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EDITORIAL COMMENTARY
Year : 2022 | Volume
: 25
| Issue : 6 | Page : 993-994
Commentary on - Rescue strategies in anterior circulation stroke with failed mechanical thrombectomy (RAFT)
Gigy Kuruttukulam, Kaushik Sundar
Stroke Neurologist and Head, Rajagiri Hospital, Aluva, Kerala, Consultant and Clinical Lead for Comprehensive Stroke Care, NH Group of Hospitals, Kolkata, West Bengal, India
Correspondence Address:
Gigy Kuruttukulam
Stroke Neurologist and Head, Rajagiri Hospital, Chunangamvely Aluva, Kochi - 683 112, Kerala
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/aian.aian_1092_21
How to cite this article:Mechanical thrombectomy (MT) is a “game changer,” when it comes to treating large vessel occlusions, especially in the anterior circulation. However, a meta-analysis of the five most important randomized controlled trials of MT revealed that the recanalization failure rates following MT were as high as 29%.[1] Newer studies have shown that large vessel recanalization—first pass or otherwise—is one of the most important factors that contribute to the outcome of acute stroke. This brings forward the following question: If a patient presents with a large vessel occlusion (in the window period) and MT has failed to recanalize the vessel, should we offer a rescue strategy to improve his/her recanalization chances, which in turn would translate as better stroke outcomes? Sadly, very few studies have addressed this issue. Rescue strategies in anterior circulation stroke with failed mechanical thrombectomy (RAFT) have tried answering this in their study and the results look promising.[2]
Intracranial atherosclerotic disease (ICAD) is a very important factor that contributes to failed recanalization after MT. Studies suggest that ICADs may contribute to approximately 30–50% of ischemic strokes in the Asian population. Stenting and Aggressive Medical Management for the Prevention of Recurrent Stroke in Intracranial Stenosis (SAMPPRIS) trial[3] was one of the first trials that looked at intracranial stenting for patients with high-grade intracranial stenosis. This was followed by the Vitesse Intracranial Stent Study for Ischemic Therapy (VISSIT) trial.[4] Both of them concluded that medical management was better than interventional procedures for intracranial stenosis. But both these studies had limitations - a 600 mg clopidogrel loading dose, limited operator experience, high dose of heparin, relaxed periprocedural monitoring, and inadequate blood pressure (BP) management could have all contributed to worse outcomes. Interestingly, if we were to consider prevention of disabling or fatal strokes as a primary endpoint in the SAMPPRIS trial, then the medically treated patients were more likely to have disabling/fatal strokes compared to the interventional arm at 30 days follow-up and this was statistically significant. In simple words, if we reduce the periprocedural complications following intracranial stenting, stenting might significantly reduce the risk of fatal or disabling strokes at long-term follow-up. SAMPPRIS and VISSIT trials are analogous to the earlier MT trials, wherein older devices and poor selection criteria led to bad clinical outcomes. Recent studies have shown that careful patient selection, stenting ≥7 days after a stroke/TIA, experienced operators, and optimal periprocedural management are associated with a much lower risk of periprocedural complications of intracranial stenting by 2%–4.3%.[5]
The first interventional treatment for medically refractory intracranial stenosis was done as early as 1980,[6] wherein two patients with basilar artery stenosis were treated with balloon angioplasty. Subsequently, angioplasty was tried as a treatment for intracranial stenosis. However, angioplasty was associated with risks of intimal dissection, thrombosis, and vessel rupture. Noting these results, subsequent studies looked at slow inflation and under-sizing of the balloon.[7] This resulted in lesser periprocedural complications but did not achieve the desired angiographic effect of an open vessel. Such low-profile balloons are comparable to recent stent retriever thrombectomy devices, whose deployment is nearly equivalent to an angioplasty. Intracranial angioplasty opens the vessel up, but the effect is usually temporary. Thus, in the setting of intracranial stenosis, angioplasty alone is probably not going to result in successful clinical outcomes.
Though stenting for ICAD with recurrent strokes or TIAs is being extensively studied, rescue stenting in the setting of large vessel occlusions has not been well established. As much as it looks like a lucrative option, there are some glaring gaps. The first problem that we face is the antithrombotic regimen. Many patients undergoing MT would have received thrombolytics. Therefore, initiation of antithrombotics in them could be tricky. More importantly, it is difficult to predict reperfusion injury in these patients or anticipate the need for a decompressive craniectomy. Antiplatelets in these settings could be catastrophic. Secondly, the choice of stents we have for rescue procedures is limited. Many studies have previously used balloon-mounted coronary for rescue stenting. But its trackability across tortuous anatomy and deployment across complex lesions is a challenge. Intracranial stents that have been used for rescue stenting are self-expandable stents that are deployed by unsheathing a microcatheter. These stents were originally designed for other purposes - such as the treatment of complex wide neck aneurysms or dissections. They have excellent trackability but lack radial strength. Hence, structural support to keep the vessel open might be theoretically lacking. But cerebral arteries, unlike systemic arteries, have a paucity of elastic fibers in the medial layer and a very thin adventitia. This implies that the radial force needed to keep these vessels open is possibly low. There are stent retrievers currently available in the market that can do the job of MT and can also if need be, detached across the stenotic lesion. This would make the job of an interventionist easy during emergency procedures. The third important problem we face is the cost. MT per se is an expensive procedure. Adding the cost of an intracranial stent to this would make things difficult, especially if the healthcare costs are directly passed on to the patient's relatives.
Recent studies including the RAFT study from India and similar studies abroad have demonstrated that rescue stenting is a safe and effective procedure for failed MTs.[2] One study showed that rescue stenting resulted in successful recanalization in close to 65% of patients with failed recanalization after MT. With careful post-interventional monitoring and adequate BP control, the incidence of symptomatic intracranial hemorrhage between the rescue stenting and control groups was similar. If periprocedural complications are reduced and the cost of intracranial stenting is manageable, then rescue stenting in an acute setting will emerge from a clinical equipoise to a promising treatment strategy.
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