Platelet aggregation in variant angina: its relation to plasma catecholamines.

We concurrently measured plasma catecholamine levels and platelet aggregation in patients with variant angina, effort angina and old myocardial infarction. Platelet aggregability was lower in variant angina than in effort angina and old myocardial infarction. Plasma concentrations of epinephrine and norepinephrine in the variant angina group showed higher values than those in the effort angina group and the old myocardial infarction group. Moreover, there was a statistically significant negative correlation between plasma catecholamine concentration and ADP-induced platelet aggregation. These findings suggest that the lower platelet aggregation is related to the higher concentration of plasma catecholamine in variant angina.