Mechanical Thrombectomy in Patients With Milder Strokes and Large Vessel Occlusions A Multicenter Matched Analysis

Background and Purpose-We aimed to describe the safety and efficacy of immediate mechanical thrombectomy (MT) in patients with large vessel occlusions and low National Institutes of Health Stroke Scale (NIHSS) versus best medical management. Methods-Patients from prospectively collected databases of 6 international comprehensive stroke centers with large vessel occlusions (distal intracranial internal carotid, middle cerebral artery-M1 and M2 segments, or basilar artery with or without tandem occlusions) and NIHSS 0 to 5 were identified and divided into 2 groups for analysis: immediate MT or initial best medical management which included rescue MT after neurological deterioration (best medical management-MT). Uni- and multivariate analyses and patient-level matching for age, baseline NIHSS, and occlusion site were performed to compare baseline and outcome variables across the 2 groups. The primary outcome was defined as good outcome (modified Rankin Scale score, 0-2) at day 90. Safety outcome was symptomatic intracranial hemorrhage as defined by the ECASS (European Cooperative Acute Stroke Study) II and mortality at day 90. Results: Compared with best medical management-MT (n=220), patients with immediate MT (n=80) were younger (65.3 +/- 13.5 versus 69.5 +/- 14.1;P=0.021), had more often atrial fibrillation (44.8% versus 28.2%;P=0.012), higher baseline NIHSS (4, 0-5 versus 3, 0-5;P=0.005), higher Alberta Stroke Program Early CT Score (10, 7-10 versus 10, 5-10;P=0.023), more middle cerebral artery-M1, and less middle cerebral artery-M2 (41.3% versus 21.9% and 28.8% versus 49.3%;P=0.016) occlusions. The adjusted odds ratio for good outcome was 3.1 (95% CI, 1.4-6.9) favoring immediate MT. In the matched analysis, there was a 14.4% absolute difference in good outcome (84.4% versus 70.1%;P=0.03) at day 90 favoring immediate MT. There were no safety concerns. Conclusions: Our retrospective, pilot analysis suggests that immediate thrombectomy in large vessel occlusions patients with low NIHSS on presentation may be safe and has the potential to result in improved outcomes. Randomized clinical trials are warranted to establish the optimal management for this patient population

Abstract Number ‐ 232: Carotid Webs as an Under‐Reported Etiology of Acute Ischemic Stroke – Current Diagnostic Challenges

Introduction Carotid webs are anatomical variants in the internal carotid artery vasculature that predispose patients to stroke. As of now, optimal treatment has yet to be established given the lack of large, randomized trials. Part of this stems from the fact that carotid webs remain under‐recognized sources of ischemic stroke despite a high rate of reoccurrence. Herein, we aim to shed light on the diagnosis with our respective center’s experience as well as discuss diagnostic challenges associated with carotid webs. Methods We present a case of a 40‐year‐old male with no past medical history who presented to our center after having developed sudden onset left sided weakness and sensory loss, a left homonymous hemianopia, and dysarthria. Vessel imaging confirmed a right middle cerebral artery occlusion, specifically in the M2 segment, in the setting of a right carotid web. Results Once intracerebral hemorrhage was ruled out, tissue plasminogen activator was administered, with improvement in neurologic exam. Mechanical thrombectomy was thus deferred. Review of the MRI brain showed that in addition to an infarct in the right subinsular white matter region, there were scattered multifocal right hemispheric acute to early subacute infarcts raising concern for an underlying embolic etiology. While the right M2 occlusion looked like it had mainly resolved, a new focal non‐occlusive intraluminal thrombus was found in the right carotid bulb on CTA, MRA, and carotid ultrasound, just distal to a small transverse extraluminal carotid web (Figure 1). The decision was made to take the patient for right carotid stenting given that the carotid web served as a high‐risk lesion. A stent was placed in the right carotid artery with no complications, and the patient was continued on dual antiplatelet therapy. Upon being seen in outpatient clinic after discharge, patient had NIHSS score of 0, with no residual deficits, and was continued on DAPT and a statin for secondary stroke prevention. Conclusions Knowing that patients with carotid webs are at increased risk for stroke, recognition and accurate diagnosis of webs is crucial for appropriate treatment. Diagnostic challenges of carotid webs should be highlighted to prevent misdiagnosis. These include heightened awareness of the patient population that is most at risk, radiographic mimics, location of the lesion as a confounder, and rule out of other stroke etiologies. Prompt recognition of this high‐risk vascular lesion using multiple imaging modalities at different time points during the patient’s admission allowed for treatment of the underlying etiology of his stroke. By increasing awareness on the appropriate diagnostic approach for carotid webs, more information can be garnered to elucidate optimal treatment strategies

Abstract 1122‐000047: Machine Learning to Predict Stroke Outcomes after Mechanical Thrombectomy

Introduction: Prognostication is an integral part of clinical decision‐making in stroke care. Machine learning (ML) methods have gained increasing popularity in the medical field due to their flexibility and high performance. Using a large comprehensive stroke center registry, we sought to apply various ML techniques for 90‐day stroke outcome predictions after thrombectomy. Methods: We used individual patient data from our prospectively collected thrombectomy database between 09/2010 and 03/2020. Patients with anterior circulation strokes (Internal Carotid Artery, Middle Cerebral Artery M1, M2, or M3 segments and Anterior Cerebral Artery) and complete records were included. Our primary outcome was 90‐day functional independence (defined as modified Rankin Scale score 0–2). Pre‐ and post‐procedure models were developed. Four known ML algorithms (support vector machine, random forest, gradient boosting, and artificial neural network) were implemented using a 70/30 training‐test data split and 10‐fold cross‐validation on the training data for model calibration. Discriminative performance was evaluated using the area under the receiver operator characteristics curve (AUC) metric. Results: Among 1248 patients with anterior circulation large vessel occlusion stroke undergoing thrombectomy during the study period, 1020 had complete records and were included in the analysis. In the training data (n = 714), 49.3% of the patients achieved independence at 90‐days. Fifteen baseline clinical, laboratory and neuroimaging features were used to develop the pre‐procedural models, with four additional parameters included in the post‐procedure models. For the preprocedural models, the highest AUC was 0.797 (95%CI [0.75‐ 0.85]) for the gradient boosting model. Similarly, the same ML technique performed best on post‐procedural data and had an improved discriminative performance compared to the pre‐procedure model with an AUC of 0.82 (95%CI [0.77‐ 0.87]). Conclusions: Our pre‐and post‐procedural models reliably estimated outcomes in stroke patients undergoing thrombectomy. They represent a step forward in creating simple and efficient prognostication tools to aid treatment decision‐making. A web‐based platform and related mobile app are underway

Association Between Stroke Presentation During Off‐Hours and Mechanical Thrombectomy

Background Access to mechanical thrombectomy (MT) in the United States remains limited. Given potential staffing challenges, we hypothesized that access to thrombectomy would be worse off hours. Methods We used 2016 to 2018 all‐payer claims data from all nonfederal emergency departments and acute care hospitals across 11 US states encompassing 80 million residents. Using recorded arrival times, hospital presentation was classified as on hours if it fell between 8:00 a.m. and 6:00 p.m. on weekdays and as off hours otherwise. We examined the association between off‐hours arrival and MT using multiple adjusted logistic regression models. In a subset of patients with available National Institutes of Health Stroke Scale data, we performed a sensitivity analysis limited to patients who presented to a thrombectomy hub with a probable large‐vessel occlusion, defined as a documented National Institutes of Health Stroke Scale score ≥12, and underwent intravenous thrombolysis. Similar analyses were performed to assess MT odds during extreme off hours, defined as midnight to 6:00 a.m., compared to 8:00 a.m. to 2:00 p.m. Results Among 169 199 patients with ischemic stroke, the 82 784 (48.9%) who presented during off hours more often presented to thrombectomy hubs and teaching hospitals and more often received intravenous thrombolysis. Among 31 148 patients with documented National Institutes of Health Stroke Scale scores, those presenting off hours had higher scores (4 [interquartile range, 2–10] versus 2 [interquartile range, 1–9]; P<0.001). There were no differences between groups in rates of MT (3.4% on hours versus 3.5% off hours; P=0.25). In adjusted models, off‐hours presentation was not significantly associated with lower odds of MT (odds ratio [OR], 0.94; [95% CI, 0.85–1.03]). Our findings were similar in a sensitivity analysis limited to patients with a probable large‐vessel occlusion who initially presented to a thrombectomy hub and underwent intravenous thrombolysis (OR, 0.87; [95% CI, 0.69–1.09]). Extreme off‐hours presentation was associated with a lower likelihood of MT (OR, 0.83; [95% CI, 0.75–0.93]). Conclusion In a large, population‐based sample of ischemic stroke patients across the United States, the odds of MT were similar during on and off hours. Extreme off hours seem to be associated with decreased access to treatment

Abstract WP1: Thrombectomy Outcomes in Acute Ischemic Stroke due to Middle Cerebral Artery M2 Occlusion with Stent-Retriever, Aspiration, MERCI: Multi-Center Experience

Introduction: Recent trials demonstrated that mechanical thrombectomy improve functional outcome in anterior circulation acute ischemic stroke (AIS) due to emergent large vessel occlusion (ELVO) of the middle cerebral artery (MCA) M1 segment. However, such data regarding AIS due to MCA M2 segment ELVO is limited. Analysis of the STAR, SWIFT, and SWIFT-PRIME trials found thrombectomy in MCA M2 occlusion to be feasible in achieving successful reperfusion. The most optimal technique and/or device used for such reperfusion is not clearly defined. We aim to compare the outcome for the contemporary techniques and devices used for thrombectomy of AIS patients due to MCA M2 ELVO. Methods: A retrospective review of AIS patients with MCA M2 ELVO receiving thrombectomy from three tertiary care academic medical centers was conducted. Thrombectomy technique and thrombectomy device utilized were recorded. Outcomes were successful angiographic reperfusion (TICI ≥2b), favorable modified Rankin Scale (mRS≤2) at discharge and at 90 days, and rate of symptomatic intracerebral hemorrhage (sICH). Results: From October 1999 through June 2016, 253 AIS patients underwent thrombectomy for MCA M2 ELVO. Thrombectomy methods utilized were Stent-retriever (n=118), Aspiration only [manual or Penumbra device] (n=83), and MERCI retriever (n=52). Table 1 shows rate of outcomes measured. There was no difference in baseline NIHSS or in stroke onset to groin puncture time. Stent-retriever group showed a significantly higher recanalization rate, lower sICH rate, and favorable 90-day mRS versus Aspiration group or MERCI group, respectively. No significant difference was seen in discharge mRS between the groups. Conclusions: Thrombectomy for AIS patients with MCA M2 ELVO with Stent-retriever appears to be feasible with a significantly higher rate of recanalization, lower sICH rate, and favorable 90-day mRS when compared to Aspiration and MERCI

Clinical Outcomes in Basal Ganglia Strokes Treated With Mechanical Thrombectomy

Background Basal ganglia infarcts are thought to carry worse clinical outcomes compared with other infarct patterns. We aimed to investigate whether pretreatment topographic infarct patterns including complete basal ganglia involvement versus other infarct patterns help predict mechanical thrombectomy outcomes. Methods This was a review of a prospectively collected database of consecutive mechanical thrombectomy patients with anterior circulation large vessel occlusion strokes between January 2014 and November 2018. Patients were categorized into the following 2 groups: (1) total basal ganglia (TBG) strokes defined as infarcts affecting both the caudate and lentiform nuclei regardless of cortical involvement and (2) other infarct patterns. Infarct location was assessed on preprocedure noncontrast computed tomography using an automated software (e‐ASPECTS). Baseline characteristics and outcome measures were compared. Results A total of 1011 patients were analyzed of which 234 (23.12%) had TBG strokes. Patients with TBG strokes were younger (P=0.01); had higher National Institutes of Health Stroke Scale (NIHSS) (P=0.006), lower e‐ASPECTS (P<0.001), and lower systolic blood pressure (P=0.024); and had diabetes less often (P=0.01). Baseline characteristics were otherwise comparable between groups. Involvement of the caudate or lentiform nucleus alone was observed in 237 (30.5%) and 21 (2.7%) patients, respectively, in the other infarct patterns group. No internal capsule involvement was detected in either group. There were no differences in terms of 90‐day functional outcomes whether dichotomized (modified Rankin Scale score≤2: TBG=44.6% versus other=50.1%; P=0.14) or looking at the entire spectrum of the scale (shift analysis; P=0.74). However, TBG strokes had significantly higher rates of any parenchymal hematomas (15.4% versus 8.2%; P=0.001), an association that held true in multivariable analysis (adjusted odds ratio, 2.57 [95% CI, 1.41–4.62]; P=0.002). Conclusions Despite increased rates of hemorrhagic transformation, ganglionic infarcts carry similar functional outcomes after mechanical thrombectomy compared with other stroke patterns

Thrombectomy Outcomes in Acute Ischemic Stroke due to Middle Cerebral Artery M2 Occlusion with Stent Retriever versus Aspiration: A Multicenter Experience

To examine outcomes for thrombectomy devices used for treatment of acute ischemic stroke (AIS) with middle cerebral artery (MCA) M2 segment emergent large vessel occlusion (ELVO) as the optimal device for such reperfusion is not clearly defined. A retrospective cohort study of consecutive AIS patients with MCA M2 ELVO undergoing thrombectomy from 3 academic medical centers was conducted from October 1999 through June 2016. The patients were divided based on the device utilized. Multivariate analysis of associations between devices (stent retriever or aspiration only [manual or pump aspiration system]) was performed. Primary outcomes were good recanalization (i.e., modified thrombolysis in cerebral infarction score ≥2b) and a favorable modified Rankin scale (mRS) score (i.e. ≤2). The secondary outcome was symptomatic intracerebral hemorrhage (sICH). A total of 197 AIS patients underwent MCA M2 ELVO thrombectomy with either a stent retriever ( = 120) or aspiration only ( = 77). The aspiration-only group utilized either manual ( = 38) or pump aspiration ( = 39). Utilization of a stent retriever over manual aspiration is independently associated with higher odds of a favorable mRS score (OR = 3.2; 95% CI 1.02-9.7) and lower odds of sICH (OR = 0.09; 95% CI 0.03-0.31). Utilization of a stent retriever over a pump aspiration system is independently associated with higher odds of good recanalization (OR = 3.8; 95% CI 1.5-9.6). Utilization of a newer-generation pump aspiration catheter compared to a stent retriever resulted in similar rates of favorable mRS scores, sICH, successful recanalization, and mortality. Utilization of a newer-generation pump aspiration catheter compared to a stent retriever resulted in similar outcomes, but worse outcomes were seen with the manual aspiration technique. These findings need to be confirmed with a large randomized trial utilizing stent retrievers and newer-generation pump aspiration systems