Retrievable stents, “stentrievers,” for endovascular acute ischemic stroke therapy

Abstract

Endovascular therapy for acute ischemic stroke continues to evolve to improve both efficacy and safety. In the late 1990s, intra-arterial chemical thrombolysis with prourokinase was shown to be effective in achieving partial recanalization and improving clinical outcome, in comparison with intra-arterial heparin administration. However, this was at the expense of an increase in the rate of symptomatic intracranial hemorrhage to 10%. To improve the rate of recanalization, expand the time window, and reduce the risk of symptomatic intracranial hemorrhage, mechanical thrombectomy was introduced, with initial approval of the Merci clot retriever, a corkscrew-like device, and then more recently with approval of the Penumbra thromboaspiration system. Both devices are associated with a high rate of recanalization (total, partial, and complete). However, time to recanalization was on average 45 minutes, with a low rate of complete clot resolution, given that the majority of patients achieved only partial recanalization. More recently, retrievable stents have shown promise in reducing the time to recanalization, and they achieve a higher rate of complete clot resolution with improved feasibility. The retrievable stent can be opened within the clot to engage it within the stent struts, and subsequently it is retrieved by pulling it under flow arrest. The retrievable stents provide a new tool in the armamentarium of devices that can be used to achieve safe and timely clot removal. This review provides the historical evolution of endovascular therapy to use of stentreivers. Neurology ® 2012;79 (Suppl 1):S148-S157 GLOSSARY AIS ϭ acute ischemic stroke; CI ϭ confidence interval; ECASS ϭ European Cooperative Acute Stroke Study; FDA ϭ US Food and Drug Administration; IA ϭ intra-arterial; ICA ϭ internal carotid artery; ICH ϭ intracerebral hemorrhage; IMS ϭ Interventional Management of Stroke; MCA ϭ middle cerebral artery; mRS ϭ modified Rankin Scale; NIHSS ϭ NIH Stroke Scale; NINDS ϭ National Institute of Neurological Disorders and Stroke; OR ϭ odds ratio; PROACT ϭ Prolyse in Acute Cerebral Thromboembolism; RSs ϭ retrievable stents; rtPA ϭ recombinant tissue plasminogen activator; SESs ϭ self-expanding stents; SWIFT ‫؍‬ Solitaire FR With the Intention for Thrombectomy; TICI ϭ thrombolysis in cerebral ischemia; TIMI ϭ thrombolysis in myocardial infarction.Acute ischemic stroke (AIS) therapy is based on the concept that early recanalization of the occluded artery leads to improved clinical outcome through preservation of the time-sensitive penumbra.1-3 There has been an evolution in the development of techniques used to achieve faster and safer rates of recanalization. Because of the limited efficacy of pharmacologic thrombolysis, mechanical and multimodality methods have been sought to aid revascularization of the occluded artery. A newer endovascular approach using retrievable stents (RSs) shows promising results for better and faster rates of recanalization with possibly better shortterm outcomes.

Medical and Endovascular Treatment of Patients with Large Vessel Occlusion Presenting with Mild Symptoms: An Observational Multicenter Study

“…The efficacy of ET in recanalizing occluded arteries is well established, particularly using stentrievers [17]. However, previous studies also suggest that ET may be particularly beneficial in patients with severe symptoms [18].…”

Recanalization and Mortality Rates of Thrombectomy With Stent-Retrievers in Octogenarian Patients with Acute Ischemic Stroke

“…This tendency might be partly explained by the results of previous studies, which show that the mortality rate after different treatments (intravenous thrombolysis, intra-arterial thrombolysis, mechanical thrombectomy with classic retrievers) is higher in octogenarians than in younger patients, conveying increased age a higher rate of stroke-related death [2][3][4]. In the past years, stent-retrievers seem to have opened a new window in the field of mechanical thrombectomy, achieving better angiographic and clinical outcomes than classic retrievers [5,6], but their effect and security in the older patients have scarcely been reported [7]. We present the results of a series of octogenarians patients who were treated with stent-retrievers, compare them with a control group, and discuss the topic of endovascular treatment of acute stroke in octogenarians.…”

Immunohistochemical Analysis of Thrombi Retrieved During Treatment of Acute Ischemic Stroke

“…2 Most recently, a new class of mechanical thrombectomy devices has emerged with reported recanalization rates ranging from 67% to 100%. 3,4 However, the stress to the vessel wall related to stent-retrieval seems important. During retraction of the stent-retriever, the vascular anatomy may be distorted and considerable vasospasm of the target vessel and along the course of the stent-retriever are observed on a regular basis.…”