Endovascular clot retrieval (ECR)

Mechanical thrombectomy for acute ischaemic stroke is the endovascular retrieval of clots obstructing large intracranial vessels in acute ischaemic stroke patients and has become the treatment of choice in selected individuals with acute intracranial occlusion by thromboembolism.

History

InDespite a number of earlier trials, it was only in 2015, that multiple randomized controlled trials showed improved clinical outcome in patients with acute stroke due to large vessel occlusion undergoing thrombectomy compared to medical (conservative) treatment alone ^3-5.

IndicationsPatient selection

• acute ischaemic stroke due to large vessel occlusion in the anterior circulation within 6 hours of symptom onset
• as of 2017, several trials are underway to determine whether(e.g. DAWN ¹³ and DEFUSE3 ⁶) have shown that selected patient groups who fall outside the 6 hour time window may also benefit from thrombectomy ^6,7,1112

Contraindications

Procedure

Preprocedural evaluation

Non-contrast enhanced CT is used to exclude haemorrhage and CT angiography to determine large vessel occlusion. Alternatively, MRI and DSA may also demonstrate the occlusion. Angiographic imaging can also assess collateral vessels which contribute to predicting outcome in some settings ⁸. The role of advanced imaging such as CT perfusion to determine the infarct core and penumbra size is still uncertain ¹⁰, yet the technique is being ushered into more and more centres based on international guidelines ¹¹.

Positioning/room set up

Equipment

• stent retrievers
• aspiration devices
• balloon guiding catheter
• microcatheters

Technique

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Postprocedural care

Complications

The overall complication rate is about 15% ¹. Complications include ^2,9:

• intracranial haemorrhage (<8%)
  • parenchymal (5%)
  • subarachnoid
• emboli to new territories
• vessel perforation (1 - 5%)
• arterial dissection
• vasospasm
• vascular access site complications
  • groin haematoma (2 - 11%)
  • retroperitoneal haematoma (<6%)
• mortality

Outcomes

The technical outcome is graded using the mTICI score. Thrombectomy is a highly effective treatment for stroke with a number needed to treat (NTT) of 2.6 for an improved functional outcome. In a meta-analysis, 46% of patients treated with mechanical thrombectomy achieved functional independence (modified Rankin scale (mRS) 0–2 at 90 days) compared to 27% for best medical treatment ².