Effects of l -Arginine Supplementation on Endothelium-Dependent Coronary Vasodilation in Patients With Angina Pectoris and Normal Coronary Arteriograms

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Abstract
Background The pathogenesis of impaired endothelium-dependent coronary vasodilation in angina pectoris and normal coronary arteriograms (microvascular angina pectoris) is not known. We examined whether supplementation with l -arginine, a precursor of endothelium-derived nitric oxide, improves endothelium-dependent coronary vasodilation in patients with microvascular angina. Methods and Results The effect of intracoronary infusion of l -arginine (50 mg/min) on acetylcholine-induced coronary vasomotion was studied in eight patients with microvascular angina and eight control subjects. The responses of the large epicardial coronary artery diameter and coronary blood flow were measured with coronary arteriography and an intracoronary Doppler catheter, respectively. Acetylcholine increased coronary blood flow with modest vasoconstriction of the large coronary artery without altering arterial pressure and heart rate. The acetylcholine-induced increases in coronary blood flow were significantly less ( P <.01) in patients than in control subjects. l -Arginine significantly augmented the coronary blood flow responses to acetylcholine in patients, but not in control subjects. l -Arginine did not alter responses of the large coronary artery in either group. Conclusions Study results suggest that l -arginine improved endothelium-dependent vasodilation of coronary microcirculation in patients with microvascular angina pectoris.