Abstract 672: Association of High-Density Lipoprotein Subclass and Atherosclerotic Remodeling as Measured by Magnetic Resonance Imaging of Internal Carotid Arteries in an Elderly Population with Known Atherosclerosis
Background: Large, buoyant high density lipoprotein, also known as HDL subclass 2 (HDL2),and small, dense HDL, also known as HDL subclass 3 (HDL3) are thought to exert variable protective effects against atherosclerosis, with the former thought to be more protective for future cardiovascular risk. The aim of this study was to investigate the potential association of HDL subclass serum concentrations with internal carotid artery atherosclerotic burden defined by 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 and 6 months 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. Total HDL-C as well as HDL2 and HDL3 subclasses were determined using Vertical Auto Profile-II technique (Atherotech, Inc., Alabama).
Results: There is a statistically significant reduction in mean carotid wall volume (0.05±0.1 cm3, p=0.004), and a significant increase in total HDL-C (3.53±9 mg/dl, p=0.0087) and HDL2 levels (2.3±6.8 mg/dl, p=0.019) but not in HDL3 levels (0.98±5.9 mg/dl, p=0.25). Multivariate analysis after adjusting for age (75±4 years), gender (63 men), smoking (31 smokers), hypertension (70%), diabetes (17%) and family history of heart disease (62%), reveals that reduction in carotid wall volume is significantly related to increase in total HDL-C (0.0005 mg/dl, p=0.027) with a stronger correlation with HDL2 (0.0011 mg/dl, p=0.04) compared to HDL3 (0.0007 mg/dl, p=0.041) levels.
Conclusion: In an elderly population with known atherosclerosis on lipid lowering therapy, reduction in internal carotid wall volume is significantly and strongly associated with an increase in HDL2 subclass.