Coronary artery disease is the most common type of cardiovasculardisease and is the leading cause of mortality in the UK and worldwide1.It usually occurs when there is rupture of an atherosclerotic plaque leading toocclusion or narrowing of the coronary vessels that supply the muscles of theheart2. This leads to symptoms such as chest pain and tightnessthat can radiate to the arms, neck, jaw back or stomach, sweating,light-headedness, dyspnoea and nausea or vomiting3. In the 1960sthe mortality rate for myocardial infarction was estimated around 70% but todayat least 70% of patients tend to survive which reflects great improvement inthe management and prevention1,4. The general aim of treatment is reperfusion of the heartmusculature through unblocking the coronary arteries, reducing ischaemia and tomodify future risk factors; however, acute management is dependent on the typeof myocardial infarction: ST-elevation MI (STEMI) or Non-ST-elevation MI (NSTEMI)5,6.
Both types of myocardial infarctions are given an immediate loading dose of300mg aspirin and 300mg clopidogrel to reduce the size of the clot and furtherclotting with a known decrease mortality of at least 50%5,6,9. In acuteSTEMIs, patients undergo prompt revascularisation with primary percutaneouscoronary intervention (pPCI) if within 90 minutes of initial presentation,thrombolysis if >90 minutes and within 12 hours of symptom onset or acoronary artery bypass graft (CABG) dependent upon haemodynamic instability as theserevascularisation therapies can prevent or decrease damage to the myocardium7,9.In acute NSTEMIs, the initial treatment involves symptom control through painrelief, treating any life-threatening instability and observation in contrastto immediate revascularisation8,9. The current NICE guidelines regarding pharmacologicalmanagement for both types of post-myocardial infarction consists of dualantiplatelet therapy of aspirin 75mg given indefinitely in combination withP2Y12 inhibitor such as clopidogrel 75mg for up to 12 months in addition toother therapies such as an ACE inhibitor, beta-blocker and statin9. There is already a well documented benefit of dual antiplatelettherapy in acute coronary syndromes compared to aspirin alone established byCURE11, COMMIT/CCS-212 and CLARITY-TIMI 2813trials which showed an approximate 20% reduction in 1-year incidence ofcardiovascular events but a subsequent increase in bleeding risk10.However, few studies have used P2Y12 inhibitors alone and there are theories asto why aspirin may diminish the vascular benefits of P2Y12 inhibitors.