<prompt> Aspirin is used for secondary prevention of ischemic hea disease because it:-Inhibits TXA2 synthesis by plateletsInhibit prostacyclin synthesisInhibits release of EDRFInhibit synthesis of endothelins  <response>: Aggregatory substances: TXA2 ADP Inhibits aggregation: PGI2. Aspirin is Irreversible inhibitor of COX - thus preventing TXA2 formation aggregation of PLATELETS. 