Self-expanding stent for recanalization of acute embolic or dissecting intracranial artery occlusion

Refractory Stroke Thrombectomy: Prevalence, Etiology, and Adjunctive Treatment in a North American Cohort

BACKGROUND AND PURPOSE

Acute stroke intervention refractory to mechanical thrombectomy may be due to underlying vessel wall pathology including intracranial atherosclerotic disease and intracranial arterial dissection or recalcitrant emboli. We studied the prevalence and etiology of refractory thrombectomy, the safety and efficacy of adjunctive interventions in a North American-based cohort.

MATERIALS AND METHODS

We performed a multicenter, retrospective study of refractory thrombectomy, defined as unsuccessful recanalization, vessel reocclusion in <72 hours, or required adjunctive antiplatelet glycoprotein IIb/IIIa inhibitors, intracranial angioplasty and/or stenting to achieve and maintain reperfusion. Clinical and imaging criteria differentiated etiologies for refractory thrombectomy. Baseline demographics, cerebrovascular risk factors, technical/clinical outcomes, and procedural safety/complications were compared between refractory and standard thrombectomy groups. Multivariable logistic regression analysis was performed to determine independent predictors of refractory thrombectomy.

RESULTS

Refractory thrombectomy was identified in 25/302 cases (8.3%), correlated with diabetes (44% versus 22%, P = .02) as an independent predictor with OR = 2.72 (95% CI, 1.05-7.09; P = .04) and inversely correlated with atrial fibrillation (16% versus 45.7%, P = .005). Refractory etiologies were secondary to recalcitrant emboli (20%), intracranial atherosclerotic disease (60%), and/or intracranial arterial dissection (44%). Four (16%) patients were diagnosed with early vessel reocclusion, and 21 patients underwent adjunctive salvage interventions with glycoprotein IIb/IIIa inhibitor infusion alone (32%) or intracranial angioplasty and/or stenting (52%). There were no significant differences in TICI 2b/3 reperfusion efficacy (85.7% versus 90.9%, P = .48), symptomatic intracranial hemorrhage rates (0% versus 9%, P = .24), favorable clinical outcomes (39.1% versus 48.3%, P = .51), or mortality (13% versus 28.3%, P = .14) versus standard thrombectomy.

CONCLUSIONS

Refractory stroke thrombectomy is encountered in <10% of cases, independently associated with diabetes, and related to underlying vessel wall pathology (intracranial atherosclerotic disease and/or intracranial arterial dissection) or, less commonly, recalcitrant emboli. Emergent salvage interventions with glycoprotein IIb/IIIa inhibitors or intracranial angioplasty and/or stenting are safe and effective adjunctive treatments.

Acute ischemic stroke endovascular therapy

Endovascular therapy (EVT) has become the standard treatment for large-vessel occlusion (LVO) acute ischemic stroke (AIS). EVT is now indicated in patients up to 24h from their last known well, provided that the patient meets specific clinical and imaging criteria. Improvements in thrombectomy devices, techniques, and operator experience have allowed successful EVT of ICA terminus, M1-MCA occlusions as well as proximal M2-MCA, basilar artery occlusions, and revascularization of tandem lesions. Mechanical thrombectomy failures still occur due to several factors, however, highlighting the need for further device and technical improvements. An ongoing debate exists regarding the need for pre-EVT thrombolytic agents, thrombectomy techniques, distal occlusions, anesthesia methods, the role of advanced neuroimaging, the treatment of patients with larger infarct core, and those presenting with milder stroke symptoms. Many of these questions are the subject of current or upcoming clinical trials. This review aims to provide an outline and discussion about the established recommendations and emerging topics regarding EVT for LVO AIS.

Causes and Solutions of Endovascular Treatment Failure

In a meta-analysis of individual patient data from 5 randomized controlled trials, endovascular treatment (EVT) mainly using a stent retriever achieved successful recanalization in 71.1% of patients suffering from acute stroke due to anterior circulation large artery occlusion (LAO). However, EVT still failed in 28.9% of LAO cases in those 5 successful trials. Stent retriever failure may occur due to anatomical challenges (e.g., a tortuous arterial tree from the aortic arch to a target occlusion site), a large quantity of clots, tandem occlusion, clot characteristics (fresh versus organized clots), different pathomechanisms (embolic versus non-embolic occlusion), etc. Given that recanalization success is the most important factor in the neurological outcome of acute stroke patients, it is important to seek solutions for such difficult cases. In this review, the basic technique of EVT is briefly summarized and then various difficult cases with diverse conditions are discussed along with suggested solutions.

A Novel Canine Model of Acute Vertebral Artery Occlusion

Background

The extended time window and theoretic reduction in hemorrhage make mechanical strategies an attractive approach for the treatment of patients with ischemic stroke. However, a limited availability of suitable animal models of cerebrovascular thrombosis has hampered the study of novel endovascular interventions. The aim of the present study was to develop a new technique for site-specific placement of a thrombus in a canine model that would allow for the evaluation of mechanical thrombectomy and clot retrieval methods and the visualization of thrombus dislocation or fragmentation during angiographic manipulation.

Methods

Angiography and embolization with a preformed thrombus were performed in 12 canines. Under fluoroscopic guidance, an embolism protection device (EPD) was anchored to the middle segment of the left vertebral artery (VA) via the left femoral arterial sheath. A preformed radiopaque clot was injected through the guide catheter into the left VA, via the contralateral femoral artery, proximal to the EPD. After 15 min of occlusion, the EPD was removed and persistent occlusion of the VA was documented angiographically.

Results

Angiography performed during the observation period confirmed the persistence of VA occlusion in each case, and displacement of the radiopaque clots did not occur during the 3-hour observation period. The technique allowed selective embolization of targeted vessels without thrombus fragmentation.

Conclusion

This study demonstrates, for the first time, a canine model of post-circulation embolism induced by autologous blood clot placement. This model can be rapidly formed and easily operated, and the site of thrombosis can be readily controlled.

Recanalization of acute intracranial artery occlusion using temporary endovascular bypass technique

PURPOSE

The purpose of this study is to present our preliminary experience of the temporary endovascular bypass (TEB) technique using an Enterprise stent for recanalization of acute intracranial artery (IA) occlusion.

MATERIALS AND METHODS

Patients treated by TEB were enrolled in this retrospective study from January 2009 to May 2010. All the procedures consist of temporary partial deployment and subsequent retrieval of Enterprise stent, supplemented by intra-arterial infusion of urokinase (UK) and/or tirofiban. According to the thrombolysis in cerebral infarction (TICI) classification, recanalization was evaluated with initial and postprocedural angiography. Safety was evaluated related to the procedure and clinical outcomes were assessed by National Institute of Health Stroke Scale (NIHSS) score at discharge and modified Rankin scale (mRS) score at 3 months.

RESULTS

Eleven patients (median NIHSS 12.8, mean age 61.6 years, male: female = 8:3) with acute IA occlusion were treated with TEB. All the patients presented with TICI 0, and the occluded vessel was the middle cerebral artery (n=7), the basilar artery (n=1), and the distal ICA occlusion (n = 3). IV infusion of tissue plasminogen activator (tPA) was done in 4 patients and mechanical thrombolysis with intra-arterial UK was performed in 9. Recanalization was achieved in 73% (8 patients; TICI ≥ 2). There were no procedure-related complications except for two asymptomatic intracranial hemorrhages. Improvement (≥ 4 points on the NIHSS) and good outcome (mRS ≤2) after 90 days was shown in six patients (55%). One patient died 6 days after procedure.

CONCLUSION

TEB may be a valuable treatment option in acute thromboembolic IA occlusion without stent implantation.

Safety and efficacy of mechanical thrombectomy with solitaire stent retrieval for acute ischemic stroke: a systematic review

Purpose

In recent years, mechanical thrombectomy using Solitaire stent retrieval has been tried for treating acute ischemic stroke with a large artery occlusion. We systematically reviewed published articles to appraise the evidence that supports the safety and efficacy of the mechanical thrombectomy in acute strokes with Solitaire stent.

Materials and Methods

Systematic searches using Medline and Scopus were performed for studies evaluating mechanical thrombectomy using a Solitaire stent in acute ischemic stroke. Articles were included if they were published since 2008, contained at least 5 subjects, and provided clinical results.

Results

Thirteen articles (262 cases) were included in this review. The mean time of the procedures ranged from 37 to 95.6 minutes in 10 studies. The success of recanalization was achieved in 89.7% and the recanalization rate varied from 66.7% to 100% in all 13 studies. The overall rates of the symptomatic hemorrhagic complications and mortality were 6.8% and 11.1%, respectively. A favorable outcome of mRS 2 or under was 47.3%. Procedure-induced complications developed in 3.4%.

Conclusion

The present review suggested that mechanical thrombectomy using a Solitaire stent in acute ischemic stroke was effective in recanalizing the occluded artery. The rate of procedural complications was small.

Stenting in the treatment of acute ischemic stroke: literature review

Recanalization of acute large artery occlusions is a strong predictor of good outcome. The development of thrombectomy devices resulted in a significant improvement in recanalization rates compared to thrombolytics alone. However, clinical trials and registries with these thrombectomy devices in acute ischemic stroke (AIS) have shown recanalization rates in the range of 40-81%. The last decade has seen the development of nickel titanium self-expandable stents (SES). These stents, in contrast to balloon-mounted stents, allow better navigability and deployment in tortuous vessels and therefore are optimal for the cerebral circulation. SES were initially used for stent-assisted coil embolization of intracranial aneurysms and for treatment of intracranial stenosis. However, a few authors have recently reported feasibility of deployment of SES in AIS. The use of these devices yielded higher recanalization rates compared to traditional thrombectomy devices. Encouraged by these results, retrievable SES systems have been recently used in AIS. These devices offer the advantage of resheathing and retrieving of the stent even after full deployment. Some of these stents can also be detached in case permanent stent placement is needed. Retrievable SES are being used in Europe and currently tested in clinical trials in the United States. We review the recent literature in the use of stents for the treatment of AIS secondary to large vessel occlusion.

Comparison of the Incidence of parenchymal hematoma and poor outcome in patients with carotid terminus occlusion treated with intra-arterial urokinase alone or with combined IV rtPA and intra-arterial urokinase

BACKGROUND AND PURPOSE

Patients with acute CTO generally have a poor prognosis, despite IV or IA thrombolytic treatment. The goal of this study was to analyze the results of patients with CTO who had IA urokinase treatment with or without initial IV rtPA based on a bridging protocol.

MATERIALS AND METHODS

Sixteen consecutive patients with acute ischemic stroke due to CTO who had combined IV and IA or a single IA thrombolytic treatment were enrolled. The baseline characteristics and prognosis were described. The patients who did and did not develop a PH shortly after treatment were compared.

RESULTS

The mean age was 66.4 years, and the median initial NIHSS score was 17. The median dose of IA urokinase was 320,000 U, and recanalization (TICI grade II-III) was achieved in 12 patients (75%). However, 5 patients died and 10 patients had poor prognosis with mRS 5-6 at discharge. Six patients (37.5%) with a PH had a higher NIHSS score 1 day after treatment (26.7 versus 13.6, P = .002), and they had more frequent mortality (66.7% versus 10.0%, P = .018) and worse prognosis (mRS 5-6; 100% versus 40%, P = .016) at discharge than patients without PH.

CONCLUSIONS

Patients with CTO who received IA urokinase treatment based on a bridging protocol had a poor prognosis. The development of PH might affect this outcome.

Mechanical thrombectomy with a self-expanding retrievable intracranial stent (Solitaire AB): experience in 26 patients with acute cerebral artery occlusion

BACKGROUND AND PURPOSE

Patients with stroke unsuitable for IV thrombolysis may be considered for endovascular revascularization, particularly when baseline imaging suggests proximal cerebral vessel occlusion associated with minimal established infarction. This retrospective review describes the use of a self-expanding retrievable intracranial stent (Solitaire AB) for thrombectomy in acute ischemic stroke.

MATERIALS AND METHODS

Twenty-six consecutive patients with stroke treated endovascularly by using the Solitaire stent were identified, followed by detailed review of data extracted from their imaging and clinical records.

RESULTS

Recanalization (TIMI grade ≥2) was achieved with Solitaire thrombectomy as the single treatment technique in 16 patients and in combination with urokinase or the Penumbra device in 9 of the remaining 10 patients. Two patients had symptomatic intracranial hemorrhage. A favorable clinical outcome (mRS score of ≤2) was seen in 3 of 5 patients with MCA occlusion, 6 of 11 (55%) patients with ICA occlusion, and 2 of 10 patients with BA occlusion.

CONCLUSIONS

Mechanical thrombectomy by using the Solitaire stent appears to be safe and is capable of achieving a high rate of recanalization and favorable clinical outcomes in patients presenting with proximal cerebral vessel occlusion.

Stent placement for flow restoration in acute ischemic stroke: a single-center experience with the Solitaire stent system

BACKGROUND AND PURPOSE

In acute thromboembolic stroke, mechanical recanalization with stents may result in immediate flow restoration. The Solitaire stent can be used both for flow restoration and thrombectomy. In this single-center experience, we report safety and efficacy data on the application of the Solitaire stent.

MATERIALS AND METHODS

Between March 2009 and July 2010, 18 patients were treated with the Solitaire stent. To evaluate perfusion of the occluded vessel segment before and after the intervention, the TICI score was used (0-3). Clinical outcome was assessed by using the mRS at discharge.

RESULTS

Overall, recanalization was successful in 16 of 18 patients (88.8%). There were no procedure-related complications. Mean TICI score after the intervention was 2.3 ± 0.8. In 5 patients, reocclusion of the treated vessel occurred immediately after retrieval of the temporarily opened stent, and permanent stent deployment was performed to maintain stable perfusion. In 3 patients, hemorrhage occurred after successful recanalization. Five patients died (infarction, n = 3; hemorrhage, n = 1; organ failure, n = 1). A good clinical outcome (mRS ≤2) was achieved in 33.3% of the patients, 5.5% had a moderate outcome (mRS, 3/4), and 61.2% had a poor outcome or died (mRS, 5/6).

CONCLUSIONS

Application of the Solitaire stent in acute stroke results in a high recanalization rate (88.8%) without procedural complications and with a good outcome in one-third of patients. These results encourage further evaluation of the stent in larger patient populations.

Initial experience with a self-expanding retrievable stent for recanalization of large vessel occlusions in acute ischemic stroke

INTRODUCTION

Quicker recanalization results in better clinical outcomes in patients with acute ischemic strokes. We describe our experience with the use of a self-expanding, fully retrievable stent in acute intracranial occlusions.

METHODS

Patients who underwent intra-arterial procedures with a self-expanding, fully retrievable stent for acute ischemic strokes at our center in 2009 were included in this study. The primary outcome was recanalization [Thrombolysis in Myocardial Infarction (TIMI) grade 2/3] at end of procedure. Secondary endpoints were procedural interval times, incidence of vasospasm, rupture of vessels, device-related complications, groin complications, postprocedural intracerebral hemorrhage (ICH) on noncontrast CT, and all-cause mortality.

RESULTS

Fourteen patients (mean age 62.1 years, range 34-81 years; six males) were included in the study. Sites of occlusion are as follows: M1 middle cerebral artery (MCA, n = 8), M2 MCA (n = 1), proximal basilar artery (n = 1), and distal basilar artery (n = 4). An additional device or technique was used in 9 of 14 patients prior to the use of the retrievable stent. Twelve out of 14 (85.7%) achieved TIMI 2-3 recanalization with 4 of 14 (28.6%) achieving TIMI 3. Eight of 14 (57.1%) patients had modified Rankin Scale (0-2) at 3 months or discharge. ICH on follow-up CT was noted in 28.6% (4 of 14) of patients. All-cause mortality was 2 of 14 (14.3%).

CONCLUSION

Use of a novel self-expanding, fully retrievable stent resulted in fast and very high recanalization rates in acute ischemic strokes with intravascular occlusions.

Treatment of acute ischemic stroke: feasibility of primary or secondary use of a self-expanding stent (Neuroform) during local intra-arterial thrombolysis

INTRODUCTION

We evaluated the feasibility of employing a self-expanding stent (Neuroform) in treatment of acute cerebral ischemia and compared the results of primary and secondary stenting.

METHODS

We analyzed the treatment results of 14 acute ischemic stroke patients (11 men and three women; median age, 65 years) who were treated with Neuroform stents. Seven patients received stent placement for primary recanalization and a further seven for secondary recanalization. We performed between-group comparisons of all of overall procedure duration, recanalization rate immediately after stenting, need for additional measures after stenting, final recanalization rate, occurrence of hemorrhagic transformation, early re-occlusion rate after 24 h, and 3-month functional recovery rate (mRS ≤2).

RESULTS

The median interval from femoral puncture to stent placement was 61.5 min and was significantly shorter in the primary than in the secondary group (55 vs. 95 min, p = 0.004). The recanalization rate immediately after stenting was 42.9% and was greater in the primary than in the secondary group (71.4% vs. 14.3%, p = 0.1). Thirteen patients required various additional therapeutic measures. The final recanalization rate was 78.6%, attributable to improvements in the recanalization rate of the secondary group (71.4% vs. 85.7%). Early hemorrhagic transformation was noted in four patients, but only one patient became symptomatic (symptomatic hemorrhage, 7.1%). Good functional recovery was noted in eight patients (57.1%).

CONCLUSION

Placement of a self-expanding stent during endovascular recanalization of acute ischemic stroke was both feasible and safe. Primary use of this method may enhance early recanalization.