A 70-year-old man suffered from angina and had a drug-eluting stent implanted in a coronary artery a few months before. He was taking aspirin, clopidogrel, atorvastatin and several other drugs. 

a) Why is he taking aspirin and clopidogrel? (7 marks) 

Percutaneous coronary intervention (PCI) with stent implantation is an important procedure in the emergency treatment of myocardial infarction (MI) where the blockage is physically removed and a stent placed in the artery to keep it open. The stent will be drug eluting, which helps to prevent reformation of blood clots within or around the stent. However there is still high risk of clot formation.

The use of dual antiplatelet therapy (DAPT) - aspirin and a P2Y12 receptor inhibitor (eg clopidogrel) is the cornerstone of the pharmacological prevention of adverse cardiovascular event post PCI + stent.

History of MI and presence of a stent increases risk of thromboembolism and another MI, which is why DAPT is recommended for at least a year post PCI.

The combination of aspirin plus a P2Y12 receptor inhibitor has better results than either one alone. The newer P2Y12 inhibitors prasugrel and ticagrelor are better than clopidogrel, although clopidogrel can be used when prasugrel or ticagrelor is not tolerated or unavailable.

Typically the DAPT regimen is up to a year, after a year the P2Y12 receptor inhibitor is reviewed and then typically it is stopped to reduce the bleeding risk, and the aspirin is continued as monotherapy indefinitely. The P2Y12 inhibitor could also be taken longer depending on the patient's clinical condition, for example if they have a higher thrombosis risk and a low bleeding risk

Please also refer to previous past paper question which is also about PCI stent and DAPT : PP June 2020 (Let me know if you can't view it)

2025 ACC/AHA Guidelines on ACS