Endovascular clot retrieval (ECR)

Endovascular clot retrieval (ECR) is increasingly performed in patients with presenting with emergent large vessel occlusion (ELVO), especially those with a large ischaemic penumbra that is likely to go to ischaemic stroke. To be successful, careful patient selection and dedicated training and equipment are necessary. 

History

Despite 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.  As a result of these trials, endovascular clot retrieval has now become the standard of care for acute strokes. 

Patient selection

• acute ischaemic stroke due to large vessel occlusion in the anterior circulation within 6 hours of symptom onset
• several trials (e.g. DAWN ¹³ and DEFUSE3 ⁶) have shown that selected patient groups who fall outside the 6 hour time window also benefit from thrombectomy ¹²

Contraindications

• intracranial haemorrhage on initial non-contrast CT
• large infarct core with no significant penumbra (i.e. no salvageable brain)
• various patient factors (e.g. pre-morbid functional status, advanced directives, etc...) 

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 although this is less common due to difficulty with timely access to MRI in most institutions.

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.