Reversibility of coronary endothelial vasomotor dysfunction in idiopathic dilated cardiomyopathy: Acute effects of vitamin C

In patients with idiopathic dilated cardiomyopathy, endothelium vasomotor f unction is disturbed. Increased oxidative stress and the consecutive format ion of oxygen free radicals have been implicated as one possibility for thi s observation, suggesting that nitric oxide (NO) is inactivated by oxygen f ree radicals. We tested the hypothesis that the antioxidant vitamin C may i mprove endothelial function in idiopathic dilated cardiomyopathy. In 11 pat ients, the endothelium-dependent vasomotor response of the left anterior de scending coronary artery to intracoronary acetylcholine (ACh) infusion (1/2 x 10(-6) mol/L, 1/4 x 10(-5) mol/L; respectively) was determined before an d immediately after intravenous infusion of 3 g of vitamin C. Coronary cros s-sectional diameter was obtained by quantitative coronary angiography, ave rage peak velocity was measured by an intracoronary Doppler flow wire, and coronary blood flow (CBF) was calculated. Maximum cross-sectional diameter was determined after administration of nitroglycerin. Dose-dependent ACh sh owed a decrease in cross-sectional diameter (-5% to -7%, p <0.05) and an in crease in average peak velocity (+16% to +25%, p <0.05); the CBF was unchan ged (+1% to -2%, p = NS). After vitamin C infusion, the cross-sectional dia meter increased in a dose-dependent manner from +11% to +15%, the average p eak velocity increased from +20% to + 41% (p <0.05), and the CBF increased from +38% to + 82% (p <0.01, p <0.001, respectively). Thus, patients with i diopathic dilated cardiomyopathy had endothelial dysfunction, and administr ation of vitamin C reversed endothelium-dependent dysfunction. (C)2001 by E xcerpta Medico, Inc.