Alpha-adrenergic blockade in vasotonic angina: lack of efficacy of specific alpha 1-receptor blockade with prazosin
RM Robertson,
YD Bernard,
RK Carr,
and
D Robertson
To clarify the possible role of the alpha 1-adrenergic receptor in angina due to coronary artery spasm, a double-blind, randomized, placebo-controlled trial of the specific alpha 1-antagonist, prazosin, was performed. Six patients with vasotonic angina were studied, with efficacy measured by continuous electrocardiographic recording and the tabulation of chest pain and nitroglycerin usage. Despite plasma prazosin levels adequate to produce a six-fold shift in the response to phenylephrine, there was no significant difference in the number of ischemic episodes while taking prazosin (9.8 +/- 6.3 episodes/24 h) compared with placebo (10.5 +/- 6.9). There was also no difference in the length of ischemic episodes, which averaged 231 +/- 35 seconds with placebo and 231 +/- 33 with prazosin. Chest pain and nitroglycerin usage were not altered by prazosin. These data suggest that coronary artery spasm is not primarily caused by an effect on or an abnormality of the coronary vascular alpha 1-receptor.
