Usefullness of Niacin in subjects with stable coronary heart disease [CHD], low HDL and endothelial dysfunction [ED] remains controversial. Furthermore, benefits of its prescription after an acute coronary syndrome [ACS] in pts with low HDL and ED is unknown.

The EVAN-ACS study was a double-blind randomised placebo-controlled trial aiming at the evaluation of effects of Niacin on endothelial function in subjects with low HDL (<0.4g/l) and ED who recently suffered from an ACS. Pts were screened over a 18 months period. Flow Mediated Dilation [FMD] of the brachial artery was measured in the 7 days following the ACS, and subjects with FMD<7% were randomized either to the Treatment Group [TG] (Niacin 1000mg/d) or to the Placebo Group [PG]. After 12 weeks, new measurement of FMD was performed.

75 pts with ED were randomised. Median age was 51 (45–61) and 92.6% of the pts were men. No significant baseline difference existed between the two groups for age, gender, smoking, blood pressure, plasma lipoprotein levels, CRP or FMD. After 12 weeks, FMD had significantly increased both in the TG (median absolute change: +3.6%, p<0.001) and in the PG (+2.1%, p<0.001), but the difference between the two groups was not significant (p=0.87). In the same way, CRP, LDL-C and triglycerides significantly decreased and HDL significantly increased in both groups, but these changes were not statistically different from the TG to the PG (median absolute change of CRP: −4.2 and −2.7mg/l respectively in the TG and in the PG, p = 0.63/LDL-C: −0.3 and −0.4g/l mmol/l or mg/dl, p = 0.84/triglycerides: −0.51 and –0.52g/l, p = 0.63/HDL-C: +0.07 and +0.02g/l, p = 0.09).

In this trial, conducted in subjects with ED shortly after an ACS, FMD increased both in the Niacin treated group and the placebo group, but the extent of this rise was not significantly different. Larger studies and/or higher niacin doses are required to better address this important topic.