On the basis of the overall experience, the provocation of coronary artery spasm with ergonovine is thought to be a highly sensitive and specific test for coronary artery spasm in Prinzmetal's variant angina. In spite of occasional complications, in experienced hands the procedure is considered to be safe. The challenge remains to determine the value of this and other provocative interventions in assessing the role of spasm in other aspects of ischemic heart disease, particularly in patients with critical atherosclerotic lesions.