Increased Sensitivity of Platelets from Unstable Angina Patients to Adenosine Diphosphate-Induced Aggregation.

ADP-induced platelet aggregation of normal individuals and of patients with unstable angina were studied. Abnormalities of platelet function included increased aggregability. The ADP concentration required for half-maximal aggregation was significantly lower (4.28±0.30μM) in the unstable angina patients compared with that for normal individuals (5.24±0.15μM). The results are suggestive of platelet aggregation as a useful prognostic indicator for unstable angina.