The Risk of Major Bleeding With Novel Anti-platelets: A Comparison of Ticagrelor With Clopidogrel in a Real World Population of 5000 Patients Treated for Acute Coronary Syndrome

Major bleeding after myocardial infarction portends a poor outcome. A balance is required between potency of platelet inhibition and risk of bleeding. Ticagrelor provides faster and more effective platelet inhibition than Clopidogrel. In the PLATO trial Ticagrelor reduced the incidence of cardiovascular death, myocardial infarction and stroke compared to Clopidogrel after ACS (acute coronary syndrome). Although there was no difference in overall bleeding there was more non-CABG related major bleeding with Ticagrelor. It has since been recommended, in addition to aspirin, in treatment of moderate-high risk ACS by both ESC (European Society of Cardiology) and NICE (National Institute for Clinical Excellence). There has been widespread adoption as first line therapy in UK hospitals. There remains potential concern about bleeding in a "real world" population compromising more high risk patients; particularly more elderly and female, than those in PLATO. The investigators intend to perform a large "real world" comparison of bleeding risk with Ticagrelor compared to Clopidogrel in a UK ACS population. The investigators plan an observational cohort study of patients presenting with ACS at 5 district general hospitals in Merseyside and Cheshire. The investigators will collect data retrospectively on 2500 patients treated with Clopidogrel prior to the guideline change and 2500 treated with Ticagrelor thereafter. The primary end point will be incidence of BARC 3-5 (Bleeding Academic Research Consortium) and PLATO major bleeding.

Inclusion criteria

• Patient commenced on clopidogrel for ACS prior to change of ACS guidelines, or tiacgrelor for same indication afterwards.

Exclusion criteria

• Patient already taking the drug in question (clopidogrel or ticagrelor) prior to the ACS event
• Patients under 18 years of age
• Patients in whom the drug is stopped during the same hospital admission due to clinical judgement dictating that it is no longer indicated (this does not apply to patients in whom a bleeding event is the precipitant for stopping the drug)