Variable response of the peripheral circulation to acetylcholine in patients with coronary artery disease

The purpose of this study was to assess endothelium-mediated vasodilation in the peripheral circulation of patients with coronary artery disease who are free from hypertension, hypercholesterolemia, diabetes mellitus, and congestive heart failure. The vascular response of the superficial femoral artery to an endothelium-dependent (i.e., acetylcholine 10−7, 10−6, and 10−5 mol/L) and to an endothelium-independent (i.e., nitroglycerin 10−8 and 10−6 mol/L) dilator was compared in 13 patients with angiographically documented coronary artery disease and in 7 patients with normal coronary angiograms. Vascular response was assessed by Doppler ultrasonography. Whereas the vascular responses to nitroglycerin in patients with abnormal and normal findings on coronary angiograms were similar, the responses to acetylcholine were clearly different. The ratio of mean blood flow velocity (± SD) measured during administration of acetylcholine 10−6 mol/L and mannitol was significantly lower in patients with abnormal versus normal results of coronary angiography (1.15 ± 0.35 vs 2.20 ± 1.06; p < 0.05). The vascular response to acetylcholine 10−5 mol/L in patients with an abnormal finding on their coronary angiogram was highly variable when compared with that in patients with normal results. Thus, in patients with angiographically proven coronary artery disease, the response of the peripheral circulation to acetylcholine is characterized by a great variability and a reduced sensitivity, when compared with that in patients with normal findings on coronary angiography.