A 58-year-old woman presented to the emergency room complaining of severe, crushing, substernal chest pain that began while she was cooking a meal at a friend’s house this morning. She tells you that she experiences this type of pain when she walks fast or does something strenuous. An electrocardiogram demonstrates some signs of ischemia. Serial cardiac enzymes reveal elevated troponin. The cardiac catheterization reveals significant stenosis of the left anterior descending coronary artery and the patient has a bare-metal coronary stent placed. After stent placement, she is placed on clopidogrel, a medication that acts to prevent thrombosis at the stent site. Of the following, which explains the mechanism of action of clopidogrel?
