Flow Re-Direction Endoluminal Device Research Articles

Lower-Ischemic-Risk Profile of Coated Flow Redirection Endoluminal Device X Compared With Uncoated Flow Redirection Endoluminal Device Flow Diverter in the Treatment of Unruptured Intracranial Aneurysms.

Flow Redirection Endoluminal Device (FRED) X is a new generation flow diverter with an antithrombotic surface coating. This study compares the procedural safety and short-term efficacy of FRED X with its uncoated predecessor, the FRED. Patients treated with FRED and FRED X devices for unruptured aneurysms between 2013 and 2023 at 3 neurovascular centers were retrospectively reviewed. The procedural ischemic event rate was the safety end point, and the complete aneurysm occlusion rate at 1 year was the efficacy end point. Multivariable regression adjustment and 1:1 propensity score matching were performed to control for potential confounding. The FRED X group (137 patients) had a higher prevalence of recurrent and bifurcation aneurysms and fewer aneurysms with branch involvement than the FRED X group (156 patients). The ischemic event rate was lower in FRED X (1/156 [0.6%]) than in FRED (7/137 [5.1%]), which was significant after multivariable adjustment (odds ratio: 8.8, 95% CI: 1.1-72.7, P = .04), and tended to be significant in the propensity score analysis (P = .07). Morbidity was comparable between FRED (2.2%) and FRED X (0%, P = .10). The complete occlusion rates of FRED vs FRED X were 73/117 (62.4%) vs 39/54 (72.2%) aneurysms at 6 months (P = .21) and 52/74 (70.3%) vs 27/37 (73.0%) at 12 months (P = .77). Hemorrhagic complications, in-stent stenosis, and clinical events during follow-up and retreatments were not significantly different between groups. This study indicates an improved ischemic risk profile of FRED X while maintaining a favorable efficacy profile, warranting further study and translation into clinical use.

Safety and efficacy of flow redirection endoluminal device (FRED) for treatment of intracranial aneurysm; A systematic review and meta-analysis.

Previous research has shown promising results for treating intracranial aneurysms (IAs) with a flow redirection endoluminal device (FRED). In this systematic review and meta-analysis, we aimed to assess the safety and efficacy of this device by providing pooled estimates using the data from previous studies. A systematic literature search of Web of Sciences, PubMed, Scopus, and Embase was performed until October 8th, 2023. After selecting the final articles, relevant data were extracted. Parameters relating to safety and efficacy were pooled using STATA software. Heterogeneity was assessed using I-squared and Cochran's Q. Funnel plots and Egger's regression methods were used to evaluate publication bias. Sensitivity analysis was also performed using the leave-one-out method. The data of 37 studies were used for meta-analysis. The rates of immediate adequate occlusion and complete occlusion were 0.51 (95% CI: 0.31-0.71) and 0.34 (95% CI: 0.16-0.53), respectively, while the rates of the adequate and complete occlusion at the latest follow-up were 0.90 (95% CI: 0.84-0.94) and 0.75 (95% CI: 0.65-0.84), respectively. The periprocedural complications rate was 0.04 (95% CI: 0.03-0.06), and the overall complications rate was 0.12 (95% CI: 0.09-0.15). The rate of good functional outcome was 0.99 (95% CI: 0.99-1.00) and the successful implantation rate was 1.00 (95% CI: 1.00-1.00). There was substantial heterogeneity among the reports for most of the evaluated parameters. FRED had high safety and efficacy in treating IAs, as evidenced by its high occlusion and low complication rates.

Comparison of pipeline embolization device and flow redirection endoluminal device in the treatment of intracranial aneurysms: A systematic review and meta-analysis.

Advancements in flow diversion technology have revolutionized the treatment of intracranial aneurysms. The pipeline embolization device (PED) and the flow redirection endoluminal device (FRED) have emerged as prominent tools in this field. This study aims to compare the safety and efficacy profiles of PED and FRED in the treatment of intracranial aneurysms. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive literature search was conducted across PubMed, Web of Science, and Scopus databases. Studies comparing PED and FRED were included and data extraction focused on study characteristics, patient demographics, and clinical and radiological outcomes. Primary outcomes were favorable outcomes, described as modified Rankin scale (mRS) 0-2 score, and complete/near-complete occlusion, while secondary outcomes included retreatment rate and thromboembolic and hemorrhagic complications. Five studies, comprising 1238 patients, were included. No significant differences were found between PED and FRED in terms of complete occlusion at 6 months and 1 year, complete/near-complete occlusion at the last follow up, retreatment rates, and thromboembolic, in-stent thrombosis and hemorrhagic complications. However, FRED was significantly associated with higher favorable outcomes compared to PED (odds ratio: 0.37; confidence interval: 0.17 to 0.81; p = 0.01). This study showed that both PED and FRED had comparable rates of complete occlusion, retreatment and complications, and FRED also demonstrated a higher likelihood of achieving favorable outcomes. The study underscores the need for further research with larger cohorts and longer follow up to consolidate these findings.

Comparative Efficacy of Flow Diverter Devices in the Treatment of Carotid Sidewall Intracranial Aneurysms: aRetrospective, Multicenter Study.

The comparative efficacy and safety of first-generation flow diverters (FDs), Pipeline Embolization Device (PED) (Medtronic, Irvine, California), Silk (Balt Extrusion, Montmorency, France), Flow Re-direction Endoluminal Device (FRED) (Microvention, Tustin, California), and Surpass Streamline (Stryker Neurovascular, Fremont, California), is not directly established and largely inferred. This study aimed to compare the efficacy of different FDs in treating sidewall ICA intracranial aneurysms. We conducted aretrospective review of prospectively maintained databases from eighteen academic institutions from 2009-2016, comprising 444 patients treated with one of four devices for sidewall ICA aneurysms. Data on demographics, aneurysm characteristics, treatment outcomes, and complications were analyzed. Angiographic and clinical outcomes were assessed using various imaging modalities and modified Rankin Scale (mRS). Propensity score weighting was employed to balance confounding variables. The data analysis used Kaplan-Meier curves, logistic regression, and Cox proportional-hazards regression. While there were no significant differences in retreatment rates, functional outcomes (mRS 0-1), and thromboembolic complications between the four devices, the probability of achieving adequate occlusion at the last follow-up was highest in Surpass device (HR: 4.59; CI: 2.75-7.66, p < 0.001), followed by FRED (HR: 2.23; CI: 1.44-3.46, p < 0.001), PED (HR: 1.72; CI: 1.10-2.70, p = 0.018), and Silk (HR: 1.0ref. standard). The only hemorrhagic complications were with Surpass (1%). All the first-generation devices achieved good clinical outcomes and retreatment rates in treating ICA sidewall aneurysms. Prospective studies are needed to explore the nuanced differences between these devices in the long term.

It Is Necessary to Pay Attention to Where the Pcom Originate from the Aneurysm to Treat with FD.

Objective With the expansion of indications of flow diverter (FD) for cerebral aneurysms, FD placement for posterior communicating artery (Pcom) aneurysms has been approved. However, it is controversial whether Pcom aneurysms should be treated with FD or not. In this study, we report the outcome of FD treatment for Pcom aneurysms in Japan. Materials and Methods We retrospectively analyzed 36 patients with 38 aneurysms treated with FD placement for Pcom aneurysms between 2015 and 2021 in our hospital. We divided our cases into complete occlusion (CO) and non-CO groups. And we extracted contributing factors to CO using multivariate analysis. We also compared the complications rate among the three types of FDs. Results CO was obtained in 29 cases (79.3%), and complications were observed in 3 cases (7.9%). Multivariate analysis revealed that the type of Pcom branch from the aneurysmal dome was a significant factor contributing to CO (odds ratio: 0.0052, 95% confidence interval 0.000048-0.584, p = 0.029). In terms of complications, complication rate was significantly higher in the Flow-Redirection Endoluminal Device (FRED) group ( p = 0.0491). Conclusion The outcome for Pcom aneurysms treated by FD was acceptable. When treating, we must pay attention to where Pcom originates. Achieving CO with FD is difficult for aneurysms where the Pcom branches from the dome. Furthermore, when treating Pcom aneurysms with FRED, it is necessary to be careful about thromboembolic complications.

FRED X flow diverter for the treatment of intracranial aneurysms: Two-center experience and mini-review of the literature.

The flow re-direction endoluminal device (FRED) is a safe and effective treatment option for intracranial aneurysms. The novel FRED X features an antithrombotic surface coating ("X Technology") on an otherwise unmodified stent design. This two-center study evaluates the clinical safety and efficacy of FRED X and compares it to the literature. Consecutive patients treated between 2020 and 2023 were retrospectively reviewed for aneurysm characteristics, procedural details and complications, and angiographic outcomes. A mini-review of the literature for FRED X clinical trials was performed and results were pooled using a random effects model. Thirty-four patients (mean age 56 years) were treated for 34 aneurysms. The mean aneurysm size was 7.7 ± 5.0 mm, 7 (21%) were ruptured, 6 (18%) were recurrent after previous treatment, 11 (32.3%) were located in the posterior circulation, and 4 (12.5%) had non-saccular morphology. All procedures were technically successful and no balloon angioplasty was required. There was 1 (2.9%) symptomatic complication (a transient ischemic attack) and no procedural morbidity or mortality. Technical asymptomatic events included 1 procedural stent occlusion that was reopened with thrombectomy and 3 cases of vasospasm. Complete and adequate occlusion rates were 68% (19/28) and 89% (25/28) at a mean follow-up time of 6 months, respectively. The results of this study are comparable to previous FRED X studies. The results demonstrate a high feasibility and procedural safety of the FRED X with adequate mid-term occlusion rates. Long-term and comparative studies are needed to evaluate the full potential of the FRED X.

Long-term Follow-up After Aneurysm Treatment with the Flow Redirection Endoluminal Device (FRED) Flow Diverter

IntroductionThis study focuses on long-term outcomes after aneurysm treatment with either the Flow Re-Direction Endoluminal Device (FRED) or the FRED Jr. to investigate the durability of treatment effect and long-term complications.MethodsThis study is based on a retrospective analysis of a prospectively maintained patient data base. Patients treated with either FRED or FRED Jr. between 2013 and 2017 at our institution, and thus a possibility for ≥ 5 years of follow-up, were included. Aneurysm occlusion rates, recurrence rates, modified Rankin scale score shifts to baseline, and delayed complications were assessed.ResultsIn this study 68 patients with 84 aneurysms had long-term follow-up with a mean duration of 57.3 months and 44 patients harboring 52 aneurysms had a follow-up ≥ 5 years with a mean follow-up period of 69.2 months. Complete occlusion was reached in 77.4% at 2 years and increased to 84.9% when the latest available imaging result was considered. Younger age and the absence of branch involvement were predictors for aneurysm occlusion in linear regression analysis. After the 2‑year threshold, there were 3 reported symptomatic non-serious adverse events. Of these, one patient had a minor stroke, one a transitory ischemic attack and one had persistent mass effect symptoms due to a giant aneurysm, none of these resulted in subsequent neurological disability.ConclusionThis long-term follow-up study demonstrates that the FRED and FRED Jr. are safe and effective for the treatment of cerebral aneurysms in the long term, with high rates of complete occlusion and low rates of delayed adverse events.

Ghost twisting of the dual-layer flow-diverting stent.

The twisting phenomenon of the flow diverter stents rarely occurs, but it recently became relatively well-recognized. There have been few reports on single-layer flow diverters only. The Flow Redirection Endoluminal Device (FRED) (MicroVention, Tustin, California) has a unique design characterized by a braided dual-layer self-expanding stent. There have been no reports on the twisting phenomenon of FRED. This study reports two cases of acute in-stent blood flow disturbances after the deployment of FRED in a patient with intracranial aneurysms associated with "ghost twisting." In this phenomenon, the inner layer does not expand with the coning deformation, even though the outer layer is fully open. This was confirmed through high-resolution cone-beam computed tomography, but not conventional angiography. The two cases were successfully treated using balloon angioplasty and showed favorable outcomes. The structural issue of "ghost twisting" was a possible underlying factor for the ischemic complications associated with FRED deployment.

Low-Profile Visualized Intraluminal Support Junior Flow-Diversion Properties Used for Stabilization of a Superior Cerebellar Artery Pseudoaneurysm

Pseudoaneurysms of the posterior circulation pose a unique management challenge. The fragile nature of the pseudoaneurysm wall presents a high risk of rupture and demands treatment. Small vasculature, particularly distal in the posterior circulation, can preclude management with traditional flow diverters, where the alternative of vessel sacrifice is unacceptable. Small stents can have flow-diversion properties and can be used in these high-risk, difficult-to-access aneurysms. We describe a 40-year-old woman presenting with a ruptured dissecting right superior cerebellar artery pseudoaneurysm after minor trauma. Given the aneurysm's small size and morphology, it was not amenable to coiling and parent vessel sacrifice was potentially morbid. The pseudoaneurysm was initially stabilized with a Low-Profile Visualized Intraluminal Support Junior (LVIS Jr.) stent due to its reported flow-diverting properties. At six-month follow-up the pseudoaneurysm was stable and the vasospasm had resolved. At this point, definitive treatment with a "FRED Jr." (Flow Re-Direction Endoluminal Device Junior) flow diverter was pursued. Complete obliteration of the pseudoaneurysm was seen at 12 months' follow-up after staged treatment. Due to the unique challenges associated with ruptured pseudoaneurysms located on small-caliber vessels, the options for definitive treatment are limited. The small size of the LVIS Jr. stent and its flow-diverting properties make it a practical treatment option in a difficult situation. This case report provides further support for the flow-diverting properties of the LVIS Jr. and its potential application in the treatment of ruptured pseudoaneurysms in small-caliber intracranial vessels.

Comparison of pipeline embolization device, flow re-direction endoluminal device and surpass flow diverters in the treatment of intracerebral aneurysms.

The use of flow diversion for the treatment of intracranial aneurysms has gained broad acceptance. Three flow-diverting stents are approved by the Food and Drug Administration for use in the United States. We sought to compare the outcomes and safety profiles between the three devices at our institution. A retrospective review of aneurysms treated with pipeline embolization device (PED), flow re-direction endoluminal device (FRED), and SURPASS was performed for aneurysms treated between 2018 and 2022 at our institution. The study cohort consisted of 142 patients. Precisely, 86 aneurysms were treated with a pipeline, 33 aneurysms were treated with FRED, and 23 aneurysms were treated with SURPASS. The 1-year complete occlusion rates were 59.4%, 60%, and 65%, respectively (0.91). Linear regression models found that only adjunctive coiling predicted aneurysm occlusion at 6 months (p = 0.02), but this effect was lost at 1 year and beyond. There was no significant difference in acute thrombotic or acute hemorrhagic complications between the three cohorts. There was a higher rate of delayed hemorrhagic complications in the SURPASS cohort (10%) compared to the PED (1.3%) and FRED (0%) cohorts (p = 0.04). There was also a higher rate of in-stent stenosis in the SURPASS cohort (20%) compared to the PED (5%) and FRED (3.1%) cohorts (p < 0.01). Treatment with PED, FRED, and SURPASS all resulted in similar complete occlusion rates at 6 months and 1 year. SURPASS was associated with higher in-stent stenosis as well as delayed hemorrhagic complications. Additional future studies evaluating the newest generation of flow-diverting stents with long-term follow-up will be necessary to make any definitive conclusions.

Use of a flow diverter in a small-caliber end artery anterior choroidal dissecting pseudoaneurysm: illustrative case.

Anterior choroidal artery (AChA) fusiform aneurysms are exceedingly rare and associated with high rebleeding and mortality rates. Their difficult anatomy comes with a broad range of treatment options, including bypass, stent-assisted coiling, and flow diversion. Currently, flow diverters are approved for large-caliber internal carotid artery segment aneurysms. However, many institutions have expanded their use to distal small-caliber vessels, which raises questions regarding device sizing and long-term patency. The authors present a dissecting distal AChA fusiform pseudoaneurysm treated successfully with flow diversion. A 40-year-old woman with monoclonal gammopathy of unknown significance, lichen sclerosis, and an unspecified connective tissue disease presented with diffuse subarachnoid hemorrhage. She had a dissecting, 5 × 3-mm, left AChA pseudoaneurysm 4 mm distal to the origin of the vessel. A 2.5-mm flow redirection endoluminal device was deployed. There were no procedural complications. A 6-month cerebral angiogram showed device patency and no pseudoaneurysm remnant. These results were maintained at 1 year as seen on head magnetic resonance angiography. Flow diversion is a successful and safe therapeutic intervention for challenging intracranial aneurysms originating from small-caliber vessels supplying eloquent vascular territories.

Flow Diverter Treatment Using a Flow Re-Direction Endoluminal Device for Unruptured Intracranial Vertebral Artery Dissecting Aneurysm: Single-Center Case Series and Technical Considerations.

This study aimed to evaluate the effectiveness, safety, and technical considerations of flow diverter (FD) treatment using a Flow Re-direction Endoluminal Device (FRED) for unruptured intracranial vertebral artery dissecting aneurysms (VADAs). We conducted a retrospective study of 23 patients with unruptured intracranial VADAs who underwent FD treatment using a FRED between June 2017 and August 2021. Symptoms, imaging findings, treatment strategies, and angiographic and clinical outcomes were evaluated. Dissections were categorized according to the dominance of the VA in which they occurred: dominant VA, co-dominant VA, and non-dominant VA. All patients successfully underwent FD treatment with either a FRED (n=11) or FRED Jr. (n=12). Complete occlusion rates were 78.3% at 6-month follow-up magnetic resonance angiography and 91.3% at 12-month. There were no instances of complications, recurrence, or retreatment during a median follow-up of 20 months. Dissections occurred in the dominant VA in 3 cases (13.0%), the co-dominant VA in 13 cases (56.5%), and the non-dominant VA in 7 cases (30.4%). Intimal flap and true lumen stenosis were observed in 39.1% and 30.4% of cases, respectively. Four cases required a bilateral VA approach due to technical difficulties, all in the non-dominant VA. Flow diversion treatment using a FRED for unruptured intracranial VADAs proved feasible and safe, yielding satisfactory occlusion rates. Technical challenges were more likely in lesions involving non-dominant VAs in the acute or subacute stage, mainly due to associated intraluminal lesions compromising the arterial lumen.

291 Internal Carotid Artery Aneurysms Treated with Fred, Silk, and Pipeline Stents: A Cross-Sectional Study

Abstract Objective Intracranial aneurysms (IAs) are present in ∼ 2 to 5% of the population. Several treatments have been used, including endovascular options such as flow diverter devices (FDDs). The present study retrospectively analyzed the effectiveness of three FDDs in the treatment of 291 aneurysms in the internal carotid artery. The devices analyzed were the flow-redirection endoluminal device (FRED), the SILK Embolization Device and the PIPELINE Embolization Device (PED). Method This is a cross-sectional study which evaluates the outcome of control arteriography. The O'Kelly-Marotta (OKM) Scale was used to assess the degree of filling and flow stasis in the aneurysm 12 months after surgery. Results Conjoining the result of the three devices, most aneurysms (87.9%) were from the classification C-D, that is, they presented complete or almost complete aneurysmal occlusion. However, 6.6% did not obtain aneurysm occlusion, so they were classified as belonging to group A. In group B, a subocclusion was presented in 5.5%. In addition, by analyzing individually the result of each device, there was a bigger proportion of those classified in the group A among those who used SILK and in the group C-D among those who used FRED. Regarding complications, 10 cases were found, corresponding to 4.23% of all 236 patients. Therefore, four of these patients had complications when treated with PED; this proportion is higher than expected concerning the other groups. Conclusion The three devices are safe choices. Particularly, the FRED was found to be the most effective in treating internal carotid artery aneurysms.

Difference in the cumulative incidence of aneurysmal occlusion by Flow Re-direction Endoluminal Device and Pipeline Embolization Device in the treatment of unruptured internal carotid artery aneurysms: a propensity score-matched cohort study.

The introduction of flow diverters (FDs) has represented a paradigm shift in the management of unruptured cerebral aneurysms (UCA). Flow Re-direction Endoluminal Devices (FREDs) and Pipeline Embolization Devices (PEDs) have gained widespread popularity. We aimed to investigate the cumulative incidence of aneurysm occlusion. A total of 195 patients with 199 UCAs were analyzed retrospectively. The outcomes were aneurysmal occlusion during the follow-up, a modified Rankin Scale score of 0-2 at 90days, additional treatment, major stroke, and steno-occlusive events of FD. Propensity score-matched analysis was performed, controlling for age, sex, aneurysmal size, and location of the internal carotid artery (ICA) aneurysm. Non-ICA aneurysms were excluded from matching. During the follow-up period (median, 366days), complete and satisfactory aneurysmal occlusions were observed in 128 (68%) and 148 (78%) of 189 UCAs in the unmatched cohort. The 142 (71 each) propensity score-matched cohort was complied. The FRED group had a higher cumulative incidence of ICA aneurysm occlusion (complete: HR 2.7, 95% CI 1.4-5.1, p = 0.0025; satisfactory: HR 2.4, 95% CI 1.1-5.2, p = 0.025). The proportion of additional treatment was significantly smaller in the FRED group (OR 0.077, 95% CI 0.010-0.57, p = 0.0007). Other outcomes showed no significant differences. Propensity score-matched analysis indicated that FRED might have a higher cumulative incidence of aneurysmal occlusion in the treatment of unruptured ICA aneurysms. Whether a cumulative incidence of aneurysmal occlusion may differ by the type of FDs warrants further investigation.

Usefulness of silent magnetic resonance angiography for intracranial aneurysms treated with a flow re-direction endoluminal device.

Flow re-direction endoluminal device (FRED) is a novel dual-layer flow-diverting stent to treat cerebral aneurysms with high obliteration rates, however, it induces inevitable metal-related artifacts. We compared silent magnetic resonance angiography (MRA), a new MRA method using ultra-short time of echo and arterial spin-labeling, with conventional time-of-flight (TOF)-MRA for imaging aneurysms treated using FRED. Between May 2020 and September 2022, 16 patients with unruptured internal carotid aneurysms treated using FRED simultaneously underwent silent MRA and TOF-MRA after treatment, with 36 follow-up sessions in total. Two observers independently graded the quality of intra-aneurysmal flow and stented parent arteries under both types of MRA from 1 (not visible) to 4 (nearly equal to digital subtraction angiography [DSA]), with reference to DSA images as a standard criterion. The mean scores for intra-aneurysmal flow and stented parent arteries were significantly better for silent MRA (3.93 ± 0.21 and 3.82 ± 0.32, respectively) than for TOF-MRA (2.08 ± 0.99 and 1.92 ± 0.79, respectively) (P < 0.01). Intermodality agreements for intra-aneurysmal flow and stented parent arteries were 0.87 and 0.90, respectively. Silent MRA is superior to TOF-MRA for assessing patients treated with FRED, with potential as an alternative imaging modality to DSA.

FRED Jr stent for acute flow diversion in ruptured cerebral aneurysms arising from small-caliber vessels: a clinical case series.

Treatment of ruptured aneurysms arising from small-caliber (< 2.5 mm) or distal vessels beyond the circle of Willis is considered challenging with all treatment modalities. Recently, the Flow Re-Direction Endoluminal Device Junior (FRED Jr) stent, designed for flow diversion in small arteries, was approved in the United States for the treatment of nonruptured aneurysms. Here, the authors report their experience using this device in the setting of subarachnoid hemorrhage (SAH). Clinical and radiological records of patients sustaining SAH treated with a FRED Jr stent between June 2020 and October 2022 were reviewed. Treatment course, including antiplatelet therapy, external ventricular drain (EVD) management, and vasospasm, and clinical outcomes were analyzed. Angiographic results were assessed according to the O'Kelly-Marotta (OKM) grading scale. Nine patients at a median age of 62 (range 27-75) years were included. The median Hunt and Hess grade was II (IQR I) and the median modified Fisher grade was 4 (IQR 1). Aneurysm morphology types included saccular (6 patients), blister (1 patient), and dissecting (2 patients), and the aneurysms were located at the anterior communicating artery complex (n = 3) at the A2/A3 (n = 3), M2/M3 (n = 1), V4 (n = 1), and P2 (n = 1) arterial segments. All stents were deployed successfully with no intraprocedural complications. Postoperatively, no rebleeding events were encountered. Vasospasm therapy was initiated in 6 patients, and no symptomatic EVD-related hematomas were observed. Postoperative ischemic events were encountered in 2 patients. The median 3-month modified Rankin Scale score was 2 (IQR 1) for the 7 surviving patients, and 3-month radiographic follow-up revealed OKM grade D in 4 of 7 patients. Flow diversion using the FRED Jr stent is feasible as a potential treatment strategy for acutely ruptured aneurysms arising from small-caliber vessels. The complication profile reported in this series is comparable to those of historical microsurgical cohorts, and effective protection was conferred by this treatment modality. Therefore, our small cohort provides a glimpse into a new tool for successfully achieving acute flow diversion for this subset of difficult-to-treat aneurysms.

396 North American Multicenter Experience of the Flow-Redirection Endoluminal Device (FRED) in the Treatment of Intracranial Aneurysms

INTRODUCTION: Flow-diverters have revolutionized the endovascular treatment of intracranial aneurysms. The evidence on the Flow Re-direction Endoluminal Device (FRED) is limited compared to some counterparts that have been available for clinical use longer. METHODS: Between June 2020 and November 2021, consecutive cerebral aneurysms treated using FRED were included across 7 North American centers. Data collected included patient demographics, aneurysm characteristics, peri-procedural and long-term complications, modified Rankin Scale (mRS) scores, and radiologic follow-up. RESULTS: 133 aneurysms in 116 patients treated in 123 FRED deployment procedures were included. One hundred twenty-six aneurysms (94.7%) were unruptured, 117 (88.0%) were saccular, and 123 (92.5%) aneurysms were located in the anterior circulation. Mean aneurysm maximal width and neck sizes were 7.2 mm and 4.1 mm, respectively. Successful FRED deployment was achieved in 122 (99.2%) procedures. Radiologic follow-up was available for 101 aneurysms at a median duration of 7.0 months. At the last follow-up, complete occlusion was observed in 55.4%, residual neck in 8.9%, and filling aneurysm in 35.6%. On multivariate regression analysis, age (OR = 0.93; p = 0.001) and aneurysm neck size (OR = 0.83; p = 0.048) negatively correlated with odds of complete occlusion. The retreatment rate was 6/124 (4.8%). The overall complication rate was 31/116 (26.7%). Parent vessel occlusion, covered branch occlusion, and in-stent stenosis were detected in 9/99 (9.1%), 6/63 (9.5%), and 15/99 (15.2%) of the cases, respectively. FRED-related, symptomatic, thromboembolic, and hemorrhagic complication rates were 22.4%, 12.9%, 6.9%, and 0.9% respectively. The morbidity rate was 10/116 (8.6%). CONCLUSIONS: As the first large-scale North American multi-center FRED experience, this study confirms FRED’s ease of successful deployment but suggests a lower efficacy and higher rate of complications compared to previous European and South American FRED studies and other flow diverting devices.

Safety and efficacy of flow diverter stents in the treatment of middle cerebral artery aneurysms: a single-center experience and follow-up data

This study aims to evaluate the safety and efficacy of flow diverters (FDs) in the treatment of middle cerebral artery (MCA) aneurysms and share the follow-up (F/U) results. The treatment and F/U results of 76 MCA aneurysms treated with the flow re-direction endoluminal device (FRED), FRED Jr., and pipeline embolization device (PED) FD stents were evaluated retrospectively. The aneurysm occlusion rates were compared between FDs, and the integrated and jailed branches were evaluated through follow-ups. The oversizing of the stent was compared between occluded/non-occluded aneurysms and integrated branches. The mean F/U duration was 32 ± 6.3 months, and the mean aneurysm diameter was 4.45 mm. A total of 61 (80.3%) aneurysms were wide-necked; 73 (96.1%) were saccular; 52 (68.4%) were located at the M1 segment; and 36 (45.6%) FREDs, 23 (29.1%) FRED Jr.s, and 19 (24.1%) PEDs were used for treatment. The overall occlusion rates for the 6-, 12-, 24-, 36-, and 60-month digital subtraction angiographies were 43.8%, 63.5%, 73.3%, 85.7%, and 87.5% respectively. The last F/U occlusion rates were 67.6% for FRED, 66.7% for PED, and 60.6% for FRED Jr. (P = 0.863). An integrated branch was covered with an FD during the treatment of 63 (82.8%) aneurysms. A total of six (10%) of the integrated branches were occluded without any symptoms at the last F/U appointment. The median oversizing was 0.45 (0-1.30) for occluded aneurysms, and 0.50 (0-1.40) for non-occluded aneurysms (P = 0.323). The median oversizing was 0.70 (0.45-1.10) in occluded integrated branches and 0.50 (0-1.40) in non-occluded branches (P = 0.131). In-stent stenosis was seen in 22 (30.1%) of the stents at the 6-month F/U and in only 2 (4.7%) at the 24-month F/U. Thus, none of the patients had any neurological deficits because of the in-stent stenosis. Severe in-stent stenosis was seen in two stents. MCA aneurysms tend to be complex, with integrated branches and potentially wide necks. FD stents are safe and effective in the treatment of MCA aneurysms, and the patency of the side and jailed branches is preserved in most cases. Higher occlusion and lower in-stent stenosis rates are seen with longer F/U durations.

Abstract Number ‐ 85: Distal Anterior Choroidal Artery Fusiform Aneurysm Successfully Treated with Flow Diversion

Introduction Anterior choroidal artery (AChA) aneurysms account for 3–5% of intracranial aneurysms, and are often saccular, arising at or near the origin of the AChA, with distal lesions being exceedingly rare. Contrary to saccular aneurysms, fusiform aneurysms are associated with a higher risk of rebleeding and mortality due to their formidable anatomy requiring advanced techniques including bypass, stent‐assisted coiling, and, more recently, flow diversion. While flow diverters are becoming more popular, they are currently only approved forinternal carotid artery segment aneurysms. However, many institutions areexpanding their use to more distal and smaller caliber vessels. Herein we present a novel pathology of a dissecting distal AChA fusiform pseudoaneurysm with a small vessel caliber treated successfully with flow diversion. Methods Case presentation and surgical technique. Results We describe a 40‐year‐old woman with monoclonal gammopathy of unknown significance (MGUS), lichen sclerosis, and an unspecified connective tissue disease presenting with diffuse subarachnoid hemorrhage (SAH) (World Federation of Neurosurgical Societies 1; Hunt &amp; Hess scale 2; Modified Fisher Scale 3). A digital subtraction cerebral angiogram revealed a dissecting (5×3 mm) left AChA pseudoaneurysm, 4mm distal to the origin (Figure 1). Flow Redirection Endoluminal Device (FRED Jr, Microvention, CA) (2.5mm 8/13 working/total length) was deployed within the vessel proximal to the aneurysm, preceded by an infusion of 5mg of verapamil to facilitate stent placement (Figure 2). Post procedure, she remained neurologically intact and was discharged on dual antiplatelet therapy (aspirin/ticagrelor). Repeat cerebral angiogram at six months showed patent flow diversion device and no pseudoaneurysm remnant (Figure 3) with a nonfocal physical examination. Conclusions Flow diversion may be a successful, and safe, therapeutic intervention for challenging distal intracranial aneurysms with smaller caliber vessels.

Letter: Commentary: The Pennsylvania Postmarket Multicenter Experience With Flow Redirection Endoluminal Device.

To the Editor: We read with great interest the commentary by Restrepo et al1 discussing our Pennsylvania multicenter postmarket experience with the Flow Redirection Endoluminal Device (FRED) (MicroVention Inc).2 We thank the authors for their interest and the editor for the opportunity to respond. We agree with the authors regarding the multiple important points raised in their commentary. As stated, endoluminal flow diversion (FD) has revolutionized the treatment paradigm of intracranial aneurysms, eventually becoming the standard-of-care treatment for a wide range of lesions, starting from internal carotid artery aneurysms with continuous expansion of its “on-label” utility to multiple “off-label” indications including more distally located and nonsaccular morphologically complex aneurysms.3,4 Despite the initial paradigm-shifting results, improvement of the devices' safety, mostly in decreasing thromboembolic complications, which are the most feared complications of these devices continued to be underway.5,6 These refinements encompassed incessant technical modifications such as introducing new endoluminal devices, establishing intrasaccular flow divertors with the Woven EndoBridge (MicroVention Inc) being the prodigy of these devices,7,8 and surface modifications feature of the existing devices such as Pipeline Embolization Device (PED) (Medtronic) Shield and the FRED-X devices. While large multicenter experiences are currently lacking from the United States, it is worth noting that thromboembolic rates reported from 3 international multicenter studies using the PED Shield (6.4%,9 3.3%,10 2.5%11) were not different from earlier studies using prior PED versions (eg, Prospective Study on Embolization of Intracranial Aneurysms with the Pipeline Device 2.1%12 and IntrePED 3.3%13). Concurrently to the PED Shield, the FRED-X device features a similar nanopolymer surface modification aiming to reduce device thrombogenicity. However, clinical data remain pending to be seen whether there are significant differences in occlusion rates or device's safety profile compared with its predecessor. Multiple questions currently remain in the FD literature; these include the long-term efficacy of the different devices and whether there are any safety/efficacy differences between these devices. A recent systematic review reported a pooled 5-year complete occlusion rate of 96% with most of the literature studies using PED14; however, the analysis did not account for the different FD devices nor particular aneurysmal location, and further studies on this remain warranted. Moreover, limited data are currently known regarding which aneurysm type might be suited for each of those devices and head-to-head comparative performance data of the different devices in certain aneurysms location, for which prospective trials would be needed. Until then, it is likely that operators' technical preferences and personal experiences will continue to be the main impetus for device selection in aneurysms treatment. A recently published survey directed to the US neurointerventional community aimed to elicit common themes in their adoption of the newly introduced devices (ie, Surpass Evolve [Stryker Neurovascular] and FRED devices) to the US market. In this survey, PED was reported as the most common choice for giant aneurysms and ruptured cases (PED Shield in particular), whereas FRED Jr was commonly chosen for distal aneurysms with small parent vessel diameters and Surpass, the device of choice for aneurysms with large parent vessels.15 It has been argued before that the decrease in complications likely stemmed from the device's adequately implied learning curve over time as well as attention to dual antiplatelet therapy and platelet function testing,16 particularly in light of recent level I randomized evidence supporting regular platelet function testing and subsequent medications adjusting in clopidogrel nonresponders or hyporesponders.6 Nonetheless and concurrently to the continuous expansion of the neurointerventional armamentarium with new devices and technologies, a more nuanced approach will likely be needed to identify the most appropriate device with a patient-centered case-specific–based approach.