Effect of Extended-Release Niacin on Carotid Intima Media Thickness, Reactive Hyperemia, and Endothelial Progenitor Cell Mobilization: Insights from the Atherosclerosis Lesion Progression Intervention Using Niacin Extended Release in Saphenous Vein Grafts (ALPINE-SVG) Pilot Trial

BACKGROUND: Thirty-eight patients with intermediate (30%-60% diameter stenosis) saphenous vein graft lesions were randomized to extended-release niacin (ER-niacin) or placebo for 12 months. We sought to evaluate the impact of ER-niacin on carotid intima media thickness (CIMT), endothelial function, and endothelial progenitor cell (EPC) mobilization. METHODS: Carotid B-mode ultrasound was used to image the common and internal carotid arteries, at baseline and at 12 months after enrollment. Reactive hyperemia peripheral arterial tonometry, as assessed with EndoPAT 2000 (Itamar Medical, Inc) and EPC mobilization assessed with flow cytometry, were measured at enrollment, and at 1 and 12 months. RESULTS: The baseline clinical characteristics were similar in the two study groups. High-density lipoprotein cholesterol levels tended to increase more in the ER-niacin group (5.9 ± 8.7 mg/dL vs 1.4 ± 7.1 mg/dL; P≤.14). Between baseline and 12 months, right common carotid artery (0.96 ± 0.44 mm vs 0.70 ± 0.24 mm; P≤.04), and left common carotid artery (0.80 ± 0.30 mm vs 0.70 ± 0.20 mm; P≤.08) CIMT tended to decrease in the ER-niacin group, compared with no change in the placebo group. The change in logarithmic reactive hyperemia index between 1 month and 12 months was similar in patients receiving ER-niacin vs placebo (0.003 ± 0.12 vs -0.058 ± 0.12; P≤.39), whereas EPC mobilization increased in the ER-niacin group and decreased in the placebo group (8.65 ± 28.41 vs -5.87 ± 30.23 EPC colony forming units/mL of peripheral blood; P≤.02). CONCLUSIONS: ER-niacin did not have a significant impact on CIMT or endothelial function, but increased EPC mobilization.