Endovascular clot retrieval is emerging as the new standard of care for large-vessel ischaemic stroke, according to Associate Professor Bruce Campbell, head of hyperacute stroke treatment at the Royal Melbourne Hospital.
“Acute ischaemic stroke is responsible for around 80% of all strokes and is a leading cause of disability and death globally…The lifetime risk for any of us having a stroke is about one in six,” said Professor Campbell who was presenting at the recent Haematology Society of Australia and New Zealand, Australian & New Zealand Society of Blood Transfusion and the Australasian Society of Thrombosis and Haemostasis combined annual congress in Melbourne.
Early intervention to restore blood flow can improve the natural history of stroke, reflecting the concept that ‘time is brain’. However the only proven strategies were intravenous thrombolysis using alteplase, and endovascular clot retrieval (thrombectomy), he told delegates.
Alteplase was first demonstrated to reduce disability after stroke in 1995.
“While further trials have solidified the evidence base and demonstrated benefit when alteplase is administered within 4.5 hours of stroke onset, even after 20 years the rates of alteplase use are suboptimal,” Professor Campbell said.
Unfortunately, a proportion of patients do not respond to alteplase for reasons including resistance of the thrombus to treatment and inability of the drug to successfully penetrate the clot.
Potentially more effective thrombolytics including tenecteplase are continuing to be explored, but others including desmoteplase have failed to show any benefit in clinical trials.
Initial studies of endovascular clot retrieval were unpromising, but the situation changed markedly in 2015 with the publication of six major studies showing benefit when newer devices were used. Most patients were pre-treated with alteplase.
A meta-analysis by Professor Campbell and his colleagues (Lancet Neurology 2015; 14: 846-54) concluded that modern thrombectomy devices achieve faster and more complete reperfusion, leading to improved clinical outcomes compared with intravenous alteplase alone.
The benefits occurred across a range of patient sub-groups, regardless of factors such as age, clinical severity of the stroke or the volume of infarcted brain tissue.
“Despite the promise of thrombectomy, thrombolysis with alteplase still has a role,” Professor Campbell said.
For example, only about one-third of patients treated with alteplase are eligible for thrombectomy, access to thrombectomy remains very limited, and the logistics of timely treatment are very challenging. In addition, there is still considerable scope to improve the implementation of alteplase therapy.
Future developments include the trialling of a ‘stroke truck’ in Victoria in 2017 – an ambulance vehicle which includes a CT scanner to allow rapid confirmation of the diagnosis and assessment of a patient’s suitability for alteplase and/or thrombectomy.