Association of extremely high levels of high-density lipoprotein cholesterol with endothelial dysfunction in men

BACKGROUND: It is not clear whether a high level of high-density lipoprotein cholesterol (HDL-C) is associated with lower risk of atherosclerosis. It is likely that HDL-C is a double-edged sword for atherosclerosis. OBJECTIVE: The purpose of this study was to evaluate the relationship between HDL-C levels and endothelial function in men. METHODS: This was a cross-sectional study. We evaluated flow-mediated vasodilation (FMD) and serum levels of HDL-C in 5842 men aged 18 to 92 years who were not receiving lipid-lowering therapy. All participants were divided into four groups by HDL-C level: low HDL-C (<40 mg/dL), moderate HDL-C (40-59 mg/dL), high HDL-C (60-79 md/dL), and extremely high HDL-C (≥80 mg/dL). We were not able to evaluate the amount of alcohol intake because there was limited information on the amount of alcohol drinking in our database. RESULTS: FMD values were significantly smaller in the low group and the extremely high group than in the high group (P = .001 and P = .016, respectively). There was no significant difference in FMD between the low group and the extremely high group. Multiple logistic regression analysis revealed that extremely high HDL-C, but not low HDL-C, was independently associated with the lowest quartile of FMD (odds ratio: 1.39, 95% confidence interval: 1.09-1.77; P = .009). CONCLUSIONS: An extremely high level of HDL-C in men (8.1% of this population) was associated with a significant reduction in FMD.