Use of provocative testing in angina pectoris

The detection of coronary artery spasm, which can play an important role in spontaneous angina pectoris, may be particularly important with respect to therapeutic considerations. Since the documentation of spontaneous spasm is a rare occurrence, provocation of spasm under controlled conditions can facilitate the diagnosis. In our laboratory, the provocation test is carried out according to a standard protocol with the use of a bolus injection of 0.4 mg methergine ( a close congener of ergonovine). The 321 patients studied since 1976 were distributed into five groups: none of 99 patients with atypical chest pain had spasm; only one of 42 patients with typical angina pectoris of effort had spasm; spasm was induced in 48 of 104 patients with spontaneous angina pectoris, 41 of whom had Prinzmetal's variant angina with 39 of the latter demonstrating spasm; seven of 52 patients with angina both at rest and of effort displayed spasm; and two of 24 patients with myocardial infarction and normal coronary arteries were found to have methergine-induced spasm. The risk of serious complications (such as arrhythmias) is very low provided that an induced spasm is immediately relieved by intracoronary injection of nitroglycerin. Measurement of coronary sinus blood flow indicates that the mechanism is primarily that of an increase in vascular resistance due to spasm and not an increase in myocardial oxygen demands. Thus, the provocation test is useful and indicated for patients with isolated spontaneous angina pectoris, especially those with Prinzmental's variant angina, patients with angina both at rest and of effort and in patients with myocardial infarcation and normal or nearly-normal coronary arteries.