Introduction

  • mechanical recanalization (thrombectomy/endovascular treatment) is an essential therapeutic method for large vessel occlusions (LVO)
  • the goal is to achieve rapid and complete recanalizationTICI 2b/3 (AHA/ASA 2019 I/A)
  • mechanical treatment is performed after preceding IVT (bridging therapy) or as primary (direct) thrombectomy (dMT) if IVT is contraindicated (ESO-ESMINT 2019)
  • start treatment ASAP! → see here
  • intravenous thrombolysis (IVT) should not be omitted before thrombectomy in eligible patients   IVT+MT vs. IVT alone (ESMINT, 2019)
    • thrombolysis facilitates the effect of MT
      • the MR-CLEAN NoIV, SWIFT-DIRECT, and DIRECT-SAFE  trials did not show the superiority of dMT
      • meta-analyses show better outcomes with combination therapy compared to dMT [Vidale, 2020] [Katsanos, 2019] [Wang, 2020]
      • IVT led to peripheral thrombus migration in 54% of patients in the INTERRSeCT trial, of which 27% had significant thrombus shift and was associated with a better outcome, and 27% had a moderate shift with no effect on the outcome  [Ohara, 2020]
      • sometimes, thrombus displacement more peripherally may not lead to clinical improvement and may make subsequent endovascular procedures difficult or impossible [Flint, 2020]
    • thrombolysis should not significantly delay the start of MT → do not wait for its effect and immediately transfer the patient to the center performing MT (ESO-ESMINT 2019, AHA/ASA 2019)
    • the RACECAT trial should answer whether it is better to thrombolyse the patients in the Stroke Center and then transport them to the Comprehensive Stroke Center (“drip and ship”) or transport the patient directly to the CSC (“mothership”)
  • ESO guidelines 2021 prefer TNK 0.25mg/kg over t-PA 0.9 mg/kg in patients scheduled for thrombectomy

Time ≤ 6 hours from onset of symptoms

  • the effectiveness of MT performed ≤6h from the onset of stroke was demonstrated by studies using retrievers (published in 2015)
  • trials showed high efficacy (recanalization rate up to 90%) + low risk of sICH (MR CLEAN 6%, ESCAPE 3.6%, EXTEND IA 0%, REVASCAT 1.9%)
  • the absolute effect of treatment in achieving patient independence is 14-31%!
  • stent retrievers and/or PENUMBRA are used (according to the ASTER and COMPASS trials, the efficacy is the same as for retrievers)  Outcome comparison of ADAPT vs. retriever (ESO 2019)

Time > 6 hours from onset of symptoms

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Overview of mechanical recanalization methods

  • stent retrievers
    • SOLITAIRE, TREVO, BONNNET, ERIC
    • 4th.generation – EMBOTRAP, SOLITAIRE PLATINUM
  • distal aspiration catheters (DAC)
    • PENUMBRA
    • PENUMBRA JET7, SOFIA PLUS
Methods rarely used or obsolete :

  • proximal thrombectomy – disruption of the proximal part of the thrombus with/without aspiration (EKOS, EPAR)
  • distal thrombectomy – pulling the distal portion of the thrombus (MERCI)
  • stenting – compression of the thrombus to the vessel wall
  • mechanical disruption of the thrombus with a microcatheter (e.g., during IAT)
Solitaire
  • at first, the stent is deployed over the entire extent of the thrombus (for 3-10 minutes)
  • then extraction of the stent with thrombus follows
    • during extraction, proximal balloon occlusion of the artery and simultaneous aspiration to achieve retrograde flow are recommended
  • permanent stent unbundling is not currently allowed
  • the method can be combined with local administration of tPA (IAT)
  • approved by FDA in 3/2012 to treat acute stroke, based on the results of the SWIFT trial
    • the Solitaire device achieved better angiographic, safety, and clinical outcomes than did the Merci Retrieval System
  • a meta-analysis of 6 European studies included 141 patients (mean NIHSS 18) with intracranial vessel occlusion and confirmed good results [Dávalos, 2012]
    • recanalization (TICI ≥ 2b) was achieved in 86% of cases; in 55%, a favorable clinical outcome was achieved
  • other positive trials (EXTEND-IA, ESCAPE a SWIFT PRIME ) were published in 2015
  • Solitaire X is a new generation revascularization device with a unique parametric design   Solitaire X
Solitaire
SOLITAIRE - successful recanalization of M1 occlusion
Trevo
  • approved by FDA in 8/2012 based on the findings of the TREVO-2 trial
    • 60 patients; TICI ≥ 2a was achieved in 91.7%, TICI 2b and 3 in 78.3%
    • mRS 0-2 in 55%, sICH 5%
TREVO
TREVO retriever used to recanalize M2 occlusion
Penumbra
  • proximal thrombectomy device
  • it combines mechanical disruption of the thrombus with aspiration of the fragments
  • thanks to aspiration, decreased risk of distal embolization can be expected compared to mechanical disruption with conventional catheters
  • in the Penumbra Pivotal Stroke Trial with 125 patients, recanalization (TIMI 2-3) was achieved in 81.6%, but in the group with complete or partial recanalization, only 37% had mRS 0-1. [Stroke 2009]
  • the Penumbra system was also tested in the IMS-III
Penumbra
Recanalization of M2 segment with PENUMBRA
Tigertriever
  • approved by FDA in 3/2021 → see here
  • comparable efficacy and safety with other retrievers [Gupta, 2021]
    • n=160
    • the primary endpoint (TICI 2b-3): 84.6%; the first pass successful reperfusion rate was 57.8%
    • after all interventions, successful reperfusion (modified Thrombolysis in Cerebral Ischemia score ≥2b) was achieved in 95.7%, and excellent reperfusion (modified Thrombolysis in Cerebral Ischemia score 2c-3) in 71.8%.
    • the primary safety composite endpoint rate of mortality and symptomatic intracranial hemorrhage was 18.1%, compared with the 30.4% performance goal and the 20.4% historical rate 
    • good clinical outcome was achieved in 58% at 90 days
  • TIGERTRIEVER13 can be used in vessels as small as 1 mm in width and up to a maximum of 2.5 mm, where larger retrievers would be appropriate

→ see more about TIGERTRIEVER

Tigertriever
Eric
  • The Embolus Retriever with Interlinked Cages (ERIC) is one of the latest devices
  • it has several architectural features that are supposed to enhance its ability to remove clots and prevent distal emboli
  • in a large multicenter registry, the ERIC device provided equivalent angiographic and clinical results to conventional retrievers  (Ducroux, 2020)
Bonnet
  • design similar to Solitaire device
Bonnet
Recanalization of M1 segment with the Bonnet retriever
EKOS

EKOS Endovascular System – Ultrasound-Assisted Catheter-Directed Thrombolysis

  • EKOS was the first interventional device indicated to treat pulmonary embolism
  • EKOS fragments the thrombus using low-energy intravascular ultrasound (1.7Mh US probe) introduced directly into the thrombus area + facilitates penetration of the thrombolytic drug
  • tested in the IMS II and IMS III trials
EKOS system
Epar

Endovascular Photo Acoustic Recanalization (EPAR)

  • laser-tipped endovascular catheter
  • approx. 1000 pulses/s;  laser energy is converted into acoustic energy
  • recanalization in ~40% of patients according to small studies [Berlis, 2004]
Endovascular Photo Acoustic Recanalization - EPAR
Merci
  • a guidewire along with the Merci catheter is deployed through the catheter and placed beyond the clot (distal thrombectomy)
  • a corkscrew-shaped platinum wire is deployed to grab and ensnare the clot
  • after capturing the clot, the clinician inflates the balloon guide catheter to temporarily stop the forward flow of blood while the clot is withdrawn and pulled into the catheter and out of the body
  • effectiveness in achieving recanalization was demonstrated in the MERCI and MultiMERCI trials
  • currently, stent retrievers are preferred
Merci cathether
Stenting
  • data regarding stenting in acute stroke are limited
  • several small studies showed a high recanalization potential of stenting (79%-95%), but there are no randomized trials to demonstrate a clinical benefit
  • according to AHA/ASA, the procedure is considered experimental, and retrievers are preferred
  • the advantage compared to other methods is the speed and rate of recanalization
  • disadvantages:
    • compression of the thrombus against the vessel wall → risk of perforator occlusion
    • high restenoses rate (up to 32%)
    • need for subsequent DAPT to prevent thrombosis → increased risk of bleeding
  • stenting seems beneficial in acute ICA occlusions with distal embolization (distal embolectomy+CAS)

Advantages and disadvantages of MT

  • wider therapeutic window
  • high recanalization potential
  • can be used in patients with a major IVT contraindication (e.g. after recent surgery, during anticoagulation therapy) or where IVT has failed
  • effective in tPA-resistant occlusions
  • can be used in combination with other revascularization procedures (IVT + IAT + mechanical recanalization)
  • results highly depend on the neurointerventionalist´s experience
  • high costs and requirements for instrumentation and personnel
  • later initiation of therapy compared to IVT
  • complications associated with endovascular procedures (dissection, perforation…)
  • risk of thrombus fragmentation leading to multiple distal embolizations

Indications

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Contraindications

Contraindications are derived from individual trials with thrombectomy, which differ slightly from each other.

Imaging findings

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Personal history, laboratory and clinical findings

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Anticoagulant therapy

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Thrombectomy procedure

Periprocedural monitoring

  • the procedure is performed by a neurointerventionalist and supervised by an anesthesiologist and/or neurologist
  • MT is perfomed in general anesthesia (GA) or conscious sedation (CS)/analgosedation
    • decide individually, CS is preferred
    • the GOLIATH, ANSTROKE and SIESTA  trials did not indicate a worse outcome with GA compared with CS  Comparison of general anesthesia and conscious sedation
    • data from an Italian registry show worse outcomes for patients treated in GA [Cappellari, 2020]
    • disadvantages of GA:
      • neurostatus monitoring is difficult
      • delay in initiation of therapy 
      • higher risk of periprocedural hypotension
  • monitor BP every 5 minutes,  continuous monitoring of pulse and O2 saturation
    • maintain BP < 180/105 mmHg during and after the procedure (24h) (AHA/ASA 2019 IIa/B-NR)
    • according to the analysis of MR CLEAN data, optimal BPs appear to be ~ 135 mmHg, mean BP during MT was 150 mmHg → see here
    • RIGHT-2 and MR ASAP trials are currently ongoing
  • repeated bolus of midazolam (2.5mg) + sufentanil (25ug) is recommended for sedation
  • regularly check neurological status (level of consciousness, speech, visual field, motor skills)

Periprocedural anticoagulation

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Thrombus extraction

  • initial injection with assessment of the site and extent of occlusion, and collateral circulation
  • after passing the catheter through the thrombus, assess the patency of the distal sections, then thrombectomy is initiated
  • perform follow-up injections after stent passage and at the end of the procedure
  • if a tight stenosis or occlusion of the ICA is present, acute angioplasty with/without carotid stenting can be performed [Cohen,2015]   (AHA/ASA 2019 IIb/B-R)
    • fresh occlusion can be usually easily passed through with the guiding wire
    • thrombus extraction followed by carotid angioplasty seems to give better results → see here
    • subsequent antiplatelet therapy (contraindicated after IVT) is problematic if stent is inserted
    • in addition, moving wires through the stented segment may lead to local complications
  • the goal of the procedure is to achieve a TICI of 2b-3
  • the procedure can be combined with the administration of intraarterial thrombolysis (IAT) (AHA/ASA 2019 IIb/C-LD)
    • inaccessible segment, distal embolization [Kaesmacher, 2019]
    • no standardized dosing procedure is available
    • good clinical effect of MT with TICI 2a-3 followed by IAT was reported in the CHOICE trial – the effect can be explained by dissolution of microthrombi in the peripheral circulation
  • if recanalization is achieved,  wait approx. 15 minutes and perform control examination to rule out early reocclusion
  • with residual occlusion(s) in distal segments, consider the benefit and risk of complications of continued procedure
  • if recanalization is not achieved, the procedure is ended:
    • after repeated unsuccessful extractions (approximately 6 attempts)
    • when sICH is suspected
  • after successful extraction, seek Early Venous Filling (EVF) at follow-up injection Early venous filling (EVF)
    • EVF is defined as filling of any vein earlier than the late arterial phase (Elands, 2021)
    • EVF is a marker of hyperperfusion and increased risk of hemorrhagic transformation
    • EVF is assessed simply as present or absent
ICA recanalization with the ERICretriever

M1 occlusion treated with Solitaire retriever

Quality indicators of the neurointervention program
  • number of recanalizations TICI 2b-3
  • door to groin time
  • CT to groin time
  • groin to recanalisation time
  • complications rate

Postprocedural care

  • the sheath is extracted in the angio suite and entry is secured with an occluder (Perclose, Mynxgrip, AngioSeal ) Angioseal
    • an alternative to occluder is groin compression (manual, using Femostop, etc.)  Femostop
  • the patient is transported to the ICU;  if SAH or ICH is suspected, perform a repeated CT scan
  • in the ICU, continue with the monitoring of vital signs (BP measurement in the first hour every 15 min, then every 30 min for at least 24h)
  • maintain BP < 180/105 mmHg (AHA/ASA 2018 IIb/B-NR)
    • aggressive BP treatment (< 130/80 mmHg) may be beneficial   Blood pressure after mechanical thrombectomy and mRS    Blood pressure after mechanical thrombectomy    [Choi, 2019]
  • monitor neurological status (NIHSS, GCS), search for possible complications
  • it bridging therapy with tPA was used:
    • monitor for bleeding (puncture, gingival, GIT, urogenital bleeding, etc.) → see IVT protocol
    • NG tube and central venous catheter must not be inserted; arterial puncture must not be performed in the first 24 h after IVT
    • IM. injections must not be administered for approx. 1 h after the tPA administration
    • CBC + coagulation (aPTT, TT, F, Q, INR) at 6 and 12 h, CBC+coagulation+biochemistry the following day
  • perform follow-up brain CT scan in 22-36 h

Postprocedural antithrombotic medication

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Grading of cerebral revascularization

Complications

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