Acute ischemic stroke has been the focus of intense research in which the landscape has changed dramatically. From the previous paradigm of no acute treatment with heavy emphasis of antiplatlets and statins for thrombic or thromboembolic strokes and/or anticoagulation for cardioembolic strokes, to the introduction of intravenous alteplase in 1996 when given within 3 hours, to an extension of intravenous alteplase to 4.5 hours in 2010.
In most stroke programs including our growing endovascular and stroke program at Lutheran GEneral Hospital, the outcomes of endovascular thrombectomy that neurologists have seen have suggested an overall positive trend in selected patients whom have a proximal artery occlusion and either small or no ischemic stroke changes on CT (based on ASPECTS) in regards to functional independence. However, the data has not shown this observation to be valid until now.
I will touch on two of the more recent studies: the ESCAPE trial and EXTEND-IA trial.
ESCAPE trial -
Eligibility - Acute ischemic stroke (AIS) within 12 hrs, >/= 18 yrs of age, NIHSS > 6, functionally independent before stroke, CTA showing proximal vessel occlusion in anterior circulation, no large infarct core on initial head CT and had good collateral flow. Controls received IV tPA only.
Main objective - mRS score @ 90 days
Outcomes - after 90 days - odds ratio of improving by 1 point on mRS was 2.6 for endovascular treatment (EVT) patients, achieving mRS score of functional independence of 0-2 @ 90 days was 53% in EVT and 29% in control. Mortality @ 90 days - 10.4% EVT, 19% control. Symptomatic hemorrhage in 3.6% of EVT patients, 2.7% control. Cerebral ischemia TIMI scores of 2b or 3 (excellent reperfusion) noted in 72.4% of EVT patients.
EXTEND-IA trial -
Eligibility - Acute ischemic stroke (AIS) within 6 hrs, >/= 18 yrs of age, CTA showing proximal vessel occlusion in anterior circulation, no large no large infarct core on perfusion imaging, mismatch between infarct and perfusion volume. Controls received IV tPA only.
Main objectives - % reduction in perfusion lesion volume between initial imaging and imaging at 24 hrs (reperfusion), early neurological recovery, mRS score @ 90 days, death due to any cause
Outcomes - Significant increase in successful reperfusion - median 100% in EVT patients versus 37% in controls. mRS score @ 90 days have odds ratio of 2 of reducing mRS score by 1. 71% had acheived functional independence (mRS score 0-2) in EVT patients vs 40% in controls. TIMI cerebral ischemia scores of 2b and 3 achieved in 86% of patients. Finally and interestingly, 0% of EVT group suffered symptomatic ICH vs 6% in controls.
These studies show that individuals with an acute ischemic strokes with proximal anterior circulation occlusion (in my institution within 6 hours) would benefit from endovascular treatment. There is an important caveat however, both studies had different inclusion criteria. EXTEND-IA covered perfusion, ESCAPE was based on perusal of initial CT brain. Some aspects of the studies may not be relevant to your practice, especially if you do not have perfusion imaging available. Also, angiography results also play a role, patients with poor collateral flow will not have such rosy outcomes as noted in EXTEND-IA, ESCAPE and even the MR CLEAN trial which was published in 2014. These trials were based on highly selected patients and thus, should be considered when evaluating whether a patient would be a good candidate for endovascular thrombectomy.
