Background Flow diverters have been widely used in clinical practice for more than a decade. However, most outcome data are limited to 1 year timepoints. This study aims to offer meta-analysis data on long-term (>1 year) safety and effectiveness results for patients with aneurysms treated with flow diverters. Methods PubMed, Web of Science, Embase, and SCOPUS were searched up to February 24, 2022 using the AutoLit platform. We included primary studies assessing the long-term outcomes for flow diverter devices to manage unruptured internal carotid artery aneurysms with a follow-up period of >1 year. The meta-analysis was carried out using Comprehensive Meta-Analysis software (CMA). Results Eleven studies were included in the meta-analysis. The pooled occlusion rates after flow diversion treatment for unruptured intracranial brain aneurysms were 77%, 87.4%, 84.5%, 89.4%, 96% for 1 year, 1–2 years, 2 years, 3 years, and 5 years follow-up, respectively. The in-stent stenosis rate was 4.8% and the retreatment rate for the long-term follow-up period was 5%. No delayed rupture of the aneurysm was reported, and there was one case of delayed ischemic stroke. The sensitivity analysis of the prospective studies showed a complete occlusion rate of 83.5% and 85.2% for 1 and 3 years of follow-up, respectively. Conclusion Flow diverters are safe and effective in short- and long-term follow-up and rarely cause serious delayed side effects.

BACKGROUND AND PURPOSE: Robust wall apposition for flow-diverter stents may be important for endothelialization. Using a large series of experimental aneurysms treated with the Pipeline Embolization Device, the objectives of this study were to 1) assess interobserver agreement for the evaluation of wall apposition on posttreatment DSA and evaluate its association with aneurysm occlusion, and 2) measure the relationship between wall apposition assessed with histology and aneurysm occlusion rate after treatment. MATERIALS AND METHODS: Saccular aneurysms were created in 41 rabbits and treated with the Pipeline Embolization Device. DSA was performed just after the deployment of the device and at follow-up. Three investigators independently graded wall apposition on posttreatment DSA as good or poor. A histopathologist blinded to the angiographic results graded the wall apposition on histologic samples. We examined the correlation between angiographic occlusion and wall apposition with histology and angiography. RESULTS: Wall apposition evaluated on histology was strongly associated with saccular aneurysm occlusion. Sensitivity and specificity of wall apposition to predict complete occlusion at follow-up were 76.9% and 84.0%, respectively, with an overall accuracy of 81.6%. In this experimental study, DSA was suboptimal to assess flow-diverter apposition, with moderate interobserver agreement and low accuracy. CONCLUSIONS: Good wall apposition is strongly associated with complete occlusion after flow-diverter therapy. In this study, DSA was suboptimal for assessing wall apposition of flow-diverter stents. These findings suggest that improved tools for assessing flow diverter–stent wall apposition are highly relevant.

Background First pass effect (FPE) in mechanical thrombectomy is thought to be associated with good clinical outcomes. Objective To determine FPE rates as a function of thrombectomy technique and to compare clinical outcomes between patients with and without FPE. Methods In July 2020, a literature search on FPE (defined as modified Thrombolysis in Cerebral Infarction (TICI) 2c–3 after a single pass) and modified FPE (mFPE, defined as TICI 2b–3 after a single pass) and mechanical thrombectomy for stroke was performed. Using a random-effects meta-analysis, we evaluated the following outcomes for both FPE and mFPE: overall rates, rates by thrombectomy technique, rates of good neurologic outcome (modified Rankin Scale score ≤2 at day 90), mortality, and symptomatic intracerebral hemorrhage (sICH) rate. Results Sixty-seven studies comprising 16 870 patients were included. Overall rates of FPE and mFPE were 28% and 45%, respectively. Thrombectomy techniques shared similar FPE (p=0.17) and mFPE (p=0.20) rates. Higher odds of good neurologic outcome were found when we compared FPE with non-FPE (56% vs 41%, OR=1.78) and mFPE with non-mFPE (57% vs 44%, OR=1.73). FPE had a lower mortality rate (17% vs 25%, OR=0.62) than non-FPE. FPE and mFPE were not associated with lower sICH rate compared with non-FPE and non-mFPE (4% vs 18%, OR=0.41 for FPE; 5% vs 7%, OR=0.98 for mFPE). Conclusions Our findings suggest that approximately one-third of patients achieve FPE and around half of patients achieve mFPE, with equivalent results throughout thrombectomy techniques. FPE and mFPE are associated with better clinical outcomes.

Background: We retrospectively evaluated the composition of retrieved clots from ischemic stroke patients to study the association between histological composition and stroke etiologyMethods: Consecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using martius scarlet blue (MSB) staining, and quantification for red blood cells (RBCs), white blood cells (WBCs), fibrin and platelets was performed using Orbit Image Software. A Wilcoxon test was used for continuous variables and χ²test for categorical variables.Results: 1350 patients were included in this study. The overall rate of Thrombolysis In Cerebral Infarction (TICI) 2c/3 was 68%. 501 patients received tissue plasminogen activator (tPA) (37%). 267 patients (20%) had a large artery atherosclerosis (LAA) source, 662 (49%) a cardioembolic (CE) source, 301 (22%) were cryptogenic, and the remainder had other identifiable sources including hypercoagulable state or dissection. LAA thrombi had a higher mean RBC density (46±23% vs 42±22%, p=0.01) and a lower platelet density (24±18% vs 27±18%, p=0.03) than CE thrombi. Clots from dissection patients had the highest mean RBC density (50±24%) while clots from patients with a hypercoagulable state had the lowest mean RBC density (26±21%).Conclusions: Our study found statistically significant but clinically insignificant differences between clots of CE and LAA etiologies. Future studies should emphasize molecular, proteomic and immunohistochemical characteristics to determine links between clot composition and etiology.

Background Early neurological improvement (ENI) is a potential predictor for 90-day outcomes following mechanical thrombectomy for acute ischemic stroke (AIS). We performed a systematic review and meta-analysis to better understand whether ENI can be used as a surrogate for long-term outcomes following mechanical thrombectomy for AIS. Methods Following the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, MEDLINE, and Embase. ENI definition, including timing and degree of improvement on the National Institutes of Health Stroke Scale (NIHSS), was catalogued for each included study. Outcomes of interest included 90-day modified Rankin Scale (mRS) 0–2, symptomatic intracranial hemorrhage (sICH), and mortality. We calculated pooled ORs and their corresponding 95% confidence intervals (CI) for all definitions of ENI. Results We included nine studies with 2355 patients in our analysis. ENI definitions included improvement in NIHSS of 8 points, 4 points, 12%, and 30% or greater. There was a significant association between ENI and mRS 0–2 rates (OR 8.62, 95% CI 4.86 to 15.29; p<0.001). Significance of the association was maintained across all definitions (p<0.001). Moreover, achieving ENI was a significant predictor of reduced odds for reported sICH rates (OR 0.11, 95% CI 0.06 to 0.21; p<0.001). There was a significant association between ENI and reduction in mortality rates (OR 0.09, 95% CI 0.05 to 0.15; p<0.001). Conclusions Broadly defined, ENI is a promising predictor of good functional outcome at 90 days and is associated with lower rates of mortality and sICH.

Most studies define the technical success of endovascular thrombectomy (EVT) as a Thrombolysis in Cerebral Infarction (TICI) revascularization grade of 2b or higher. However, growing evidence suggests that TICI 3 is the best angiographic predictor of improved functional outcomes. To assess the association between successful TICI revascularization grades and functional independence at 90 days, we performed a systematic review and network meta-analysis of thrombectomy studies that reported TICI scores and functional outcomes, measured by the modified Rankin Scale, using the semi-automated AutoLit software platform. Forty studies with 8691 patients were included in the quantitative synthesis. Across TICI, modified TICI (mTICI), and expanded TICI (eTICI), the highest rate of good functional outcomes was observed in patients with TICI 3 recanalization, followed by those with TICI 2c and TICI 2b recanalization, respectively. Rates of good functional outcomes were similar among patients with either TICI 2c or TICI 3 grades. On further sensitivity analysis of the eTICI scale, the rates of good functional outcomes were equivalent between eTICI 2b50 and eTICI 2b67 (OR 0.81, 95% CI 0.52 to 1.25). We conclude that near complete or complete revascularization (TICI 2c/3) is associated with higher rates of functional outcomes after EVT.