What are the indications for mechanical thrombectomy in a patient with acute ischemic stroke (AIS)?

From the Guidelines

Patients qualify for mechanical thrombectomy if they have an acute ischemic stroke caused by a large vessel occlusion (LVO), typically in the internal carotid artery, middle cerebral artery (M1 or M2 segments), or basilar artery, and meet specific eligibility criteria as outlined in the DAWN or DEFUSE 3 trials 1. The procedure is generally performed within 24 hours of symptom onset, though earlier treatment yields better outcomes. Key considerations for patient selection include:

• Significant neurological deficit, typically NIHSS score ≥6
• Evidence of salvageable brain tissue on imaging (CT perfusion or MRI)
• Good pre-stroke functional status (modified Rankin Scale ≤2)
• No large established infarct (ASPECTS score ≥6 on CT) While IV thrombolysis with alteplase (0.9 mg/kg, maximum 90 mg) should be administered to eligible patients within 4.5 hours of onset, mechanical thrombectomy can be performed regardless of whether the patient received IV thrombolysis. The technical goal of the thrombectomy procedure should be reperfusion to a modified Thrombolysis in Cerebral Infarction (mTICI) 2b/3 angiographic result to maximize the probability of a good functional clinical outcome 1. 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. Stent retrievers are the preferred device for mechanical thrombectomy, and the use of a proximal balloon guide catheter or a large-bore distal-access catheter may be beneficial in conjunction with stent retrievers 1. The selection of an anesthetic technique during endovascular therapy for AIS should be based on individualized assessment of patient risk factors, technical performance of the procedure, and other clinical characteristics 1.

From the Research

Qualification for Mechanical Thrombectomy

To qualify for mechanical thrombectomy, patients typically need to have:

• Acute ischemic stroke due to large vessel occlusion (LVO) in the anterior circulation 2, 3
• A baseline National Institute of Health Stroke Scale (NIHSS) score, with some studies suggesting that even patients with mild symptoms (NIHSS score ≤ 5) may benefit from mechanical thrombectomy 2, 3
• No contraindications for the procedure, such as oral anticoagulation, cancer, or recent surgery, although mechanical thrombectomy may be considered in patients with contraindications for systemic thrombolysis 4

Key Factors in Patient Selection

Key factors in selecting patients for mechanical thrombectomy include:

• Time from onset of symptoms to treatment, with most guidelines recommending treatment within 4.5 hours of symptom onset
• Location and severity of the occlusion, with proximal intracranial occlusions being more likely to benefit from mechanical thrombectomy
• Patient's overall health and medical history, including the presence of any contraindications for the procedure

Clinical Effectiveness and Safety

Mechanical thrombectomy has been shown to be effective and safe in patients with acute ischemic stroke, including those with mild symptoms 3, 5

• Clinical outcomes, such as functional independence and excellent functional outcomes, are improved with mechanical thrombectomy compared to best medical management alone 2, 3, 5
• Procedural success rates and safety outcomes, such as mortality and symptomatic intracranial hemorrhage, are similar to or better than those with best medical management alone 3, 5