Mechanical Thrombectomy For Acute Stroke Research Articles

Mechanical Thrombectomy in Acute Stroke Due to Carotid Occlusion: A Series of 153 Consecutive Patients

Background: Strokes due to carotid artery occlusion (CAO) are associated with bad clinical prognosis and poor response to intravenous thrombolysis. Several studies in the past have shown the benefits of mechanical thrombectomy (MT) and compared bridging therapy (BT) and primary MT (PMT) in large vessel occlusions, but only a few studies have focused on the specific population of CAO and their response to endovascular treatment. Methods: Retrospective review of patients treated at our center between January 2010 and June 2017 that (1) presented with acute ischemic stroke caused by CAO in the first 4.5 h since symptom onset, and (2) were treated with MT (BT or PMT). Baseline characteristics of the population, comparison between BT and PMT, intrahospital mortality, symptomatic intracranial hemorrhage, and functional outcome were investigated. Results: A total of 153 patients were included. Baseline characteristics: 51.6% were male, and the median age was 71 years. The most frequent risk factor was hypertension (71.9%). The main stroke etiology was atherothrombotic (40.5%). The mean admission National Institute of Health Severity Score (NIHSS) was 19, mean discharge NIHSS was 7. Isolated occlusion of the Extracranial or Intracranial Internal Carotid Artery was the most frequent occlusion location (52.3%). TICI 2b-3 was achieved in 87.6%, intrahospital mortality was 26.8%, symptomatic hemorrhage was 8.5%, and 3 months-modified Rankin Score (mRS) 0–2 was 26.8%. Definitive carotid stenting was needed in 33.3% of the cases. BT versus PMT: Patients treated with PMT presented a higher incidence of atrial fibrillation, anticoagulation, and cardioembolic stroke compared to those treated with BT. No differences in TICI 2b-3, 3 months-mRS or symptomatic hemorrhage were found between both groups. Intrahospital mortality: Poor perfusion-CT mismatch (p = 0.005), isolated Internal carotid artery location (p = 0.024), and symptomatic hemorrhage (p < 0.001) were independent predictors. Symptomatic intracranial hemorrhage: Patients with post-treatment symptomatic hemorrhage had higher intrahospital mortality (p < 0.001) and worse 3 months-mRS (p = 0.033). Functional outcome: Admission NIHSS (p = 0.012) independently predicted 3 months-mRS. Conclusions: In our population, patients with CAO clinically present with severe strokes. Isolated occlusions of the extra- or intracranial segments of the carotid are more frequent than tandem occlusions. Successful recanalization after thrombectomy is achieved in most of the patients, but association with favorable functional outcome is poor. Clinical evolution is similar in patients treated with PMT and BT. Intracranial symptomatic hemorrhage after treatment is associated with higher intrahospital mortality and worse 3 months-mRS. Poor perfusion-CT mismatch, symptomatic hemorrhage, and isolated CAO are independent predictors of intrahospital mortality. Admission NIHSS is an independent predictor of 3 months-mRS.

What is new in stroke imaging and intervention?

Recent updates to guidelines around brain imaging in stroke and transient ischaemic attack are reviewed. A more detailed examination of advanced brain imaging in acute stroke is presented. The recent evidence for endovascular mechanical thrombectomy in acute stroke is reviewed. The implications of delivering thrombectomy are discussed.

Abstract 109: Trevo 2000: Results of the Largest Real-World Registry for Stent Retriever for Acute Ischemic Stroke

Objective: The Trevo Registry was designed to assess real world outcomes of the Trevo Retriever in patients experiencing ischemic stroke. It is the largest prospective study for acute stroke intervention, with 2010 patients enrolled and 90 day outcomes in 1873 patients. The primary endpoint is revascularization status based on post-procedure TICI score and secondary endpoints include 90-day mRS, 90-day mortality, neurological deterioration at 24 hours and device/procedure related adverse events. Methods: The study was a prospective, open-label, consecutive enrollment, multi-center, international registry of patients who underwent mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device. Results: The median NIHSS at admission was 16 (IQR 11-20). Most patients (70.8%) were treated at &lt;= 6 hours from last known normal with a median procedure time of 50 minutes (32-77). The occlusion site was M1 or M2 in 73.9%. General anesthesia was employed in 43.5% of procedures. TICI 2b or 3 revascularization was 92.8% with an average of 1.7 passes with the device. Median NIHSS at 24 hours and discharge was 6 and 4 respectively. Fifty-five percent (55.2%) of patients had mRS ≤2 at 3 months and the overall mortality rate was 13.8%. Patients treated after 8 hours of symptom onset had a 95% revascularization rate and 51.2% mRS ≤2 at 3 months. The symptomatic ICH rate was 1.6%. Patients who met the revised AHA criteria for thrombectomy were found to have 59.5% mRS 0-2 at 90 days. Conclusions: The Trevo Retriever Registry represents the first real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. Due to the fact that this data represents real world use of the Trevo Retriever, (e.g. subjects pre-stroke mRS &gt;1 (29%) and those treated 6-24 hours after stroke symptoms (29%), this data cannot be compared to the results from recent trials with restricted eligibility criteria. Future subgroup analysis of this large cohort will help to identify areas of future research to enhance outcomes further with this treatment modality.

369 The TREVO Registry-Subgroup Analysis, Treatment Beyond 6 Hours

Abstract INTRODUCTION Current randomized trials demonstrating superiority of mechanical thrombectomy for the treatment of acute ischemic stroke for anterior circulation large vessel occlusion, have enrolled patients with symptom onset up to 6 hours. Outcomes of thrombectomy beyond 6 hours have not been well studied. The Trevo Registry is designed to assess real world outcomes of the Trevo Retriever in patients experiencing acute ischemic stroke. Trevo registry has currently enrolled 1431 patients with 90-day outcome data. Outcomes of patients treated beyond 6 hours of symptom onset were studied. METHODS The study design is a prospective, open-label, consecutive enrollment, multi-center, global registry of all patients who undergo mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device. Enrollment is expected to reach 2000 subjects at up to 100 sites. Subgroup analysis of enrolled patients treated beyond 6 hours of symptom onset and with 90-day follow-up was performed. RESULTS &gt;As of March 24, 2017, a total of 1846 total patients were enrolled. Median NIHSS at admission was 15.5 (IQR 11–20). The majority of patients (67.4%) were treated at 6 hours or less from last known normal with a median procedure time of 50 minutes (8-286 minutes). In patients treated after 6 hours from time last known well, the revascularization rate was 93.7% with symptomatic ICH of 1.8% and 90-day mRS = 2 was 51.8%. Subgroup analysis of patients presenting within 6 hours and those presenting beyond 6 hours showed no significant difference in patient demographics or medical comorbidities. There was no difference in complication rate or 90-day outcome between the two groups. CONCLUSION The Trevo Retriever Registry represents the first look at real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. This data represents real world use of the Trevo Retriever including those treated beyond 6 hours after stroke symptoms (33.8%), and this data adds to the results from recent trials with restricted eligibility criteria.

A Comprehensive Nationwide Evaluation of Stroke Centres in the Czech Republic Performing Mechanical Thrombectomy in Acute Stroke in 2016

A Comprehensive Nationwide Evaluation of Stroke Centres in the Czech Republic Performing Mechanical Thrombectomy in Acute Stroke in 2016

Mechanical thrombectomy in acute stroke – Five years of experience in Poland

ObjectivesMechanical thrombectomy (MT) is not reimbursed by the Polish public health system. We present a description of 5 years of experience with MT in acute stroke in Comprehensive Stroke Centers (CSCs) in Poland. Methods and resultsWe retrospectively analyzed the results of a structured questionnaire from 23 out of 25 identified CSCs and 22 data sets that include 61 clinical, radiological and outcome measures. ResultsMost of the CSCs (74%) were founded at University Hospitals and most (65.2%) work round the clock. In 78.3% of them, the working teams are composed of neurologists and neuro-radiologists. All CSCs perform CT and angio-CT before MT. In total 586 patients were subjected to MT and data from 531 of them were analyzed. Mean time laps from stroke onset to groin puncture was 250±99min. 90.3% of the studied patients had MT within 6h from stroke onset; 59.3% of them were treated with IV rt-PA prior to MT; 15.1% had IA rt-PA during MT and 4.7% – emergent stenting of a large vessel. M1 of MCA was occluded in 47.8% of cases. The Solitaire device was used in 53% of cases. Successful recanalization (TICI2b–TICI3) was achieved in 64.6% of cases and 53.4% of patients did not experience hemorrhagic transformation. Clinical improvement on discharge was noticed in 53.7% of cases, futile recanalization – in 30.7%, mRS of 0–2 – in 31.4% and mRS of 6 in 22% of cases. ConclusionOur results can help harmonize standards for MT in Poland according to international guidelines.

Diffusion-weighted imaging or computerized tomography perfusion assessment with clinical mismatch in the triage of wake up and late presenting strokes undergoing neurointervention with Trevo (DAWN) trial methods.

Rationale Efficacy of mechanical thrombectomy for acute stroke due to large vessel occlusion initiated beyond 6 h of time last seen well has not been demonstrated in randomized trials. Aim To establish whether subjects considered to have substantial areas of salvageable brain based on age-adjusted clinical core mismatch who can undergo endovascular treatment within 6-24 h from time last seen well (TLSW) have better outcomes at three months compared to subjects treated with standard medical therapy alone. Age-adjusted clinical core mismatch is defined by age (≤80 or >80 years), baseline National Institutes of Health Stroke Scale (NIHSS) (10-20 or ≥21), and core size (0-20 cm3 in subjects older than 80 and, in subjects younger than 80, 0-30 cm3 with NIHSS 10-20 and 31-50 cm3 with NIHSS ≥21). Design Prospective, randomized, multicenter, Bayesian adaptive-enrichment, open label trial with blinded endpoint assessment. For the purpose of enrolment, ischemic core size will be evaluated by CT perfusion or magnetic resonance imaging-diffusion-weighted imaging measured by automated software (RAPID). Procedures Subjects with acute ischemic stroke due to computed tomography angiography- or magnetic resonance angiogram-proven arterial occlusion of the intracranial internal carotid and/or proximal middle cerebral artery (M1) with age-adjusted clinical core mismatch in whom treatment can be initiated between 6 and 24 h from TSLW are randomized in a 1:1 ratio to receive mechanical embolectomy with the Trevo device or medical management alone. Sequential interim analyses allowing adaptation of enrolment criteria or stopping new enrolment for futility or predicted success will occur in every 50 randomized patients starting at 150 to a maximum of 500 patients. Study outcomes The primary endpoint is the modified Rankin Scale score at 90 days. The primary safety outcome is stroke-related mortality at 90 days. Analysis The primary endpoint, expressed as a utility-weighted modified Rankin Scale score is analyzed using a Bayesian posterior probability with adjustment for ischemic core size. For regulatory reasons, a nested co-primary endpoint analysis was added consisting of the proportion of subjects with modified Rankin Scale 0-2 between the active and control groups also analyzed using a Bayesian model.

Abstract WMP2: Trevo 2000: Real-World Experience in the First 1247 Patients

Objective: The Trevo Registry is designed to assess real world outcomes of the Trevo Retriever in patients experiencing ischemic stroke. This is the largest prospective study for acute stroke intervention, with 1247 patients currently enrolled and 90 day outcomes in 1021 patients. The primary endpoint is revascularization status based on post-procedure TICI score and secondary endpoints include 90-day mRS, 90-day mortality, neurological deterioration at 24 hours and device/procedure related adverse events. Methods: The study is a prospective, open-label, consecutive enrollment, multi-center, international registry of patients undergoing mechanical thrombectomy for acute stroke using the Trevo stent retriever as the initial device. Enrollment is expected to reach 2000 subjects at up to 100 sites. Results: As of August 13, 2016 a total of 1247 patients were enrolled. The median NIHSS at admission was 16 (IQR 11-20). Most patients (66.2%) were treated at &gt;/= 6 hours from last known normal with a median procedure time of 50 minutes (32-77). The occlusion site was M1 or M2 in 74.5%. General anesthesia was employed in 46.6% of procedures. TICI 2b or 3 revascularization was 92.8% with an average of 1.6 passes with the device. Median NIHSS at 24 hours and discharge was 6 and 4 respectively. Fifty-five percent of patients had mRS ≤2 at 3 months and the overall mortality rate was 15.4%. Patients treated after 8 hours of symptom onset had a 94.9% revascularization rate and 52.8% mRS ≤2 at 3 months. The symptomatic ICH rate was 1.2%. Patients who met the revised AHA criteria for thrombectomy were found to have 58.4% mRS 0-2 at 90 days. Conclusions: The Trevo Retriever Registry represents the first real world data with stent retriever use in the era of clinical trials showing the overwhelming benefit of stent retrievers to treat acute ischemic stroke. Due to the fact that this data represents real world use of the Trevo Retriever, (e.g. subjects pre-stroke mRS &gt;1 (16.5%) and those treated 6-24 hours after stroke symptoms (33.8%), this data cannot be compared to the results from recent trials with restricted eligibility criteria. Future subgroup analysis of this large cohort will help to identify areas of future research to enhance outcomes further with this treatment modality.

The Evolution of Mechanical Thrombectomy for Acute Stroke.

The natural history of an acute ischemic stroke from a large vessel occlusion (LVO) is poor and has long challenged stroke therapy. Recently, endovascular therapy has demonstrated superiority to medical management in appropriately selected patients. This advance has revolutionized acute care for LVO and mandates a reevaluation of the entire chain of stroke care delivery, including patient selection, intervention, and post-procedural care. Since endovascular therapy is a therapy specifically targeting LVO, its application should be restricted to those patients only. Clinical and radiologic parameters need to be considered in patient selection. Data supports that all patients over the age of 18years presenting with a National Institutes of Health Stroke Scale (NIHSS) of 6 or greater within 6 hours of symptom onset should be considered for emergent endovascular therapy. Radiologically, those with a LVO of the internal carotid artery (ICA) or middle cerebral artery (MCA) M1 portion, intermediate or good collaterals and without large established infarct should be considered endovascular candidates. Selection beyond these parameters remains an open question and is being actively evaluated. In all cases, revascularization should be attempted with a new generation device (stentriever or direct aspiration), as these techniques are most likely to deliver adequate reperfusion. Post-revascularization, patients are closely monitored in an intensive care setting followed by discharge to rehabilitation, if required, or directly home. Patients should be evaluated in delayed fashion to assess recovery (typically at 3months post-treatment). Ultimately, the poor natural history of ischemic stroke from LVO and the potential significant benefit from endovascular therapy over medical management alone necessitate a national response to ensure we identify and treat all eligible patients as rapidly and effectively as possible.

Emergency Stenting of the Extracranial Internal Carotid Artery in Combination with Anterior Circulation Thrombectomy in Acute Ischemic Stroke: A Retrospective Multicenter Study.

Several small case series reported a favorable clinical outcome for emergency stent placement in the extracranial internal carotid artery combined with mechanical thrombectomy in acute stroke. The rate of postinterventional symptomatic intracranial hemorrhages was reported to be as high as 20%. Therefore, we investigated the safety and efficacy of this technique in a large multicentric cohort. The data bases of 4 German stroke centers were screened for all patients who received emergency stent placement of the extracranial internal carotid artery in combination with mechanical thrombectomy of the anterior circulation between 2007 and 2014. The primary outcome measure was the rate of symptomatic intracranial hemorrhage according to the European Cooperative Acute Stroke Study III criteria; secondary outcome measures included the angiographic revascularization results and clinical outcome. One hundred seventy patients with a median age of 64 years (range, 25-88 years) were treated. They presented after a median of 98 minutes (range, 52-160 minutes) with a median NIHSS score of 15 (range, 12-19). Symptomatic intracranial hemorrhages occurred in 15/170 (9%) patients; there was no statistically significant difference among groups pertaining to age, sex, intravenous rtPA, procedural timings, and the rate of successful recanalization. In 130/170 (77%) patients, a TICI score of ≥ 2b could be achieved. The in-hospital mortality rate was 19%, and 36% of patients had a favorable outcome at follow-up. Emergency stent placement in the extracranial internal carotid artery in combination with anterior circulation thrombectomy is effective and safe. It is not associated with a significantly higher risk of symptomatic intracranial hemorrhage compared with published series for mechanical thrombectomy alone.

Mechanical thrombectomy for acute ischemic stroke with cerebral microbleeds

BackgroundThe influence of cerebral microbleeds (CMBs) on post-thrombolytic hemorrhagic transformation (HT) in patients with acute ischemic stroke remains controversial.ObjectiveTo investigate the association of CMBs with HT and clinical outcomes among...

Endothelial trauma from mechanical thrombectomy in acute stroke: in vitro live-cell platform with animal validation.

Endovascular thrombectomy has shown promise for the treatment of acute strokes resulting from large-vessel occlusion. Reperfusion-related injury may contribute to the observed decoupling of angiographic and clinical outcomes. Iatrogenic disruption of the endothelium during thrombectomy is potentially a key mediator of this process that requires further study. An in vitro live-cell platform was developed to study the effect of various commercially available endovascular devices on the endothelium. In vivo validation was performed using porcine subjects. This novel in vitro platform permitted high-resolution quantification and characterization of the pattern and timing of endothelial-cell injury among endovascular thrombectomy devices and vessel diameters. Thrombectomy devices displayed heterogeneous effects on the endothelium; the device performance assessed in vitro was substantiated by in vivo findings. In vitro live-cell artificial vessel modeling enables a detailed study of the endothelium after thrombectomy and may contribute to future device design. Large animal studies confirm the relevance of this in vitro system to investigate endothelial physiology. This artificial vessel model may represent a practical, scalable, and physiologically relevant system to assess new endovascular technologies.

Abstract W MP12: Sequential NIHSS Change is a Better Predictor of Good Functional Outcome than Pre-Treatment Neurological Status after Mechanical Thrombectomy in Acute Stroke

Purpose: Pre-treatment NIHSS has been shown to be the strongest predictor of outcome after endovascular therapy in acute ischemic stroke. However, it is not clear if sequential changes in NIHSS scores have any predictive value after mechanical thrombectomy cases. Methods: Prospective (Pivotal N=119, PICS N=219, START N=124) and retrospective/registry (POST N=95, RetroSTART N=168) cases using the Penumbra System were pooled. All were IV tPA-ineligible or refractory with treatment at &lt;8 h. The association of NIHSS pre- and post-treatment and good clinical outcome (mRS 0-2 at 90 days) was tested. Results: Among 725 patients, mean age was 66 ± 15 and median admission NIHSS score was 17 (IQR 13-21). Median NIHSS improved to 11 at 7 days. NIHSS scores at 7 days showed a stronger relationship with good outcome (correlation 0.84; p&lt;0.001) than baseline (correlation 0.37; p&lt;0.001). Furthermore, serial NIHSS scores (baseline minus 7 day) also predicted good outcome (correlation -0.69; p&lt;0.001). Age (correlation 0.39, p &lt; 0.001), pre-treatment ASPECTS score (correlation -0.19; p &lt; 0.001) but not reperfusion to TIMI 2-3/TICI 2b-3 also demonstrated associations with good outcome. Conclusion: In this pooled Penumbra cohort, post treatment improvement in neurological status significantly predicted good clinical and functional outcomes, independent of reperfusion status.

Adjuvant Tirofiban Injection Through Deployed Solitaire Stent As a Rescue Technique After failed Mechanical Thrombectomy in Acute Stroke.

PurposeWe present our experiences of intra-arterial tirofiban injection through a deployed Solitaire stent as a rescue therapy after failed mechanical thrombectomy in patients with acute ischemic stroke.Materials and MethodsData on 18 patients treated with adjunctive tirofiban injection through a temporarily deployed Solitaire stent after failed mechanical thrombectomy were retrospectively reviewed. Solitaire stent was used as a primary thrombectomy device in 16 of 18 patients. Two patients received manual aspiration thrombectomy initially. If initial mechanical thrombectomy failed, tirofiban was injected intra-arterially through the deployed Solitaire stent and then subsequent Solitaire thrombectomy was performed.ResultsFourteen patients had occlusions in the middle cerebral artery, 2 in the distal internal carotid artery, and 2 in the basilar artery. Successful recanalization was achieved in 14 patients (77.7%) after intra-arterial injection of tirofiban and subsequent Solitaire thrombectomy. Three patients without successful recanalization after rescue method received angioplasty with stenting. Overall, successful recanalization (TICI grades 2b and 3) was achieved in 17 (94.4%) of 18 patients. Periprocedural complications occurred in 5 patients: distal migration of emboli in 5 patients and vessel perforation in 1. Three patients died. Good functional outcome (mRS ≤ 2) was achieved in 9 patients (50.0%) at 3 months.ConclusionRescue intra-arterial injection of tirofiban through a temporarily deployed Solitaire stent may facilitate further recanalization in cases of failed mechanical thrombectomy in patients with acute ischemic stroke.

Acute stroke with concomitant acute myocardial infarction: will you thrombolyse?

Acute stroke with concomitant acute myocardial infarction: will you thrombolyse?

Mechanical thrombectomy for acute stroke in childhood: how much does restricted diffusion matter?

Mechanical thrombectomy holds promise for children with large cerebral arterial occlusions, although there are few reports in this population. We report a case of retrievable stent-assisted mechanical thrombectomy in a...

Double solitaire mechanical thrombectomy in acute stroke: effective rescue strategy for refractory artery occlusions?

Mechanical thrombectomy by using a single stent retriever system has demonstrated high efficacy for recanalization of large-artery occlusions in acute stroke. We aimed to evaluate the feasibility, safety, and efficacy of a novel double Solitaire stent retriever technique as an escalating treatment for occlusions that are refractory to first-line single stent retriever mechanical thrombectomy. All patients treated with the double stent retriever technique by using the Solitaire system were retrospectively selected from 2 large neurointerventional centers. Time to recanalization, angiographic (TICI) and clinical outcomes (mRS), and complications were assessed. Ten patients (median NIHSS score, 16; mean age, 70 years) with MCA M1 segment (n = 5) and terminal ICA (n = 5 including 2 ICA tandem) occlusions were included. Prior single stent retriever mechanical thrombectomy had been performed in 9 patients (median number of passes, 3). Median time to recanalization was 60 minutes (interquartile range, 45-87 minutes). Procedure-related complications occurred in 1 patient; overall mortality was 20%. Recanalization of the target vessel (TICI 2b/3) was achieved in 80%. Good clinical outcome (mRS 0-2) was 50%. In this preliminary feasibility study, the double Solitaire stent retriever technique proved to be an effective method for recanalization of anterior circulation large-artery occlusions refractory to standard stent retriever mechanical thrombectomy.

Carotid Elongation Does Not Affect Angiographic Results of Mechanical Thrombectomy in Acute Stroke.

New techniques have substantially raised recanalization rates of mechanical thrombectomy in acute ischemic stroke in the last few years with initial prospective trials reporting good neurological outcome in up to 58% of the cases. However some recent reports questioning the benefit of endovascular therapy have initiated a discussion about the importance of patient-selection. The purpose of this study was to investigate whether an elongation of the carotid artery affects the angiographic outcome of the recanalization procedure in middle cerebral artery (MCA)-occlusions. The data of 54 patients with occlusions of the M1-segment who underwent mechanical thrombectomy were included. The lengths of the carotid arteries were measured using preinterventional computed tomography (CT)-angiograms. To take individual patient's height into account these lengths were divided by the length of the spine from the tip of the dens to the bottom of the th3 vertebral body (referred to as carotid-to-spine (CS)-Ratio). Angiographic results were scored according to the modified thrombolysis in cerebral infarction (mTICI)-score. Recanalization with mTICI ≥2b was achieved in 83.3%. The mean CS-Ratio was 1.32±0.13. There was a significant correlation between the CS-Ratio and the age of the patients. There were no significant differences in the CS-Ratios of occlusions that were successfully recanalized and those that were not. Neither were there significant correlations of the CS-Ratio and the length of procedure or the number of deployments of the stentretrievers. In this retrospective analysis we report that carotid elongation does not affect angiographic results of mechanical thrombectomy in acute stroke.

Ultrasound guided V3 segment vertebral artery direct percutaneous puncture for basilar artery mechanical thrombectomy in acute stroke: a technical report

A middle aged patient presented with acute ischemic stroke due to basilar artery occlusion. The patient clinically deteriorated despite intravenous thrombolysis and was referred for mechanical thrombectomy. The right vertebral...

Mechanical Thrombectomy in Acute Stroke: Utilization Variances and Impact of Procedural Volume on Inpatient Mortality

An increasing number of endovascular mechanical thrombectomy procedures are being performed for the treatment of acute ischemic stroke. This study examines variances in the allocation of these procedures in the United States at the hospital level. We investigate operative volume across centers performing mechanical revascularization and establish that procedural volume is independently associated with inpatient mortality. Data was collected using the Nationwide Inpatient Sample database in the United States for 2008. Medical centers performing mechanical thrombectomy were identified using International Classification of Diseases, 9th revision codes, and procedural volumes were evaluated according to hospital size, location, control/ownership, geographic characteristics, and teaching status. Inpatient mortality was compared for hospitals performing ≥10 mechanical thrombectomy procedures versus those performing<10 procedures annually. After univariate analysis identified the factors that were significantly related to mortality, multivariable logistic regression was performed to compare mortality outcome by hospital procedure volume independent of covariates. Significant allocation differences existed for mechanical thrombectomy procedures according to hospital size (P<.001), location (P<.0001), control/ownership (P<.0001), geography (P<.05), and teaching status (P<.0001). Substantial procedural volume was independently associated with decreased mortality (P=.0002; odds ratio 0.49) when adjusting for demographic covariates. The number of mechanical thrombectomy procedures performed nationally remains relatively low, with a disproportionate distribution of neurointerventional centers in high-volume, urban teaching hospitals. Procedural volume is associated with mortality in facilities performing mechanical thrombectomy for acute ischemic stroke patients. These results suggest a potential benefit for treatment centralization to facilities with substantial operative volume.