NACB - Scientific Shorts
NACB - Scientific Shorts (formerly NACB Blog)
By William E. Winter, MD
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 In the November issue of AACC's Strategies publication, Mr. Bill Malone writes about "Improving Cardiovascular Risk Prediction" through the use of new lipid markers. The article's summary of the National Lipid Association's (NLA) expert panel (J Clin Lipidol 2011;5:338-367) is that for patients at low risk for cardiovascular disease (CVD), no new markers should be used for screening, CRP was recommended for those patients at intermediate risk of CVD (per current NCEP ATP III recommendations), HDL or LDL subfractions are not recommended for any patients, and "For Lp-PLA2, Apo B, LDL-P, and Lp(a), the recommendations are mixed, depending on the risk level and whether patients are on-treatment or not."

I think this is a very balanced and appropriate summary of current recommendations. What I'd like to write about is that atherosclerosis is a multifactorial disease and that we should not expect that every patient with CVD need have a lipid disorder.

The multifactorial nature of CVD is forgotten when we read about studies that emphasize that half of people with myocardial infarctions have lipids in the desirable range. Indeed, this should not be surprising. There are many other "acquired" factors that can damage the endothelium initiating atherosclerosis such as hypertension, smoking and diabetes.

At one time it was widely believed that only 50% of people with CVD had traditional risk factors. Now we know that this is not correct. In fact, more than 80% to 90% of people with CVD have one or more traditional risk factors. Below is a passage taken from my chapter on lipids that was originally published in Bill Clarke's book entitled Contemporary Practice in Clinical Chemistry, 2nd Edition

". . . . traditional risk factors are observed in the vast majority of people who suffer from ASCVD (arteriosclerotic CVD). Philip Greenland and colleagues [1] reviewed 3 prospective cohort studies: the Chicago Heart Association Detection Project in Industry with 35,642 participants, the Multiple Risk Factor Intervention Trial with 347,978 screenees and the Framingham Heart Study with 3295 participants. Clinical follow-up of the subjects lasted 21 to 30 years. They evaluated the following risk factors for fatal coronary heart disease (CHD) and non-fatal myocardial infarction: total cholesterol of => 240 mg/dL, systolic blood pressure =>140 mm Hg, diastolic blood pressure => 90 mm Hg, cigarette smoking and diabetes. Among the 3 studies, 87-100% of subjects with fatal CHD (n = 20,995) had one or more risk factors for ASCVD. For nonfatal myocardial infarction, 92% of men had =>1 risk factor and 87% of women has =>1 risk factor. In a companion piece published in the same issue of JAMA [2], Khot et al. reviewed 14 international randomized clinical trials of CHD with a total of 122,458 subjects. Smoking, diabetes, hyperlipidemia, and hypertension were studied with reference to the development of CHD. 80.6% of men and 84.6% of women had one of more of the ASCVD risk factors."
 
From a public health viewpoint, we likely need more attention to the basics of CVD prevention: healthy diet, exercise, achievement of ideal or near-ideal weight and screening, diagnosis and treatment of diabetes, hypertension and dyslipidemia. For our "metabolic" population, these basic approaches are likely to have the best outcomes at the lowest costs to the individual and society. This requires that the individual be responsible for his or her own health. For parents, they need to create a healthy environment for their children.
 

 

 

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Posted by
On 1/14/2012

As the author of this particular blog, I'd like to know "Is LDL or HDL subfractionation requested by your clinicians?" At our institution, we receive few (if any) requests for LDL or HDL subfractionation over the course of a year. The issues here concerning LDL subfractionation are lack of reproducible classification of subfractionation when comparing methods [1], lack of available drugs that selectively lower dense LDL levels, and lack of outcome studies that show lowering dense LDL specifically lowers risk for CVD independent of lowering other LDL subfractions. As well, dense LDL is most commonly elevated in the setting of the metabolic syndrome where pharmacotherapy, if indicated, would most likely be targeting elevations in VLDL (e.g., elevated triglycerides) and depressions in HDL-C. Fortunately, those drugs used to lower VLDL also lower LDL. [1] Ensign W, Hill N, Heward CB. Disparate LDL phenotypic classification among 4 different methods assessing LDL particle characteristics. Clin Chem. 2006 Sep;52(9):1722-7.

Posted by
On 1/13/2012

As always, a very balanced and well thought out commentary. This comment was approved by the NACBLOG editorial board. Please remember to add your name and affiliation!

About the Author
William E. Winter, MD
William E. Winter, MD 
 

References

1. Greenland P, Knoll MD, Stamler J, et al. Major Risk Factors as Antecedents of Fatal and Nonfatal Coronary Heart Disease Events. JAMA. 2003;290:891-7.

2. Khot UN, Khot MB, Bajzer CT, Sapp SK, Ohman EM, Brener SJ, Ellis SG, Lincoff AM, Topol EJ.Prevalence of Conventional Risk Factors in Patients With Coronary Heart Disease. JAMA. 2003;290:898-904.