Alan C. Cameron, MB ChB, BSc (Hons), MRCP
Antiplatelet therapy reduces the burden of recurrent vascular events in patients with non-cardioembolic ischaemic stroke or TIA and the authors present an overview of major trials. The IST and CAST studies, conducted over 20 years ago, highlight the benefits of aspirin in the acute setting and the benefits of aspirin in the longer term are demonstrated by the Antithrombotic Trialists’ Collaboration. It was later shown that aspirin and dipyridamole in combination is more effective than aspirin alone, with most data coming from the ESPS-2 and ESPRIT studies, although dipyridamole requires twice daily dosing and many patients develop headache. The PRoFESS trial shows rates of recurrent stroke are similar with clopidogrel compared to aspirin and dipyridamole, although clopidogrel has once-daily dosing and fewer patients develop headache.
The landmark CHANCE and POINT trials demonstrate that DAPT with clopidogrel and aspirin reduces the risk of stroke and vascular events in patients with high-risk TIA or minor stroke compared to aspirin alone and the benefit is confined to the early period. This may explain why longer-term trials of DAPT (MATCH, SPS3 and CHARISMA) found no benefit. The SOCRATES trial found that DAPT with ticagrelor and aspirin is not superior to aspirin in reducing vascular events, although ticagrelor shows a strong trend toward reduced stroke in the acute setting and is more efficacious in patients with large artery disease or patients already taking aspirin. The THALES trial is studying ticagrelor in this context and will help to better define the role of ticagrelor in acute stroke. Importantly, we can reduce the risk of haemorrhage associated with antiplatelet therapy by effectively managing bleeding risk factors, including blood pressure control, treatment of Helicobacter pylori infection and proton pump inhibitors for high risk patients.