Thrombus composition in ischaemic stroke: histological and radiological evaluation, and implications for acute clinical management

Ischaemic stroke is one of the key causes of morbidity and mortality worldwide. Although rapid reperfusion through thrombolysis or mechanical thrombectomy is the cornerstone of acute management, the efficacy of these interventions is influenced by the underlying composition of the occluding thrombus, which varies widely. Histological examination of retrieved thrombi allows the determination of thrombus composition and may inform aetiology and secondary prevention strategies. Additionally, radiological features may provide valuable pre-treatment insights into thrombus composition to help predict treatment success. This narrative review discusses histological and radiological indicators of thrombus composition, and how this may predict success of thrombolysis and thrombectomy. Furthermore, it discusses how these insights can be applied in the diagnostic work-up of embolic stroke of undetermined source (ESUS), and the potential utility of emerging biomarkers relating to thrombus formation, in order to optimise secondary prevention strategies.