Initial Clinical Experience of Repeat Thrombectomy with a Retrieval Stent (RTRS) with Continuous Proximal Flow Arrest by Balloon Guide Catheter for Acute Intracranial Carotid Occlusion

Background. Balloon guide catheters (BGCs) have good performance in terms of radiological outcomes in acute ischemic thrombectomy. It is not uncommon for BGCs to be blocked by thrombi, especially in cases with acute intracranial internal carotid artery (ICA) occlusion. Our initial experience using repeat thrombectomy with a retrieval stent (RTRS) with continuous proximal flow arrest by BGC for acute intracranial ICA occlusion is presented. Methods. In patients with acute intracranial ICA occlusion treated with RTRS, clinical data, including the National Institutes of Health Stroke Scale (NIHSS) score at admission and modified Rankin Scale (mRS) score at 90 days, and procedural data, including the Extended treatment in Cerebral Infarction (eTICI) score, procedural time, and complications, were analyzed. Results. Thirty-two consecutive patients (12 men (37.5%); mean age: 73 years) were treated with RTRS using a BGC. The median NIHSS score was 19. The median puncture-to-reperfusion time was 46 minutes (range: 22-142 minutes). All patients were successfully revascularized; eTICI 2c or better recanalization was achieved in 30 (93.8%) patients. No procedure-related complications or symptomatic intracranial hemorrhage occurred. Two cases (6.3%) had distal emboli, but none had emboli to the anterior cerebral artery. Fourteen patients (43.8%) achieved a good outcome with an mRS score of 0–2 at 90 days, and 8 patients (25.0%) died. Conclusions. In patients with intracranial ICA occlusion, RTRS with proximal flow arrest by BGC is effective and safe, achieving good clinical and angiographic outcomes. This method may reduce the incidence of distal emboli in thrombectomy with stent retrievers.

The Q and A—The MIVI Q Catheters for Aspiration Thrombectomy—Initial Experience from London

Background: Aspiration thrombectomy is a widely accepted treatment option for large vessel occlusion (LVO). The MIVI aspiration system has a novel design to maximize the lumen size. We present the results of our initial experience with this innovative aspiration thrombectomy system. Materials and Methods: Retrospectively, we reviewed our database to find all cases of LVO treated with the MIVI Q system (February 2019 and July 2020). In addition, we recorded the baseline demographics, NIHSS, ASPECT, mTICI scores, procedural time, complications, and 90 day mRS. Results: Herein, we identified 25 patients with an average age of 65.3 ± 19.3 years (range 19–89), majority of whom were female (n = 14, 56%). The average NIHSS was 16.9 ± 6.7 (range 6–30), and the average CT ASPECT was 7.9 ± 1.4 (range 5–10). The most common clot location was the M1 segment of the MCA (n = 16, 64%). Four of the patients had tandem lesions (16%). The average clot length was 21.7 ± 31 mm (range 2–130 mm). Of the 23 cases where the Q catheter reached the proximal clot face, mTICI ≥ 2b was achieved on the first pass in 11 cases (44%), and at the end of the ‘Q aspiration’ only the procedures with 16 patients achieved mTICI ≥ 2b recanalization (64%). Stent-retrievers were used in 13 cases (52%). At the end of the procedure, 24 patients (96%) achieved mTICI ≥ 2b with 18 patients (72%) achieving mTICI ≥ 2c. The average number of passes with the Q catheter, including when it was used for SOLUMBRA, was 2.1 ± 2.2 (range 1–10). The mean procedure time was 69 ± 32 mins (range 7–116 mins). No complications were associated with the MIVI Q. Conclusions: The MIVI aspiration system is a novel technology with regards to aspiration mechanical thrombectomy. The system is easy to use with early results comparable to other large-bore catheter systems. However, further studies are needed.

Biomarkers of Technical Success After Embolectomy for Acute Stroke

Purpose of the ReviewStent retrievers and large-bore aspiration catheters have doubled substantial reperfusion rates compared to first-generation devices. This has been accompanied by a 3-fold reduction in procedural time to revascularization. To measure future thrombectomy improvements, new benchmarks for technical efficacy are needed. This review summarizes the recent literature concerning biomarkers of procedural success and harm and highlights future directions.Recent FindingsExpanded Treatment in Cerebral Ischemia (eTICI), which incorporates scores for greater levels of reperfusion, improves outcome prediction. Core laboratory–adjudicated studies show that outcomes following eTICI 2c (90%–99% reperfusion) are superior to eTICI 2b50 and nearly equivalent to eTICI 3. Moreover, eTICI 2c improves scale reliability. Studies also confirm the importance of rapid revascularization, whether measured as first pass effect or procedural duration under 30 minutes. Distal embolization is a complication that impedes the extent and speed of revascularization, but few studies have reported its per-pass occurrence. Distal embolization and emboli to new territory should be measured after each thrombectomy maneuver. Collaterals have been shown to be an important modifier of thrombectomy benefit. A drawback of the currently accepted collateral grading scale is that it does not discriminate among the broad spectrum of partial collateralization. Important questions that require investigation include reasons for failed revascularization, the utility of a global Treatment in Cerebral Ischemia scale, and the optimal grading system for vertebrobasilar occlusions.SummaryEmerging data support a lead technical efficacy endpoint that combines the extent and speed of reperfusion. Efforts are needed to better characterize angiographic measures of treatment harm and of collateralization.

Abstract 1122‐000138: De Novo Intracranial Stenosis after Mechanical Thrombectomy with Stent Retrievers

Introduction : Increased vascular damage with the use of stent‐retrievers (SR) has been shown on histopathological analysis of the vascular tissue immediately after mechanical thrombectomy (MT) in animal models. We hypothesized that intraoperative endovascular damage‐intimal injury could result in fibrosis and de novo vascular stenosis (dnVS). The purpose of the study is to identify de novo or worsening intracranial stenosis (wICS) of the treated vessel(s) on patients who underwent MT for the treatment of acute ischemic stroke with SR, on follow‐up vascular imaging (FVI). Methods : This was a retrospective chart review. Patients who underwent MT with SR at two centers from January 2015‐December 2020, who had FVI (CTA, MRA or cerebral angiogram) were included. Patient characteristics, procedural details, timing for FVI and clinical outcomes were collected. Two neuroradiologists reviewed baseline angiograms and FVI to assess for the presence of dnVS or wICS, and graded each stenosis and collateral scores (CS), when stenosis was present. CS were calculated using the multiphase CT angiography collateral score (mCTA). Fischer exact test and Mann‐Whitney U test were used to assess for differences in categorical and continuous variables, respectively. Statistical analysis was performed using SPSS 28.0 (IBM Corp.). Results : Forty‐six patients within this cohort had FVI with 9 patients developing dnVS or wICS in the follow‐up period (19.6%) with a median follow‐up of 113 days. Five of these patients demonstrated a complete occlusion of the target vessel on FVI. Of the remaining 4 patients, mean degree of stenosis was 55%. Only 2 of these patients had underlying stenosis on baseline post‐treatment angiogram: one with 44% stenosis which progressed to 95% in 2 months. Another with mild stenosis that progressed to complete occlusion in 50 days. Adequate revascularization, defined as TICI score >2b was achieved in 88.8% of patients with dnVS or wICS, and in 89.2% of patients with stable FVI. No significant differences were observed in baseline demographics, NIHSS score at presentation or initial ASPECTS. Median number of passes was identical between patients who developed dnVS or wICS (median 1, IQR [1, 2], p = 0.683). Mean CS for dnVS or wICS was 3. No significant differences were observed in discharge or follow‐up NIHSS scores, mRS, mortality, or recurrent stroke or TIA between the two cohorts. Conclusions : MT with SR can be associated with dnVS or wICS in some patients. The number of passes with SR did not seem to have an impact on this. Patients with dnVS or wICS did not have a higher incidence of recurrent stroke or TIA. This could be due to the development of new collaterals in this population. Our study is limited by a small cohort, however, larger studies might be challenging as standardized radiological follow up of these patients has not been implemented.

Abstract 1122‐000170: Stent Retrievers Utilization in Endovascular Treatment of Cerebral Venous Sinus Thrombosis

Introduction : Patients with Cerebral Venous Sinus Thrombosis (CVT) are candidates for Endovascular Mechanical Thrombectomy (EMT) in cases of coma on presentation or clinical deterioration despite anticoagulation. We present two cases of CVT successfully treated with mechanical thrombectomy using Medtronic’s Solitaire Stent retriever. Methods : A retrospective review at a single center university hospital was performed for all cerebral venous sinus thrombosis case log from December 2018 to November 2020. Cases resistant to conventional medical therapy that underwent intrasinus stent retriever endovascular thrombectomy were noted. Results : Case 1: 26 year‐old male with a history of hypertension presented with 2 weeks of headaches, left sided numbness and blurriness of vision. Imaging revealed superior sagittal (SSS) and bilateral transverse sinus thrombosis. Patient was treated with heparin infusion and discharged home on oral apixaban. The following day he presented with new onset expressive aphasia. Imaging was unchanged. Due to worsening symptoms despite anticoagulation, Patient underwent mechanical thrombectomy using a stent retriever. Solitaire 6 × 40 mm stent was advanced and deployed through the microcatheter and retracted in the upper segment of posterior one third of SSS followed by alteplase infusion at 1 mg/hr (25 ml/hr) via Berenstein catheter for the next 36 hours. Intravenous heparin infusion was also started with aPTT goal 60–80. Cerebral angiogram was repeated two days later revealing successful recanalization of previously thrombosed SSS and bilateral transverse sinuses with significantly improved cerebral venous drainage. Patient was transitioned again to oral apixaban. Repeat CTA in 3 months showed significantly improved patency and recanalization. Case 2: A 42 year‐old male with history of ulcerative colitis presented with sudden onset right‐sided hemiparesis and hemisensory loss along with one month of headaches. Presenting NIHSS 14. Imaging revealed SSS thrombosis with thrombosis of the left transverse sinus complicated by left frontal intraparenchymal hemorrhage and subarachnoid hemorrhage. Patient underwent mechanical thrombectomy of SSS using Solitaire 6 × 40mm stent retriever with distal aspiration resulting in improved flow. Clinical course was complicated by seizures and acute respiratory distress syndrome requiring intubation followed by tracheostomy and G‐tube placement which were eventually removed during recovery. Patient was treated with high intensity heparin during his hospitalization and eventually transitioned to apixaban. Work up revealed protein S deficiency. Serial CT angiograms at 6 and 11 months revealed resolution of CVT. NIHSS improved to 1 with mRS of 2. Conclusions : These cases imply that intra‐cerebrovenous sinus mechanical thrombectomy with stent retrievers may be considered in patients with continuing worsening despite optimal medical management.

Abstract 1122‐000112: In Vitro Investigation of Endothelial Injury During Mechanical Thrombectomy for Ischemic Stroke

Introduction : Ischemic stroke (IS) makes up a significant proportion of all strokes, of which large vessel occlusions (LVO) are the most debilitating type. The current clinical standard‐of‐care for IS includes mechanical thrombectomy with stent retrievers. One of the impediments to the success of SR intervention is endothelial injury (EI), which can occur in approximately 30% of cases and impedes vessel reperfusion. Since successful reperfusion of the occluded vessel is instrumental in survival and patient recovery, it is imperative to reduce device injury‐based complications such as vasospasm, and to improve patient outcomes. Methods : In this work, our hypothesis is that EI can be reduced by investigating the mechanisms of stent retriever‐induced injury in vitro using live cell 3D cerebrovascular models. Using true‐scale cerebrovascular phantoms with lumen diameter approximately 4 mm created using 3D printing and PDMS casting, Human Umbilical Vein Endothelial Cells (HUVECs) were seeded on the luminal surface. The in vitro models were coated with fibronectin (density 4 µgrams/cm2) to encourage cell adhesion, and were divided into control and treated samples (n = 3 each). Mechanical thrombectomy was performed using two different clinically used SR (Trevo XP PROVUE 3 × 20 mm and Trevo XP PROVUE 6 × 30 mm) to investigate the extent of stent retriever size on EI on the same diameter lumen. Following thrombectomy, the cerebrovascular models were fixed and stained with immunofluorescent dyes (DAPI, Phalloidin and VE cadherin antibody) and imaged using transmitted light, confocal microscopy and scanning electron microscopy. For quantitative assessment, real time PCR was performed on both control and treated samples. Results : All models were initially confluent and functional, as assessed by immunofluorescent staining (Figure 1 A and B). All treated samples demonstrated EI and endothelial damage, as evidenced by loss of endothelial cell coverage, denuding of the models, stripping / clumping of endothelial cells into non‐physiological three dimensional structures and physical scratching of the in vitro model (Figure 1 C and D). Sizing of stent retriever had a strong influence on the effects on the endothelium, with larger sizes causing more damage. Conclusions : A significant knowledge gap exists in understanding the factors responsible for disruption of the endothelium during mechanical thrombectomy. Using a 3D in vitro platform of cerebrovasculature, we demonstrated that endothelial damage occurs during thrombectomy using stent retrievers. A parameteric investigation is currently ongoing that characterizes the influence of vessel lumen diameter, stent retriever size, number of passes and patient specific vasculature. This work can provide guidelines for optimal stent retriever devices to be used where possible, ultimately reducing EI and improving outcomes of ischemic stroke treatment.

Abstract 1122‐000164: Peri‐embolization Use of Stent Retrievers as a Rescue Tool in Patients with Subarachnoid Hemorrhage

Introduction : Coil migration after endovascular embolization of intracranial aneurysms is one of the periprocedural complications in 2–6% of patients. Stent retriever use is well‐established in treatment of ischemic stroke but has not been well established to address coil retrieval as rescue therapy. We describe three cases with successful removal of migrated coils using stent retrievers. Methods : A retrospective review at a single center university hospital was performed for all Neuro‐endovascular case log from December 2018 to November 2020. Cases of coil migration were reviewed and coil retraction with Stent Retriever with successful coil mass extraction was considered an endpoint. Number of attempts, types of stent retrievers used and time taken for extraction were noted. Results : Case 1: 56‐year‐old female presented with ruptured tri‐lobed 4 × 3 mm Anterior communicating artery aneurysm. Hunt and Hess (H&H) Grade 2. Modified Fisher scale (MFS) 4. Underwent primary coil embolization. Two 2mmx2cm Galaxy Orbit coils were deployed within aneurysm. During deployment of third coil the first two coils displaced out of the aneurysm migrating into left A2 segment. Stryker’s Trevo 3 × 20 mm stent retriever was used for retrieval of coils however they dislodged at the left internal carotid artery (ICA) terminus and migrated distally into the left middle cerebral artery (MCA) M2 superior division. Subsequently, Medtronic’s Solitaire 4 × 40 mm stent retriever was successfully deployed retrieving the migrated coils with full recanalization. Case 2: 64‐year‐old female presented with ruptured 3 × 5.3 mm right posterior communicating artery (Pcom) aneurysm. H&H 5 and MFS 4. Underwent primary coil embolization with placement of Galaxy Orbit 2.5mmx3.5cm coil. On follow up run, coil mass had migrated into the origin of right fetal Pcom. Migrated coil was successfully retrieved using Stryker’s 4 × 40 mm stent retriever with complete recanalization. Case 3: 65‐year‐old female with presented ruptured 8.5 × 6.8 mm right supraclinoid ICA irregular aneurysm. H&H Grade 1. MFS 3. Underwent primary coil embolization with one Galaxy coil (5mm x 10cm) with plan for future flow diversion. Two weeks later, patient experienced acute neurological worsening with new left sided hemiparesis and right gaze deviation. Imaging revealed acute occlusion of right middle cerebral artery M1 segment occlusion with thrombosed migrated coil. Patient underwent retrieval of the coil and superimposed thrombus utilizing Stryker’s Trevo (4*30 mm) stent retriever with resultant full recanalization. Conclusions : These cases demonstrate successful endovascular mechanical removal of migrated coils using stent retrievers. They add to the limited experience of stent retrievers utilization as effective tools for dealing with such complications.

SWIFT DIRECT: Solitaire™ With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire™ Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study

Rationale Whether treatment with intravenous alteplase prior to mechanical thrombectomy (MT) in acute ischemic stroke patients with large vessel occlusion is beneficial remains unclear. Aim To determine whether patients experiencing acute ischemic stroke due to occlusion of the intracranial internal carotid artery or the M1 segment of the middle cerebral artery who are referred to an endovascular stroke center and who are candidates for intravenous alteplase will have non-inferior functional outcome at 90 days when treated with MT alone (direct MT) with stent retrievers compared to patients treated with combined intravenous thrombolysis (IVT) with alteplase plus MT (IVT + MT) with stent retrievers. Sample size To randomize 404 patients 1:1 to direct MT or combined IVT+MT. Methods and design A multicenter, prospective, randomized, open-label, blinded-endpoint (PROBE) trial utilizing an adaptive statistical design. Outcomes The primary efficacy endpoint is functional independence (modified Rankin Scale 0–2) at 90 days. Secondary clinical efficacy outcomes include change in National Institutes of Health Stroke Scale score from baseline to day 1 and health-related quality of life at 90 days. Secondary technical efficacy outcomes include successful reperfusion prior to start of MT and time from randomization to successful reperfusion. Safety outcomes include all serious adverse events, symptomatic intracranial hemorrhage, and mortality up to 90 days. Discussion SWIFT DIRECT will inform physicians whether direct MT in acute ischemic stroke patients with large vessel occlusion is equally or more efficacious than combined treatment with intravenous alteplase and MT. Trial registration ClinicalTrials.gov Identifier: NCT03192332

Trevo 6 × 25mm vs. 4 × 30mm in Mechanical Thrombectomy of M1 LVO

Objectives: Our primary objective was to determine the successful rate of recanalization of M1 large vessel occlusion using either the Trevo 4 × 30 mm or 6 × 25 mm stent during mechanical thrombectomy. Our secondary objectives were to determine differences between the use of these two stent retrievers regarding first-pass effect, periprocedural complications, and mortality in the first 90 days.Methods: This is a retrospective cohort study. Data regarding the stent used, recanalization, number of passes, periprocedural complications, and mortality were determined via our mechanical thrombectomy database along with chart review.Conclusion: When comparing Trevo 4 × 30 mm to 6 × 25 mm stent retrievers used in mechanical thrombectomy for middle cerebral artery large-vessel occlusion causing stroke, there is no statistically significant difference in successful recanalization rates, first-pass effect, perioperative complications, or mortality at 90 days. Studies like this will hopefully lead to further prospective, randomized controlled trials that will help show experts in the field an additional way to perform this procedure effectively and safely.

Use of patient specific 3D printed neurovascular phantoms to simulate mechanical thrombectomy

Background The ability of the patient specific 3D printed neurovascular phantoms to accurately replicate the anatomy and hemodynamics of the chronic neurovascular diseases has been demonstrated by many studies. Acute occurrences, however, may still require further development and investigation and therefore we studied acute ischemic stroke (AIS). The efficacy of endovascular procedures such as mechanical thrombectomy (MT) for the treatment of large vessel occlusion (LVO), can be improved by testing the performance of thrombectomy devices and techniques using patient specific 3D printed neurovascular models. Methods 3D printed phantoms were connected to a flow loop with physiologically relevant flow conditions, including input flow rate and fluid temperature. A simulated blood clot was introduced into the model and placed in the proximal Middle Cerebral Artery (MCA) region. Clot location, composition, length, and arterial angulation were varied and MTs were simulated using stent retrievers. Device placement relative to the clot and the outcome of the thrombectomy were recorded for each situation. Digital subtraction angiograms (DSA) were captured before and after LVO simulation. Recanalization outcome was evaluated using DSA as either ‘no recanalization’ or ‘recanalization’. Forty-two 3DP neurovascular phantom benchtop experiments were performed. Results Clot angulation within the MCA region had the most significant impact on the MT outcome, with a p-value of 0.016. Other factors such as clot location, clot composition, and clot length correlated weakly with the MT outcome. Conclusions This project allowed us to gain knowledge of how such characteristics influence thrombectomy success and can be used in making clinical decisions when planning the procedure and selecting specific thrombectomy tools and approaches.