[Abnormal coronary response to vasomotor stimuli: analogies between variant angina and X syndrome]

The aim of this study was to evaluate the effects of hyperventilation (HV) and of ic nitroglycerin (NTG) on coronary diameters and hemodynamics in 32 patients with angina pectoris. Of these, 10 patients had stable angina and critical coronary artery disease (CAD, Group I), 12 patients with variant angina (VA) and no or minor coronary atherosclerosis (Group II), and 10 patients with angina and normal coronary arteries (syndrome X (SX), Group III). All patients underwent coronary angiography as well as right heart catheterization; measurements of left anterior descending coronary diameters (mid segment), great cardiac vein blood flow, aortic pressure and coronary resistance were performed on baseline, after HV and following NTG. HV caused coronary spasm in 4 patients with VA and significantly (p less than 0.001) reduced coronary diameters and regional blood flow both in Groups II and III, but not in Group I. NTG resulted in increased coronary diameters in all patients, however variations were greater in VA and SX (44 and 39%, respectively) than in Group I (18%; p less than 0.025). NTG induced an increase of coronary blood flow only in patients with CAD. We conclude that patients with VA and SX present a similar coronary response to vasomotor stimuli, either after HV or following NTG. Response is abnormal if compared to that of patients of group I, and it involves both epicardial and intramural coronary vessels. Thus, we suggest that SX and VA belong to a single pathogenetic entity with a spectrum of clinical manifestations.