Coronary Vasomotor Responses to Bradykinin and Acetylcholine in Patients With Coronary Spastic Angina

It is unclear whether coronary endothelial function is linked to the pathogenesis of coronary spastic angina(CSA), so the present study examined the coronary vasomotor responses to acetylcholine(ACh)and bradykinin(BK)in 23 patients with CSA, 26 patients with CSA+coronary artery disease(CAD), and 21 control patients. Acetylcholine induced vasospasm of the left coronary artery in all of the patients with CSA, but not in any of the control patients. The changes in dilatation of the left coronary artery in response to bradykinin at doses of 0.2, 0.6 and 2.0μg/min in the CSA group were significantly greater than those in the other 2 groups. The ratio of epicardial coronary vasodilations induced by BK to those induced by nitroglycerin did not differ among any of the groups. Bradykinin caused a similar increase in coronary blood flow in the control group and CSA group, but had less of an effect in the CSA+CAD group. In conclusion, the vasorelaxing effect of BK was preserved not only in epicardial spasm coronary arteries induced by ACh, but also in resistance coronary arteries distal to the spasm arteries in patients with CSA. The coronary vasodilation response induced by BK may not deteriorate until coronary atherosclerosis advances in patients with CSA.