Co-Hosts: Ryan Muir, Tess Fitzpatrick, Houman Khosravani
Key Terms: Endovascular therapy (EVT), Mechanical Thrombectomy, Large Vessel Occlusion, CT-Perfusion, Perfusion Mismatch
Summary:
In this episode the hosts review the past 15 years of evidence for the role of endovascular therapy for acute ischemic stroke and trace its evolution to present day guidelines for the acute treatment of stroke.
What is endovascular therapy?
What were the early trials of EVT – what did we learn from them?
These early trials facilitated the development of later trials done between December 2010 and December 2014, that outlined a reduction in mortality and stroke disability (as measured by theModified Rankin Scale (MRS) at 90 days).
These trials were summarized in a meta-analysis performed by theHERMESin collaboration in 2016.
In the HERMES pooled analysis thenumber needed to treat with EVT was 2.6 persons to reduce MRS by 1 point.
One trial was done later also favoured EVT, but was not included in the HERMES meta-analysis - theTHRACE trial
These trials led to the2015 AHA/ASA focused update and recommendation that endovascular treatment should be offered to patients with acute ischemic stroke when:
Pre-stroke mRS score 0 to 1
Even in those patients receiving IV r-tPA within 4.5 hours of onset
Causative occlusion of ICA or proximal MCA (M1)
NIHSS score of ≥6 and ASPECTS ≥6
Presenting within 6-hrs of symptom onset
While the above trials demonstrated benefit of endovascular therapy performed within 6 hours of symptom onset (although REVASCAT demonstrated a benefit within 8 hours) in the context of acute ischemic stroke, two trials were recently published that demonstrate benefit beyond6 hours and up to 24 hours in select patients.
oDAWN
As a result of DAWN and DEFUSE 3, the2019 AHA/ASA Guidelines now suggest:
Within 0 – 6 hours of symptom onset:Direct aspiration thrombectomy as a first pass or mechanical thrombectomy with a stent retriever should be done if the following criteria are met: (i) prestroke MRS of 0 – 1 (ii) causative occlusion of the internal carotid artery or MCA segment 1 (M1) (iii) age >18 years (4) NIHSS ≥ 6
Within 6 – 24 hours of symptom onset
In selected patients with acute ischemic stroke within 6 – 16 hours of last known normal who have a large vessel occlusion in the anterior circulation and meet other DAWN or DEFUSE 3 eligibility criteria, mechanical thrombectomyis recommended
In selected patients with acute ischemic stroke within 6 – 24 hours of last known normal who have a large vessel occlusion in the anterior circulation and meet other DAWN eligibility criteria, mechanical thrombectomy is reasonable