HDL and heart disease: NMR and CT assessment

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  • Published: Sep 1, 2016
  • Author: David Bradley
  • Channels: NMR Knowledge Base
thumbnail image: HDL and heart disease: NMR and CT assessment

HDL

Chobufo Ditah (L) and Jeremy Kark studied the effects of HDL on Israelis and Palestinians, at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine. (Photo: Hebrew University)

Nuclear magnetic resonance (NMR) spectroscopy can quantify and qualify numbers and sizes of high-density lipoprotein (HDL) particles in plasma, so-called "good cholesterol" while helical computerised tomography CT-scanning can identify the degree of calcification of coronary arteries. In a study of Israelis and Palestinians the combination has been used to look at overall burden of coronary atherosclerosis and is forcing a rethink about the role HDL has in protecting against coronary heart disease.

The presence of HDL particles in one's blood plasma has for many years been associated with a protective effect against coronary heart disease and earned HDL the name "good cholesterol". Simplistically, HDL is a carrier of the essential compound away from the heart where excess might accumulate in calcified plaques on the linings of arteries causing atherosclerosis, narrowing of the arteries and ultimately heart failure. Its "bad cholesterol" counterpart, low-density lipoprotein (LDL), that carries cholesterol towards the heart to form those tough, but waxy plaques. This has been the conventional wisdom across medicine for half a century and forms the basis of much dietary advice about avoiding eating too much fat and cholesterol-rich foods and about taking "cholesterol-lowering" medication to reduce the LDL and boost the HDL for the sake of our health.

The C factor

HDL-C is usually thought of as the most important factor of good cholesterol. But, clinical trials of drugs that boost plasma levels of HDL-C do not support a direct causal role for this material in reducing the risk of coronary heart disease. However, recent advances in the way in which lipoproteins can be separated and analysed by size and functionality means that research is accelerating towards better predictors than the conventional HDL-C. Indeed, recent research suggests that small, dense, protein-rich particles in HDL may be more protective against atherosclerosis than large, buoyant cholesterol-rich particles.

A new study from Jeremy Kark of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine, in Jerusalem undertaken by physician Chobufo Ditah, from Cameroon, as part of the Braun School's International Masters of Public Health (IMPH) program set out to explore in detail this proposition. In the research, 274 Arabs and 230 Jews living in Jerusalem were recruited and NMR and CT data recorded for plasma HDL particles and coronary artery health, respectively.

Writing in the journal Atherosclerosis the team reports a statistically significant inverse correlation between the number of HDL particles and the concentration of small and medium-sized HDL particles relative to the degree of coronary artery calcification. The results were adjusted for age, statin use, smoking, and other factors. The team saw no association between large HDL particles and coronary artery calcification in either group of people. The results also showed a weak and inconsistent association with HDL-C between male and female participants in the study.

Particle particulars

"Our findings indicate that HDL particles and the concentration of small and medium-sized HDL particles are better independent markers of coronary artery disease, as reflected by coronary artery calcification, than HDL-C, at least in this bi-ethnic population of Israelis and Palestinians," explains Ditah. "With a better understanding of HDL's complexity and a better ability to measure its components, it is now possible to move past HDL-C to more refined measures that better reflect HDL's role in coronary heart disease risk. Based on the accumulating evidence, incorporation of small and medium-sized HDL particles or HDL particles into the routine prediction of coronary heart disease risk should be considered," adds Kark.

The current findings do corroborate earlier studies with other population groups, the team says. This suggests that small dense HDL particles do have a protective effect. "The consistency of this finding in a new population of urban Arabs and Jews, using different disease outcomes and different separation methods, add more strength to those findings," Ditah points out.

Related Links

Atherosclerosis 2016, 251, 124-131: "Small and medium sized HDL particles are protectively associated with coronary calcification in a cross-sectional population-based sample"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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