Failed Thrombectomy - SLICE Worldwide 2021

Management of difficult thrombectomy resulting in unproductive passes due to:

• ICAD
• refractory clots:
  1. white thrombi (with pinching technique)
  2. bifurcation thrombi (with double stent-retriever technique)
  3. calcified emboli (with initial/rescue stenting)

Highlights*: the newest devices on the market: Clotild and Thromb X

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Failed thrombectomy reasons:

1. ICAD:
   • typically mid-basilar location
   • multifocal disease (located also in others intracranial vessels)
   • geographically dependent (higher prevalence in Asian population)
   • can manifest as fluctuating stroke à fluctuations of the blood flow and hypoperfusion

MID-BA ICAD MANAGEMENT step-by-step:

It is important to prove the ICAD à run from ipsilateral ICA to reveal the presence of PCoM and patency of the top of BA and PCAs

- sheath at the origin of VA

- run from the VA

- gentle aspiration at the level of the ICAD from aspiration catheter to clean up the lesion because there will be always some clot on the ruptured atherosclerotic plaque

- once the lesion is cleaned and ICAD confirmed, the stenosis can be passed by microcatheter and SR can be introduced and opened at the level of stenosis 

1. in the case: Tigertriever (opening and radial force of the device can be adjusted by operator) – allows angioplasty with stent, possibility of by-pass injection and gentle removal of the device when it is closed with less risk of plaque injury

- Dyna-CT to exclude the hemorrhage

- if there is no bleeding – introduction of antiplatelet therapy (Integrilin iv.) 

- coronary balloon angioplasty of the lesion

1. in the case: AICAs occlusion post PTA àchange the device for Sophia 5 and aspiration + watch and wait à restoration of both AICAs and preserved patency of BA 

Special remarks:

*pay attention to washout from the competitive flow – do not confuse it with occlusion

- characteristic run pattern: up and down

*do the run after 1st pass very quickly otherwise the lesion may reocclude and you will not see the point of the stenosis

*do not finish the procedure immediately after successful recanalization, do delayed runs of stenosis because it can occlude with a delay

 First-line contact aspiration vs. stent-retriever in ICAD according to publication and Slice Faculty: 

• publication (Dong-Hun Kang): better results with stent-retriever than aspiration
• general opinion of the Faculty: SR > aspiration in ICAD
  • cleaning may be better with SR than with aspiration due to better apposition of the device to the thrombus, but there is a risk of aggravation of thrombotic activity in ruptured plaque with SR pass – Slice Faculty
  • in fact aspiration may be more aggressive for vessel wall than SR (risk of dissection)

Antiplatelet therapy in ICAD:

• it is very important to treat patient simultaneously with antiplatelet therapy (Tirofiban, Cangrelor, Integrilin iv.) 
• if the degree of suspicion of ICAD is mild to moderate – the antiplatelet therapy may be introduced after the first pass, if it is high – before the procedure
• Tirofiban is better than Cangrelor when there is already clot in stenosis
• Tirofiban iv in also mostly used in publication data 
• example of protocol for Tirofiban (Montpellier): bolus dose of 4 µg/kg, maintenance dose of 0,1 µg/kg /min for 12 hours
• if you need to implant stent at the level of stenosis, be aware to start the infusion 20 minutes before the placement
• Cangrelor is advantageous because of its very short time of action and reversibility compare to other drugs
• after the procedure: Ticagrelor 90 mg and overlap of the infusion of Integrilin during 6 hours (bridging therapy), then cessation of Interilin

Highlight*:

•  Sensome – Clotild – a wire combined with a sensor which allows to interrogate the environment that the wire find itself in = vessel lumen assessment: 
•  identification of thrombus type and location 
• detection of stenosis or dissection

2 . REFRACTORY CLOTS:

 A) WHITE THROMBI:

• frequent cause of unproductive passes 
• device designed for white clots: Nimbus (Cerenovus)
• technique recommended for white clots: pinching technique

PINCHING TECHNIQUE step by step

- pass with wire and microcatheter between the thrombus and the vessel wall

- introduce the Nimbus device, position it properly (tip to tip with microcatheter, the dense marker few millimeters behind the front of the thrombus) and unsheathe it 

- push the microcatheter while slightly pulling back the Nimbus until you feel resistance = pinning the clot (you can use torque device to better control the wire of the stent and block it after pinning to keep the tension on the stent)

- retrieve en bloc: intermediate catheter-microcatheter-SR while maintaining the tension on microcatheter, aspirate from the BCG and/or aspiration catheter

*if the clot is trapped in BCG – keep negative pressure on the balloon, deflate it and remove it (long sheath can be beneficial in these cases)

Highlight*:

• Thromb X device – a SR that allows to grab the thrombus between its proximal and distal part and then trap it in three dimensions by closing up the two parts of the stent:
  1. allows 3D pinching

 B) BIFURCATION THROMBI:

• technique recommended for bifurcation clots: double stent-retriever technique (second line treatment)

Double stent-retriever technique - applications:

- T occlusion

- flip flopping bifurcation MCA clot 

- sticky rolling thrombus

- second line treatment in other types of clots

DOUBLE STENT-RETRIEVER TECHNIQUE step by step:

- deploy the first SR (MCA) via microcatheter and remove the microcatheter 

- place the same microcatheter in second occluded branch (ACA) and deploy the second SR 

                              or

- go through BCG: deploy the first SR and partially recapture it with microcatheter so you could easily pass to the second branch with another device

- place the second SR in the second occluded branch

- remove both microcatheters

- do a blind exchange using an aspiration catheter*

*double stent technique may generate lot of frictions – to improve the safety you can use an intracranial catheter and/or reduce the length of opened stents

- possible combination of stents:

1. 2 x 4 mm
2. 1 x 4 mm via 0,021 in and 1 x 3 mm via 0,017 in
3. 1 x 6 mm and 1 x 4 mm 
4. CALICIFIED EMBOLI

• prevalence ~ 1,3-1,8%
• lower results of TICI, lower mRS and higher mortality compare to the other MTs
• can manifest as partial occlusion and watershed infarction 
• technique recommended for calcified emboli: initial/rescue stenting

INITIAL/RESCUE STENTING step by step

- if you are sure that it is calcified emboli, you can go directly with stenting

- if you are not sure, try first attempt as usually in MT with either aspiration or SR (sometimes calcification is combined with thrombus)

- it can be difficult to even cross the lesion with a microcatheter and a wire

- 20 min before stent-implantation, give GP IIb/IIIa inhibitor to the patient (you should never combine it with heparin because of high risk of hemorrhage)

- depending on the size of calcification, the concomitant thrombus and their location, you can use self-expanding stents or balloon-mounted stents

- stent types in use (mandatory: high radial force and/or oversizing): Wingspan, Enterprise, Atlas, Credo, Solitaire AB, balloon-mounted stents (with caution because of higher risk of rupture) 

Rescue stenting for failed mechanical thrombectomy (in publication):

• higher rate of good outcome mRS 0-2 without increasing symptomatic intracranial hemorrhage compare to no rescue stenting
• GP IIb/IIIa inhibitor significantly associated with stent patency