Abstract
Background
Recent trials have challenged the protective effect of HDL in atherosclerosis, implicating the need to shift the focus from total HDL concentration to its function and major subfractions. The objective of this cross-sectional study was to investigate the relation between HDL2 and HDL3 subfractions and carotid intima-media thickness (IMT), an early indicator of atherosclerosis and surrogate marker of ischemic stroke.
Methods
In NOMAS, a prospective population-based study of the incidence and risk factors of stroke, we evaluated 1041 participants (mean age 68±9 years; 38% men; 62% Hispanic, 19% black, 17% white) with available data on HDL subfractions and carotid IMT assessed by a high-resolution 2D carotid ultrasound. Carotid IMT was a composite measure of the mean IMT in all carotid artery segments. The cross-sectional association between HDL-subfractions and IMT was analyzed by multiple linear regression.
Results
We mean±SD of total HDL was 46.15±14.25 mg/dl (median = 44.00), HDL2 14.59±8.29 mg/dl (median = 13.00), HDL3 31.06±8.32 mg/dl (median = 32.00). The mean IMT was 0.90±0.08 mm. After controlling for demographics, LDL, triglycerides, and cholesterol-lowering medication, a strong association was observed between total HDL (per SD, beta=-0.008, p= 0.01), HDL2 (per SD, beta=-0.006, p=0.03) and HDL3 (per SD, beta=-0.007 p=0.01) in relation to IMT. A significant interaction was observed between diabetes (vs. non-diabetes) and HDL2 in relation to IMT (p=0.01; -0.018mm).
Conclusion
The observed strong independent inverse associations between HDL, HDL2 and HDL3 and carotid IMT. HDL2 was only significantly associated with IMT among individuals with diabetes. These observations show novel evidence for a potential role of HDL2 and HDL3 subfractions, providing the opportunity to develop novel HDL-targeted therapies for the prevention of atherosclerosis.