Thrombocyte function in unstable angina pectoris

: In a prospective study, platelet aggregation in platelet-rich plasma after ADP stimulation (0.5, 1.0 and 10 mumol/l) and collagen (1 and 5 micrograms/ml) was measured in 36 patients with coronary heart disease, 18 with angina at rest during the eight hours preceding the time of blood sampling, and 18 patients with stable, exercise-dependent angina, matched for age and sex. In addition, c-AMP was determined, before and (as a measure of platelet adenylate cyclase activity) after stimulation of this enzyme by prostaglandin E1 (10 mumol/l for 30 sec). There were no differences between all the tested ADP and collagen concentrations with regard to platelet aggregation. c-AMP levels were also similar. Thus, in patients with unstable angina there was no evidence for generalized hyperaggregation of platelets in comparison with control subjects who had stable exercise-dependent angina.