Apport de la RMN dans l'évaluation du risque cardiovasculaire lié aux dyslipidémies

Serum level of cholesterol bound to low density lipoproteins (LDL-cholesterol) is the basic parameter used to assess lipid-related cardiovascular risk. This parameter however underestimates the number of small dense LDLs that are especially atherogenic. A new analytic proposal is based on the determination of lipoproteinic profiles obtained by NMR (Liposcience, Raleigh, NC, United-States [Am J Cardiol 90 (2002) 22i-29i]; collaboration with M.J. Chapman, Inserm U551), that allows to quantify the number of atherogenic apo B-100-containing particles. This analysis is rapid, reproducible and does not require a previous separation of lipoproteins by ultracentrifugation. NMR signals come from the terminal methyl groups of lipids located in the envelope and the core of lipoproteins. Each lipoprotein subclass produces a specific NMR signal, so that analysis of the contribution of each signal to the global signal gives the concentration of particles subclasses (nanomole per litre or micromole per litre), concentration in mass of lipid subclasses (milligram per decilitre of cholesterol or triglycerides), together with mean diameters (nanometre) of very low density lipoproteins (VLDLs), low density lipoproteins (LDLs) and high density lipoproteins (HDLs). These particles sizes [Circulation 113 (2006) 113: 1556-1563] are not totally superimposable with those obtained with more classical methodologies, especially polyacrymaide gel electrophoresis of ultracentrifugally isolated lipoproteins, especially for LDLs [Clin Chem 52 (2006) 1722-1727]. Standardization of methodologies is thus required before generalising their use in clinical biology; the NMR technology especially requires complementary studies for its application to populations with extreme lipid values, such as IIa homozygous hypercholesterolemic subjects.