From the Guidelines
Large vessel occlusions in the anterior circulation are amenable to thrombectomy.
Eligibility Criteria
The following criteria are used to select patients for mechanical thrombectomy:
- DAWN trial eligibility criteria: clinical imaging mismatch (a combination of NIHSS score and imaging findings on CTP or DW-MRI) for patients with large anterior circulation vessel occlusion between 6 and 24 hours from last known normal 1.
- DEFUSE 3 trial eligibility criteria: perfusion-core mismatch and maximum core size for patients with large anterior circulation occlusion 6 to 16 hours from last seen well 1.
Thrombectomy Procedure
The technical goal of the thrombectomy procedure is to achieve reperfusion to a modified Thrombolysis in Cerebral Infarction (mTICI) 2b/3 angiographic result to maximize the probability of a good functional clinical outcome 1.
Time to Reperfusion
Reduced time from symptom onset to reperfusion with endovascular therapies is highly associated with better clinical outcomes, and reperfusion to TICI grade 2b/3 should be achieved as early as possible within the therapeutic window 1.
Device Selection
Stent retrievers are indicated in preference to the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) device for mechanical thrombectomy 1.
Imaging Evaluation
For patients who otherwise meet criteria for endovascular treatment (EVT), a noninvasive intracranial vascular study is recommended during the initial imaging evaluation of the acute stroke patient, but should not delay IV alteplase if indicated 1. In patients who are potential candidates for mechanical thrombectomy, imaging of the extracranial carotid and vertebral arteries, in addition to the intracranial circulation, is reasonable to provide useful information on patient eligibility and endovascular procedural planning 1.
From the Research
Large Vessel Occlusion Amenable to Thrombectomy
- Large vessel occlusions of the anterior circulation are amenable to thrombectomy, as shown in a study of 4029 stroke patients with anterior large vessel occlusions treated with thrombectomy between January 2015 and May 2020 2.
- Thrombectomy is also beneficial for patients with large vessel occlusion strokes and minimal symptoms, with a study indicating that mechanical thrombectomy was associated with a favorable shift of NIHSS at discharge, as well as higher rates of independence at discharge and long-term follow-up 3.
- The current evidence suggests that thrombectomy is indicated in all ischemic stroke with large vessel occlusion, with recent trials demonstrating efficacy and safety in patients with large core strokes and those with basilar occlusions up to 24 hours of last known well 4.
- Patients with large vessel occlusions should be offered mechanical thrombectomy, with or without IV thrombolysis, in an extended window up to 24 hours of last known well, as it is a standard of care for a patient with an LVO 5.
- Mechanical thrombectomy plays an important role in the management of patients with mild strokes due to LVO, particularly in those not eligible for IV tPA, with a systematic review and meta-analysis showing that mechanical thrombectomy and medical therapy with IV tPA led to better 90-day functional outcome 6.
Specific Vessel Occlusions
- Terminal carotid/tandem occlusion is a risk factor for embolic complications, such as embolus to a new territory (ENT), and is associated with worse clinical outcomes 2.
- Middle cerebral-M1/M2, intracranial carotid, anterior cerebral, or basilar artery occlusions are also amenable to thrombectomy, with studies showing benefits in patients with these types of occlusions 3, 4.
- Basilar occlusions up to 24 hours of last known well are also eligible for thrombectomy, with recent trials demonstrating efficacy and safety in these patients 4.