There is evidence for the benefit of mechanical thrombectomy in acute ischemic stroke (AIS) from emergent large vessel occlusion (ELVO) in the anterior circulation.
- defining the criteria to evaluate and select patients with ELVO for endovascular treatment is critically important, since between 3% and 22% of patients with AIS are potentially eligible for mechanical thrombectomy (1), depending on the specific selection criteria used
- in addition to the use of intravenous (IV) thrombolysis in emergent large vessel occlusion (ELVO), endovascular therapy (EVT) has proven to be very efficient in selected acute stroke patients. The indications for EVT have progressed from the era of thrombolysis to individual patient profiling
- rigorous clinical trial data support mechanical thrombectomy in patients with intracranial and extracranial occlusions of the internal carotid artery (ICA), including tandem or isolated occlusion of the M1 and M2 segments of the MCA (middle cerebral artery)
- the American Heart Association/American Stroke Association (AHA/ASA) 2018 guidelines for the early management of patients with acute ischemic stroke
- strong recommendation to perform mechanical thrombectomy with a stent retriever within six hours of onset of symptoms without prior intravenous (iv) alteplase
- in stroke patients older than 18 years
- with non-significant pre-stroke disability (i.e., a modified Rankin scale score, mRS = 1),
- a documented causative occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA) segment M1,
- and specific clinical (i.e., National Institutes of Health Stroke Scale score >= 6)
- and radiological (i.e., Alberta stroke program early CT score, ASPECTS >= 6) features
- according to the 2018 guidelines, while iv alteplase should be administered to eligible patients even if endovascular treatments are being considered, observation after iv alteplase to assess for clinical response should be avoided in those under consideration for mechanical thrombectomy, because the risk of such observation would overwhelm its benefit
Rapid, safe and effective arterial recanalisation to restore blood flow and improve functional outcome remains the primary goal of hyperacute ischaemic stroke management
- benefit of intravenous thrombolysis with recombinant tissue-type plasminogen activator for patients with severe stroke due to large artery occlusion is limited
- since November 2014, positive randomised controlled trials of mechanical thrombectomy for large vessel occlusion in the anterior circulation have led to a revolution in the care of patients with acute ischaemic stroke
- its efficacy is unmatched by any previous therapy in stroke medicine, with a number needed to treat of less than 3 for improved functional outcome (2)
- a prospective, randomized, open-label, adaptive, international trial involving patients with stroke due to occlusion of the internal carotid artery or the first segment of the middle cerebral artery to assess endovascular thrombectomy within 24 hours after onset showed (4)
- among patients with large ischemic strokes, endovascular thrombectomy resulted in better functional outcomes than medical care but was associated with vascular complications
- cerebral hemorrhages were infrequent in both groups
Thrombectomy may be undertaken under general anaesthetic or local anaesthetic.
- common challenges are tandem occlusions of cervical internal carotid artery and intracranial vessels and fixed intracranial stenosis, which can limit endovascular access; patients often have tortuous and ectatic large vessels, with an "unfolded" aortic arch or redundant cervical carotid loops
- primary access point is the common femoral artery, but the radial or brachial approach is an alternative for those with aorto-ilialfemoral disease; the direct carotid approach has also been proposed but remains unpopular due to safety concerns
- when there is a tandem occlusion secondary to carotid disease in the neck, the interventionist has to decide which lesion to treat first and whether to deploy a carotid stent or just angioplasty any stenotic lesions
Summary points (3):
- thrombectomy for anterior circulation stroke due to proven proximal major vessel (carotid or M1) occlusion within 6 hours of stroke onset is safe and highly effective, and sets the new standard of care
- in a meta-analysis of randomised trials, the proportions of patients achieving a good (independent) functional outcome (mRS 0-2 at 90 days) were 46.0% (mechanical thrombectomy) vs 26.5% (best medical treatment); most patients also received intravenous thrombolysis
- favourable outcome from mechanical thrombectomy is strongly time dependent ("time is brain"), with the best results achieved when there is no evidence of extensive early ischaemic brain injury (e.g. ASPECTS score >5); if good recanalisation is achieved within 4.5 hours, the absolute rate of good functional outcome is 61%
- complications of endovascular procedures can follow devicerelated vessel injury (perforation, dissection, subarachnoid haemorrhage), vascular access or radiological contrast media
Endovascular thrombectomy in basilar-artery occlusion:
- in RCT (n=507;China), endovascular thrombectomy 12 hours after stroke led to better functional outcomes at 90 days vs best medical care (in 104 [46%] vs 26 [23%], aRR 2.06; 95% CI, 1.46-2.91, p<0.001), but more procedural complications & intracerebral haemorrhage (5% vs 0%) (5)
- in RCT (n=217, China), thrombectomy led to higher percentage of patients with good functional status at 90 days vs medical therapy [modified Rankin scale score 0 to 3 in 51 (46%) vs. 26 (24%); rate ratio, 1.81;95% CI,1.26-2.60; p<0.001], but more cerebral haemorrhages (6% vs 1 %) (6)
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