In the 1960s, deeper investigations into the biology of platelets revealed how aspirin works to prevent clots. Platelets, in concert with some other cells, produce chemicals to signal injury and get activated. Aspirin, at low doses, blocks the key enzyme that produces these injury-sensing chemicals, thereby decreasing platelet activation and subsequent clots. As a prevention mechanism for heart attacks, aspirin may well rank among the most important medicines of the past century.
