Effect of acetylcholine on the highly stenotic coronary artery: Difference between the constrictor response of the infarct-related coronary artery and that of the noninfarct-related artery

AbstractTo examine the constrictor response of the infarct-related stenotic coronary artery in comparison with that of noninfarct-related stenotic arteries, acetylcholine in maximal doses of 100 μg for the left and 50 μg for the right coronary artery was injected into the 16 infarct-related coronary arteries of 16 patients with previous myocardial infarction (group 1) and into 19 stenotic coronary arteries of 16 patients with stable angina without myocardial infarction (group 2). Acetylcholine's effects on lumen diameter and area were quantitatively analyzed at the stenotic segment and its proximal segment without significant stenosis.Acetylcholine decreased lumen diameter and area at the stenotic segments from 0.72 ± 0.18 to 0.18 ± 0.33 mm and from 0.45 ± 0.22 to 0.10 ± 0.22 mm2, respectively, in group 1 (both p < 0.01) and from 0.75 ± 0.22 to 0.49 ± 0.30 mm and 0.48 ± 0.29 to 0.26 ± 0.23 mm2, respectively, in group 2 (both p < 0.01). Acetylcholine decreased the diameter and area at the proximal segment from 2.71 ± 0.75 to 2.38 ± 0.6 mm and from 6.18 ± 3.4 to 4.71 ± 2.23 mm2, respectively, in group 1 (both p < 0.01) and from 2.31 ± 0.67 to 1.95 ± 0.59 mm and from 4.5 ± 2.97 to 3.22 ± 1.96 mm2, respectively, in group 2 (both p < 0.01). The changes in diameter and area at the stenotic segment in group 1 were significantly greater than those in group 2 (both p < 0.01); there were no significant differences between groups in the changes at the proximal segment. Total or subtotal occlusion of the stenotic artery was induced in 11 (69%) patients in group 1 compared with 4 (21%) patients in group 2 (p < 0.01 group 1 vs. group 2).It is concluded that the constrictor response to acetylcholine of the stenotic segment of the infarct-related coronary artery is enhanced as compared with that of noninfarct-related arteries