Efficacy of chronic amiodarone therapy in patients with variant angina pectoris and inhibition of ergonovine coronary constriction.

In three patients with vasospastic angina pectoris, chronic amiodarone administered orally at doses of 800 and 1,000 mg/day totally suppressed spontaneous episodes of ischemic chest pain for 8 to 14 months. Before treatment, ergonovine maleate 0.2 to 0.4 mg intravenously provoked chest pain and similar ischemic ECG changes as those occurring spontaneously. During amiodarone treatment ergonovine vasoconstriction was totally or partially inhibited. In addition to calcium-blocking agents, amiodarone is another spasmolytic drug which effects smooth muscle relaxation by different mechanisms and appears to be useful for the chronic treatment and prevention of variant angina. The vasodilator property of amiodarone is achieved by both direct action and noncompetitive alpha receptor antagonism of coronary vasculature.