ATTEST-2

In acute ischaemic stroke, recanalisation of the occluded artery is strongly associated with greater odds of recovery. Intravenous (IV) thrombolysis with the recombinant tissue plasminogen activator (rtPA) alteplase, the only medical treatment currently approved for acute ischaemic stroke, significantly increases the probability of excellent recovery (approximately 10% absolute and 60% relative increase in the likelihood of recovery without significant neurological deficit in the most recent meta-analyses). Clinical services have evolved rapidly in recent years to expedite recognition, transfer and immediate treatment of appropriate stroke patients, and 10-20% now receive IV rtPA in major UK centres. Recent randomised controlled trials (RCTs) of endovascular
clot-retrieval (thrombectomy) for stroke, predominantly used as an adjunct to IV thrombolysis, emphasise the benefit of rapid reperfusion and the potential gains from more effective recanalisation interventions. Selection of suitable patients for endovascular thrombectomy requires vascular imaging to identify appropriate target vessel occlusion, and in most recent trials additional tissue viability imaging (multiphasic collateral evaluation or perfusion imaging); even with access to advanced imaging, only around 40% of patients eligible for IV thrombolysis meet criteria. Endovascular therapy is therefore inevitably restricted to a small number of specialist centres in well-resourced healthcare systems, and the time-critical nature of stroke intervention means that the majority will not be able to access this approach, even where such infrastructure exists. There is potentially substantial benefit from better IV thrombolytic agents, an area that has until recently seen only limited clinical research, much of it focused on extending time windows.