Lipids, Lipoproteins, and Apolipoproteins as Risk Markers of Myocardial Infarction

Disclosure: Consultations: None since May 2008. Prior to May 2008, Abbott, Merck, Schering-Plough, Unilever (donated to AHA). Honorariums for educational, not promotional, activities: Abbott, Merck, Pfizer (an educational website), Unilever.
Pub Date: Thursday, March 12, 2009
Authors: Neil J. Stone, MD, FAHA 
Article: Lipids, Lipoproteins, and Apolipoproteins as Risk Markers of Myocardial Infarction in 52 Countries (the INTERHEART Study): A Case-Control Study

McQueen MJ, Hawken S, Wang X, Ounpuu S, Sniderman A, Probstfield J, Steyn K, Sanderson JE, Hasani M, Volkova E, Kazmi K, Yusuf S, ,  Lipids, lipoproteins, and apolipoproteins as risk markers of myocardial infarction in 52 countries (the INTERHEART study): a case-control study.,  Lancet,  372 (9634) 224-33.
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This was a standardized case-control study of acute myocardial infarction (MI) in 12,461 cases and 14,637 age-matched (+/- 5 years) and sex-matched controls in 52 countries. Using nonfasting blood samples, the authors sought to compare whether cholesterol or apoprotein markers better predict coronary heart disease.

Measurement of a nonfasting apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio was superior to any of the cholesterol ratios for estimation of the risk of acute MI in all ethnic groups in this study.

While the ApoB/A1 ratio performed well in this large-scale study, issues of availability, standardization, and physician education/patient understanding with what these numbers mean need to be resolved. Although apoprotein measurements are now standardized and ApoB is the major apoprotein of all atherogenic lipoproteins, these measurements are not as available as low-density lipoprotein (LDL) cholesterol (LDL-C) and non-high-density lipoprotein (HDL)-C (total cholesterol - HDL-C) measurements. The latter measurement is readily available in physician offices which can measure cholesterol and HDL-C at the point of care. The National Cholesterol Education Program Adult Treatment Panel III (ATP III) pointed out that because non-HDL and ApoB are highly correlated, non-HDL-C represents an acceptable surrogate marker for ApoB in routine clinical practice. In the population-based, prospective cohort experience in Framingham, Mass., the overall performance of the ApoB:ApoA-1 ratio for prediction of congenital heart disease (CHD) was comparable to that of traditional lipid ratios. It did not offer incremental utility over total cholesterol:HDL-C. The authors felt that these data do not support measurement of ApoB or ApoA-1 in clinical practice when total cholesterol and HDL-C measurements are available. Sadly, major laboratories still do not routinely include non-HDL-C as part of the lipid panel report, so physicians should ask for this and include non-HDL-C in their flow charts. Because lipid experts continue to use ApoB for diagnosis and as a guide to optimal lipid therapy, especially in those with diabetes and/or insulin resistance or low HDL-C, evaluation of the use of ApoB measurements in routine practice deserves continued and ongoing review.

-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association. --