Provocation of coronary artery spasm.

Although a wide variety of provocative agents and physiologic maneuvers may precipitate coronary artery spasm in susceptible patients with Prinzmetal's variant angina, ergonovine maleate testing has been demonstrated to be the safest when followed in a highly structured protocol which mandates not only electrocardiographic monitoring but immediate reversal of spasm by intravenous or intracoronary nitroglycerin. The recent demonstration that calcium channel antagonists can block focal spasm attests to the remarkable clinical efficacy of these agents and suggests that a therapeutic trial with a calcium channel antagonist may preclude the necessity for provocative testing in the future.