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Advanced Neurology Rescue stenting in mechanical thrombectomy

9.7 million in 2050, with disability-adjusted life years lost an endovascular attempt to restore arterial patency. Scores
rising from 144.8 million in 2020 to 189.3 million in 2050. range from 0 (no perfusion) to 3 (full perfusion with filling
1
These projections emphasize the importance of efficacious of all distal branches). mTICI included grade 2C: near-
33
therapeutic strategies. Mechanical thrombectomy (MT) complete perfusion with delayed flow or distal emboli in a
has revolutionized large vessel occlusions (LVOs) stroke few distal cortical vessels. 34-38 The expanded TICI (eTICI)
care, significantly improving the prospects of both score includes grade 2b50 representing reperfusion of 50 –
technical success and favorable functional outcomes. 2-15 66% of the territory and grade 2b67 indicating reperfusion
Effectiveness of clot retrieval can be broadly categorized of 67 – 89% at the completion of the procedure. 39
into vascular access and clot retrieval. 16-18 Several studies Successful recanalization is defined as the filling of 50%
reported difficulty reaching the thrombus in 10 – 20% or more of the distal territory. This can be described as
33
whereas the remainder was attributed to the inability a mTICI score of at least 2b or eTICI 2b67. 34,39 Refractory
to retrieve the clot once adequate intracranial access MT is defined as unsuccessful reperfusion (TICI 0 – 1
was established. 19-22 Successful recanalization (modified reperfusion) or vessel reocclusion identified within 72 h of
thrombolysis in cerebral infarction [mTICI] ≥2b) successful thrombectomy. 29,40
independently predicts favorable functional outcomes,
particularly with achieving complete or near-complete Refractory MT is defined as an eTICI or mTICI score
reperfusion. 19,23 Rescue stenting (RS) has emerged as a safe <2b50 at the completion of the procedure. This definition
and effective strategy in occlusions refractory to MT. 24-28 of MT failure is independent of the first-line technique and
Several factors have been suggested in refractory MT, whether multiple techniques were used. Typically, three
including intracranial atherosclerotic stenosis (ICAS), or more passes are attempted before declaring treatment
39
intracranial dissections (IADs), or recalcitrant emboli. 29-31 failure. Cases where it is not possible to technically reach
The implementation of RS involves a thorough evaluation the point of closure are excluded. We propose that severe
of patient-specific factors, lesion traits, and anatomical residual stenosis is defined as stenosis of 70% or more of
considerations to ensure good outcomes. 32 the target vessel following successful recanalization.
In this review, we examine the current understanding Rescue treatment encompasses endovascular strategies
of the use of RS for intracranial stenosis-related LVO that may be offered for unsuccessful recanalization or
(ICAS-LVO) or refractory MT, including epidemiology, instant reocclusion in acute ischemic stroke from LVO
pathophysiology, current evidence supporting RS in the to maximize recanalization rates using alternative access
anterior and posterior circulation, stents used, endovascular routes, local intra-arterial (IA) thrombolysis, balloon
techniques, patient population, antithrombotic use, risks, angioplasty with or without stenting, and RS. 24-28,41,42
and complications.
2.2. Epidemiology
2. Methods Successful recanalization rates of MT for anterior and
To conduct this narrative review, we searched PubMed posterior circulation LVOs are comparable and estimated
and MEDLINE databases for the following keywords: to be over 80%. 7,43-47 The success of MT depends on several
“endovascular or thrombectomy” and “rescue” or “rescue factors, including the patient’s age, comorbidities, stroke
stenting” or “stenting” from 2012 to 2024. We also searched etiology, clot composition, the time from symptom onset
the following keywords, “intracranial atherosclerotic to treatment, the location and size of the occlusion, clot
disease” and “endovascular” or “thrombectomy.” All imaging characteristics (hyperdense artery sign), and
references yielded were reviewed and grouped into categories technique used. 48-50
such as epidemiology, pathophysiology, current evidence, Based on the observational studies examining the
endovascular techniques and stents, antithrombotic use, etiologies of refractory thrombectomy in North America,
and complications. ICAS was found to be the most common etiology,
accounting for 60 – 75% of cases. 20,29 Less common
2.1. Definitions causes were complex anatomy, IA dissection, chronic
There are several definitions to review with regard to occlusion, distal emboli, or rarely vasospasm or device
angiographic reperfusion, residual stenosis, and rescue malfunction. 20,29
treatment. Variations in these definitions exist, hence we The prevalence of ICAS underlying refractory MT in
summarize commonly utilized terms as below.
Asian populations has a higher burden accounting for
The thrombolysis in cerebral infarction (TICI) scale was most refractory MT cases, and less frequently, intracranial
used to evaluate angiographic intracranial reperfusion after arterial dissection or recalcitrant emboli. 51,52 Several studies

Volume 3 Issue 3 (2024) 2 doi: 10.36922/an.3950