Comparison of epicardial coronary artery tone and reactivity in Prinzmetal's variant angina and chronic stable angina pectoris

Abstract

It has been suggested that a generalized coronary vasomotion disorder is present in variant angina and that evaluation of baseline coronary artery tone may be useful for predicting the occurrence of coronary artery spasm. The vasomotor response of angiographically normal proximal and distal coronary artery segments was studied in 9 patients with atypical chest pain and normal coronary arteriograms (control group), 13 patients with active variant angina and 41 patients with chronic stable angina. Ergonovine (intravenous, 100 to 300 μg, or intracoronary, 8 to 20 μg, was administered to all 22 patients in the control and variant angina groups and to 11 of the 41 patients with chronic stable angina. All patients also received intracoronary isosorbide dinitrate (1 to 2 mg).Computerized coronary artery diameter measurement of angiographically normal segments was carried out before and after ergonovine and nitrate administration. Mean baseline intraluminal diameter of proximal and distal coronary segments was not significantly different in control patients and those with variant angina (nonspastic segments only) or coronary artery disease (proximal 2.89 ± 0.15, 2.83 ± 0.14 and 2.82 ± 0.09 mm; distal 1.60 ± 0.08, 1.63 ± 0.07 and 1.62 ± 0.06 mm, respectively). After ergonovine, proximal segments constricted by 10 ± 2%, 15 ± 3% and 11 ± 4% and distal segments by 11 ± 3%, 11 ± 2% and 14 ± 3% in control, variant angina and coronary artery disease groups, respectively (p = NS). After isosorbide dinitrate, proximal coronary segments dilated by 13 ± 2%, 11 ± 3% and 8 ± 2% (p = NS) and distal segments by 13 ± 3%, 14 ± 4% and 15 ± 2% (p = NS) in control, variant angina and coronary artery disease groups, respectively.The results of this study indicate that rest baseline coronary tone and the vasomotor response of angiographically normal coronary artery segments to ergonovine and isosorbide dinitrate are similar in patients with noncardiac chest pain, Prinzmetal's variant angina and coronary artery disease. Evaluation of basal coronary artery diameter, therefore, is not useful for predicting the occurrence or location of coronary spasm.