican Americans and non-Hispanic whites: The San Antonio Heart Study. Am J Epidemiol. 1992;136(9):1060-1068.
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19. Bhalodkar NC, EA E. Malignant Coronary Artery Disease and the Asian Indian Paradox Proceedings of the 13th International Congress on Heart Disease Conference, New Trends in Research, Diagnosis, and Treatment 2007:157-164.
20. Banerjee D, Wong EC, Shin J, Fortmann SP, Palaniappan L. Racial and Ethnic Variation in Lipoprotein (a) Levels among Asian Indian and Chinese Patients. J Lipids. 2011;2011:291954.