Extended-release niacin reduces LDL particle number without changing total LDL cholesterol in patients with stable CAD

BackgroundThe importance of the number of circulating low-density lipoprotein (LDL) cholesterol particles, in addition to total LDL level, has been increasingly recognized. The effects of extended-release niacin (ERN) on LDL particle numbers have not been studied.ObjectiveTo evaluate ERN's effects on LDL particle numbers.MethodsFifty-four patients with stable coronary artery disease (CAD) and well-controlled LDL levels were randomly assigned to 3 months of ERN (1 g/day) or placebo in addition to their baseline medications. Lipoprotein particle number was analyzed by proton nuclear magnetic resonance spectroscopy at baseline and after 3 months.ResultsCompared to baseline, the addition of ERN had no significant effect on total LDL cholesterol levels; however, ERN decreased the number of medium and small LDL particles (P < .005). After 3 months, ERN decreased the number of medium and small LDL particles compared to placebo-treated patients (P < .05). ERN raised HDL cholesterol levels by 2.7%, significantly increased the number of large HDL particles (P < .001), and decreased the number of small HDL particles (P = .027) compared to placebo. There were no significant changes in lipid values or particle numbers in the placebo-treated patients. In patients with stable coronary artery disease and well-controlled LDL cholesterol levels, ERN reduced the number of circulating particles of the more atherogenic subtypes of LDL, despite having no effect on total LDL cholesterol levels. ERN also favorably altered the number of HDL particles.ConclusionERN-induced alterations in lipoprotein particle numbers may contribute to its anti-atherosclerotic effects, and these effects may not be evident from the standard lipid profile.