DEVELOPMENT OF MYOCARDIAL-INFARCTION IN A SPIRIN-TREATED UNSTABLE ANGINA-PECTORIS - REPEATED STUDIES OF PLATELET-AGGREGATION AND THE THROMBOXANE-PROSTACYCLIN SYSTEM

Platelet functional parameters (platelet aggregation, blood circulatin g reversibly and irreversiby aggregated platelet complexes, thromboxan e B2, 6-keto-PGF1alpha) were examined in unstable angina treated with aspirin in a daily dose of 320 mg in relation to the outcome of the di sease: Group 1, stabilization and Group 2, evolving myocardial infarct ion. Differences were found in the baseline platelet functional parame ters between the groups. The findings suggest that platelet functional parameters show a varying response to aspirin depending on the outcom e of the disease. Despite the effective inhibition of thromboxane A2 s ynthesis, aspirin was found to fail to prevent enhanced platelet aggre gatory activity in case of myocardial infarction developed during the therapy.