Pyridoxine improves endothelial function in cardiac transplant recipients

Background: Endothelial dysfunction is common in cardiac transplant recipie nts and predicts the development of transplant coronary artery disease, Hyp erhomocysteinemia is associated with endothelial dysfunction in the general population, is common in transplant recipients, and has been associated wi th transplant coronary artery disease. Thus therapy that decreases homocyst eine concentrations might also improve endothelial function and decrease th e risk of transplant coronary artery disease. Folate and pyridoxine are imp ortant cofactors in distinct aspects of homocysteine metabolism. The purpos e of this study was to determine whether folate or pyridoxine supplementati on improves endothelial function in cardiac transplant recipients. Methods and Results: This was a double-blind, randomized, placebo-controlle d trial. We assigned 31 transplant recipients to either pyridoxine (n = 11: 100 mg/day), folate (n = 1.2:5 mg/day), or placebo (n = 8) for 10 weeks. F asting and post-methionine-load (methionine 100 mg/kg orally) homocysteine concentrations were determined. Brachial artery flow-mediated dilatation wa s used as a measure of endothelial function. At follow-up, we noted no sign ificant changes in homocysteine concentrations in any of the groups. Howeve r, pyridoxine supplementation was associated with a significant improvement in endothelial function (2.8 +/- 6.7 to 6.9 +/- 6.3, p = 0.05). No signifi cant changes were seen in patients treated with folate or placebo. Conclusions: Pyridoxine, but not folate supplementation, significantly impr oves endothelial function in cardiac transplant recipients.