Abstract 1640: High-Density Lipoprotein Particle Size and Density as Predictors of Atherosclerotic Burden as Measured by Magnetic Resonance Imaging of Internal Carotid Arteries in an Elderly Population with Known Atherosclerosis
Background: Serum concentration of high density lipoprotein (HDL-C) is inversely related to cardiovascular risk. Attention is now focused on the effect of the heterogeneity of HDL particles based on size and density, on cardiovascular risk. The aim of this study was to investigate the association of HDL subclass patterns with internal carotid artery atherosclerotic burden on MRI in an elderly population with established atherosclerosis.
Methods: The internal carotid arteries (ICA) of 82 subjects ≥65 years of age with atherosclerosis of at least moderate severity in ≥1 vascular bed were imaged on a 1.5 T MR scanner at baseline for a prospective clinical trial investigating the effects of lipid lowering therapy on carotid atherosclerosis. Five oblique slices of the thickest region of each ICA in T1-weighted (post-gadodiamide) images were obtained and vessel wall volume (cm3) was calculated. HDL particle numbers (μmoL/L) and HDL size (nm) were measured using nuclear magnetic resonance (NMR) spectroscopy (LipoScience, Inc., Raleigh N.C.) at baseline.
Results: Mean carotid wall volume at baseline was 0.40±0.1 cm3. Mean total HDL particles were 22.7± 9.3 μmol/L, while large HDL particles were 4.1±2.5 μmol/L, medium HDL particles were 0.65±1 μmol/L and small HDL particles were 17.9±7.6 μmol/L. Mean HDL size was 8.8±0.37 nm, and HDL-C was 31.6± 13.7 mg/dL. Mean ratio of small HDL/total HDL particles (0.8±0.07) was significantly (p<0.001) greater than ratio of large HDL/total HDL particles (0.17±0.08). Carotid vessel wall volume had an inverse relationship with total HDL particles (−0.0034, p=0.023), large HDL particles (−0.014, p=0.007), and small HDL particles (− 0.004, p=0.037), and HDL-C (−.0023, p=0.007). There was no relationship observed with medium HDL particles and HDL size. All associations were adjusted for age (75±4 years), gender (63 men), smoking (31 smokers), hypertension (70%), diabetes (17%) and family history of heart disease (62%).
Conclusion: In an elderly population with known atherosclerosis and low mean HDL-C levels, ICA atherosclerotic burden as measured by MRI at baseline has the strongest inverse correlation with large HDL particles.