Platelet aggregation studies in patients with angina pectoris Relationships to types of angina and coronary pathoanatomy.

Platelet aggregation was studied in patients with angina pectoris in whom coronary sclerosis was found by arteriography. The subjects consisted of 20 patients with stable angina pectoris, 12 with unstable angina pectoris and 4 with variant form of angina pectoris. Fifteen healthy subjects served as controls. ADP- and collagen-induced platelet aggregations were estimated during resting conditions before and immediately after an exercise test. In patients with unstable angina pectoris, ADP-induced as well as collagen-induced platelet aggregations during resting conditions were significantly less than those in normal subjects. After exercise, however, they significantly increased. In stable angina pectoris, they did not differ from those in the control group and their responses to exercise were also not significant. In general, platelet aggregation during resting conditions was accelerated in relation to an increase in the number of coronary arteries involved. The results demonstrate that examination of platelet aggregation during resting conditions and following exercise aids in a more accurate evaluation of the types and the stages of patients with angina pectoris.