Treatment with prostacyclin of various forms of spontaneous angina pectoris not responding to placebo.

We studied the effects of prostacyclin on the frequency, duration and severity of ischemic attacks in spontaneous angina. Twenty-seven patients who did not respond to 48 hours infusion of placebo, received after a two-day observation period, 48 hours infusion of prostacyclin at an average rate of 4.0 ng/kg/min. Prostacyclin decreased number of ischemic attacks in only one of four patients with Prinzmetal angina, and was without any effect in five other patients whose attacks were associated with increase in blood pressure and heart rate. However, in 12 of 18 patients with coronary atherosclerosis, whose attacks were characterized by ST-segment depression without increase in heart rate or blood pressure, and often occurred at night, prostacyclin consistently diminished both frequency of anginal attacks and nitroglycerin consumption. This improvement lasted from 10 days to 3 months. Healing of endothelial damage by prostacyclin could explain the favorable therapeutic response in this subset of patients with spontaneous angina.