Aneurysm treatment with WEB in the cumulative population of two prospective, multicenter series: 3-year follow-up

Long-Term Follow-Up of Cerebral Aneurysms Completely Occluded at 6 Months After Intervention with the Woven EndoBridge (WEB) Device: a Retrospective Multicenter Observational Study

The Woven EndoBridge (WEB) device has been widely used to treat intracranial wide neck bifurcation aneurysms. Initial studies have demonstrated that approximately 90% of patients have same or improved long-term aneurysm occlusion after the initial 6-month follow up. The aim of this study is to assess the long-term follow-up in aneurysms that have achieved complete occlusion at 6 months. We also compared the predictive value of different imaging modalities used. This is an analysis of a prospectively maintained database across 13 academic institutions. We included patients with previously untreated cerebral aneurysms embolized using the WEB device who achieved complete occlusion at first follow-up and had available long-term follow-up. A total of 95 patients with a mean age of 61.6 ± 11.9 years were studied. The mean neck diameter and height were 3.9 ± 1.3 mm and 6.0 ± 1.8 mm, respectively. The mean time to first and last follow-up was 5.4 ± 1.8 and 14.1 ± 12.9 months, respectively. Out of all the aneurysms that were completely occluded at 6 months, 84 (90.3%) showed complete occlusion at the final follow-up, and 11(11.5%) patients did not achieve complete occlusion. The positive predictive value (PPV) of complete occlusion at first follow was 88.4%. Importantly, this did not differ between digital subtraction angiography (DSA), magnetic resonance angiography (MRA), or computed tomography angiography (CTA). This study underlines the importance of repeat imaging in patients treated with the WEB device even if complete occlusion is achieved short term. Follow-up can be performed using DSA, MRA or CTA with no difference in positive predictive value.

WEB embolization of very broad-based intracranial aneurysms with a dome-to-neck ratio ≤ 1.1

OBJECTIVE

The Woven EndoBridge (WEB) is a well-studied intrasaccular device for endovascular treatment of wide-necked bifurcation aneurysms. We evaluated the feasibility, safety and efficacy of the WEB for the treatment of very broad-based aneurysms with a dome-to-neck ratio ≤ 1.1.

METHODS

Thirty-four aneurysms treated at three neurovascular centers were retrospectively identified. The mean aneurysm size was 5.5 ± 1.6 mm with a mean neck width of 4.7 ± 1.5 and a mean dome-to-neck ratio of 1.0 ± 0.1. The primary outcome measures were immediate technical treatment success by WEB only, complete or near-complete occlusion at 6-month follow-up and ischemic stroke.

RESULTS

Aneurysm embolization by WEB only was technically feasible in 79.4%. Additional stenting was required in 14.7%. In two aneurysms (5.9%), WEB implantation failed, and the aneurysm was treated by stent- and balloon-assisted coiling, respectively. Thromboembolic events occurred during 5 interventions (14.7%), all of these performed in ruptured aneurysms. One patient (2.9%) remained asymptomatic (follow-up modified Rankin scale [mRS] score: 0), 2 patients (5.9%) had a transient deficit (mRS 0 and 1, respectively), and 2 (5.9%) had a disabling ischemic stroke (mRS 3, respectively). Mid-term angiographic follow-up of 29 patients (4.0 ± 2.6 months, range: 2-9 months) showed complete occlusion (WEB occlusion scale [WOS] A) in 41.4%, near-complete occlusion (WOS B) in 34.5%, a neck remnant (WOS C) in 10.3%, and aneurysm remnants (WOS D) in 13.8%.

CONCLUSIONS

WEB embolization of very broad-necked aneurysms was technically feasible and could be achieved by WEB only in the majority of cases. Considering the challenging anatomy of very broad-based aneurysms, the WEB procedure was reasonably safe and efficient.

Endovascular Treatment of Bifurcation Aneurysms with the Woven EndoBridge: Product Features and Selected Results of Off-Label Use

Treatment for wide-neck bifurcation cerebral aneurysms (WNBAs) is widely performed by endovascular treatment as well as open surgical clipping. However, due to factors such as the shape and size of the aneurysms, as well as the anatomical features of surrounding branch vessels, there are some cases in which simple coiling or conventional adjunctive techniques, such as balloon-assisted or neck bridge stent-assisted coiling, are not sufficient to achieve a satisfactory cure. Against this backdrop, the device known as the Woven EndoBridge (WEB) (MicroVention, Aliso Viejo, CA, USA) was developed and can be deployed directly into the aneurysm for treatment. Over a decade has passed since its development, and it is now used in many countries worldwide. This review provides insights into the evolution of the WEB device from its development to the date of this writing, highlighting the unique features of the device and its treatment indications. Additionally, it discusses the posttreatment course, perspectives on recurrence and retreatment, imaging assessments, and potential off-label use based on numerous studies primarily conducted in Europe and the USA.

Clipping versus coiling: A critical re-examination of a decades old controversy

BACKGROUND

Two major studies, The International Subarachnoid Aneurysm Trial and the Barrow Ruptured Aneurysm Trial, compare the long-term outcomes of clipping and coiling. Although these demonstrated coiling's initial benefits, rebleeding and retreatment rates as well as converging patient outcomes sparked controversy regarding its durability. This article will critically examine the available evidence for and against clipping and coiling of intracranial aneurysms. Critics of endovascular treatment state that the initial benefit seen with endovascular coiling decreases over the duration of follow-up and eventually functional outcomes of both treatment modalities are similar. Combined with the increased rate of retreatment and rebleeding, these trials reveal that coiling is not as durable and not as effective as a long-term treatment compared to clipping. Also, due to the cost of devices following endovascular treatment and prolonged hospitalization following clipping, the financial burden has been considered controversial.

SUMMARY/KEY MESSAGES

Short-term outcomes reveal better morbidity and mortality outcomes following coiling. Despite the higher rates of retreatment and rebleeding with coiling, there was no significant change in functional outcomes following retreatment. Furthermore, examining more recent trials reveals a decreased rate of recurrence and rebleeding with improved technology and expertise. Functional outcomes deteriorate for both cohorts over time while recent results revealed improved long-term cognitive outcomes and levels of health-related quality of life after coiling in comparison to clipping. The expense of longer hospital stays following clipping must be balanced against the expense of endovascular devices in coiling.

A new era in the treatment of wide necked bifurcation aneurysms: Intrasaccular flow disruption

Wide-necked bifurcation aneurysms (WNBAs) are challenging lesions to treat via both open surgical and endovascular techniques. Presently, there are 3 intrasaccular devices available to address many of the limitations of prior techniques, all of which are at different phases of approval for human use around the world. These devices include the Woven EndoBridge (WEB®) made by MicroVention, the Artisse™ Embolization Device made by Medtronic, and the Contour Neurovascular System™ made by Cerus Endovascular. Although heterogenous in design, these devices rely on the principle of using fine mesh overlying the aneurysm neck to slow blood inflow, promoting stagnation and thrombosis that ultimately leads to healing across the neck and exclusion from the circulation. While our understanding improves as long-term occlusion rates from these devices continue to be studied, the safety profiles and short-term success rates demonstrated in recent studies provide optimism for these innovative intrasaccular devices for the treatment of WNBAs. In this paper, we review these 3 intra-saccular flow disruption devices for use in WNBAs and summarize recent literature and studies of their effectiveness and safety.

Woven EndoBridge Device for Unruptured Wide-Neck Bifurcation Aneurysm: A Multicenter 5-Year Follow-up

BACKGROUND AND OBJECTIVES

This multicenter study aimed to assess the safety and efficacy of the Woven EndoBridge (WEB) device for treating unruptured wide-neck intracranial bifurcation aneurysms (WIBAs) with short-, mid-, and long-term follow-ups (FUPs).

METHODS

Consecutive patients with unruptured WIBAs treated with WEB between December 2014 and January 2018 were included. Patient, aneurysm, and device characteristics were collected and analyzed retrospectively. Morbidity and mortality rates were determined by collecting intraprocedural, periprocedural, and delayed complications. Aneurysm occlusion was assessed at 1, 3, and 5 years using a 3-grade scale: complete occlusion, neck remnant, and residual aneurysm. Complete occlusion and neck remnant were considered as adequate occlusion. Patients who received re-treatment were also evaluated.

RESULTS

The study included 104 consecutive patients (55.8% female, mean age 58.6 ± 11.8 years). Aneurysm maximum size, neck, and dome-to-neck mean were, respectively, 6.9 ± 2.1 mm, 4.5 ± 1.2 mm, and 1.4 ± 0.3 mm. One-year FUP was collected for 95 patients, and 3- and 5-year FUPs were collected for 83 patients. Adequate occlusion was observed at 1-year FUP in 90.5% (86/95), 91.6% (76/83) was observed at 3-year FUP, and 92.8% (77/83) at 5-year FUP. None of the aneurysms bled after treatment. During FUP, 6/83 patients (7.2%) were re-treated for residual aneurysm. Morbidity and mortality rates closely related to aneurysm occlusion were 0% (0/104).

CONCLUSION

The WEB device was safe and effective for treating unruptured WIBAs, both in short-term and long-term FUPs.

Management of aneurysmal recurrence after Woven EndoBridge (WEB) treatment

BACKGROUND

Around 10% of Woven EndoBridge device (WEB)-treated intracranial aneurysms will need retreatment, and it is generally believed to be more challenging than retreatment after an initial coiling. We aim to report retreatment strategies and outcomes after initial WEB embolizations.

METHODS

Databases from four treatment centers, containing consecutive aneurysms treated with a WEB between 2013 and 2022, were reviewed. Demographics, aneurysm characteristics, retreatment strategies and outcomes were collected and analyzed.

RESULTS

From a 756 WEB database, 57 aneurysms were included. The global retreatment rate was 7.5% (95% CI 5.6% to 9.4%). The retreatment rate was significantly higher in the ruptured compared with the unruptured population (13% vs 3.9%, respectively, P<0.0001). Aneurysms were retreated on average 21.2 months after the initial WEB treatment (range 4.8-70 months). Surgery was performed in 11% and endovascular treatment in 89% of cases, consisting of flow diversion (48%), stent-assisted coiling (30%), coiling (12%), and second WEB placement (10%). Imaging follow-up was available in 88% of all WEB retreatments (50/57) (average 17 months, 49% digital subtraction angiography), demonstrating complete occlusion in 56% and 'adequate' occlusion in 88%. Morbidity was 5.3% (95% CI 0% to 12.0%) and mortality 0%. No patient experienced rebleeding during the follow-up period.

CONCLUSION

The retreatment rate after an initial WEB treatment seems to compare favorably with that of coiling. Endovascular treatment of recurrence following WEB implantation is feasible in most situations; it generally requires the use of a stent and leads to a high rate of satisfactory occlusion.

Intrasaccular flow disruption for ruptured aneurysms: an international multicenter study

BACKGROUND

The Woven EndoBridge (WEB) device is a novel intrasaccular flow disruptor tailored for bifurcation aneurysms. We aim to describe the degree of aneurysm occlusion at the latest follow-up, and the rate of complications of aneurysms treated with the WEB device stratified according to rupture status.

METHODS

Our data were taken from the WorldWideWeb Consortium, an international multicenter cohort including patients treated with the WEB device. Aneurysms were classified into two groups: ruptured and unruptured. We compared clinical and radiologic outcomes of both groups. Propensity score matching (PSM) was done to match according to age, gender, bifurcation, location, prior treatment, neck, height, dome width, daughter sac, incorporated branch, pretreatment antiplatelets, and last imaging follow-up.

RESULTS

The study included 676 patients with 691 intracranial aneurysms (529 unruptured and 162 ruptured) treated with the WEB device. The PSM analysis had 55 pairs. In both the unmatched (85.8% vs 84.3%, p=0.692) and matched (94.4% vs 83.3%, p=0.066) cohorts there was no significant difference in the adequate occlusion rate at the last follow-up. Likewise, there were no significant differences in both ischemic and hemorrhagic complications between the two groups. There was no documented aneurysm rebleeding after WEB device implantation.

CONCLUSION

There was no significant difference in both the radiologic outcomes and complications between unruptured and ruptured aneurysms. Our findings support the feasibility of treatment of ruptured aneurysms with the WEB device.

Mid-to-long term safety and efficacy of Woven EndoBridge device for Treatment of intracranial wide neck aneurysms: A systematic review and meta-analysis

BACKGROUND

In recent 10 years, Woven EndoBridge(WEB) device has been used as endovascular instrumentation for treating wide neck Bifurcation aneurysms. Its safety and efficacy in the mid-term (6-24 months) and long-term (more than 24 months) follow-up period have yet to be systematically reviewed.

PURPOSE

To evaluate the WEB device safety and efficacy, relevant literature and publications were extensively reviewed, and a meta-analysis was conducted.

DATA RESOURCE

All relevant literature/publications were achieved from Pubmed, Cochrane, Embase, and Web of Science databases.

RESULTS

767 patients that were studied in 13 literature were included. The focus of this review was placed on the clinical and anatomic outcomes. Complete occlusion was achieved in 67.3% (95% CI, 59.0-75.5%) and 69.3% (95% CI, 55.7-82.8%) of the cases at mid- and long-term follow-up. The rate of adequate occlusion was 86.6% (95% CI, 83.0-90.2%) and 90.1% (95% CI, 85.5-94.4%) for the mid and long-term, respectively. 51 patients (8.8%; 95% CI,5.6-11.9%) and 18 (8.1%; 95% CI,0.8-15.5%) received retreatments during mid- and long-term follow-up, respectively. 410 patients from 427 (94.3%; 95% CI, 89.7-98.9%) showed favorable clinical outcomes. The all-cause mortality rate was 3.5% (95% CI, 1.4-5.6%), where only a few cases were related to the WEB implantation. The WEB device deployment was associated with an overall clinical complication rate of 4.1% (95% CI, 2.7-6.6%), 3 hemorrhagic (1.2%; 95% CI, 0.2-2.6%), and 30 thromboembolic (4.0%; 95% CI, 4.0- 6.0%) complications.

CONCLUSIONS

The findings reveal the satisfactory safety and effectiveness of the WEB device for the Treatment of wide-neck aneurysms during mid-to-long-term follow-up, indicating the high potential of the WEB device for wide application.

The Woven EndoBridge (WEB) Device for the Treatment of Intracranial Aneurysms: Ten Years of Lessons Learned and Adjustments in Practice from the WorldWideWEB Consortium

Several studies have shown promising outcomes of the Woven EndoBridge (WEB) device for the treatment of wide-necked intracranial bifurcation aneurysms. This is a multicenter study attempts to explore the changes in trends and treatment outcomes over time for WEB embolization of intracranial aneurysms. The WorldWideWEB consortium is a retrospective multicenter collaboration of data from international centers spanning from January 2011 and June 2021, with no limitations on aneurysm location or rupture status. Both bifurcation and sidewall aneurysms were included. These patients were stratified based on treatment year into five treatment intervals: 2011-2015 (N = 66), 2016-2017 (N = 77), 2018 (N = 66), 2019 (N = 300), and 2020-2021 (N = 173). Patient characteristics and angiographic and clinical outcomes were compared between these time intervals. This study comprised 671 patients (median age 61.4 years; 71.2% female) with 682 intracranial aneurysms. Over time, we observed an increasing tendency to treat patients presenting with ruptured aneurysms and aneurysms with smaller neck, diameter, and dome widths. Furthermore, we observed a trend towards more off-label use of the WEB for sidewall aneurysms and increased adoption of transradial access for WEB deployment. Moreover, the proportion of patients with adequate WEB occlusion immediately and at last follow-up was significantly higher in more recent year cohorts, as well as lower rates of compaction and retreatment. Mortality and complications did not differ over time. This learning curve study suggests improved experience using the WEB for the treatment of intracranial aneurysms and has yielded higher rates of adequate occlusion over time.

A novel intrasaccular aneurysm device with high complete occlusion rate: initial results in a rabbit model

BACKGROUND

Intrasaccular flow-disrupting devices are a safe and effective treatment strategy for intracranial aneurysms. We utilized high-frequency optical coherence tomography (HF-OCT) and digital subtraction angiography (DSA) to evaluate SEAL Arc, a new intrasaccular device, and compare the findings with the well-established Woven EndoBridge (WEB) device in an animal model of saccular aneurysms.

METHODS

In a rabbit model, elastase-induced aneurysms were treated with SEAL Arc (n=11) devices. HF-OCT and DSA were performed after implant and repeated after 12 weeks. Device protrusion and malapposition were assessed at implant time and scored on a binary system. Aneurysm occlusion was assessed at 12 weeks with the WEB Occlusion Scale and dichotomized to complete (A and B) or incomplete (C and D) occlusion. The percentage of neointimal coverage after 12 weeks was quantified using HF-OCT. We compared these data to previously published historical controls treated with the gold-standard WEB device (n=24) in the same model.

RESULTS

Aneurysm size and device placement were not significantly different between the two groups. Complete occlusion was demonstrated in 80% of the SEAL Arc devices, which compared favorably to the 21% of the aneurysms treated with WEB devices (P=0.002). Neointimal coverage across SEAL Arc devices was 86±15% compared with 49±27% for WEB (P=0.001). Protruding devices had significantly less neointimal coverage (P<0.001) as did incompletely occluded aneurysms (P<0.001). Histologically, all aneurysms treated with SEAL Arc devices were completely healed.

CONCLUSION

Complete early aneurysm occlusion was frequently observed in the SEAL Arc treated aneurysms, with significant neointimal coverage after 12 weeks.

Persistent contrast-filling in the woven endobridge device three months after its implantation for cerebral aneurysm: Incidence, predictive factors, and outcome

OBJECTIVE

The Woven EndoBridge (WEB) was developed to treat wide-neck bifurcation intracranial aneurysms. Occasionally, persistent contrast-filling has been observed in the WEB after treatment. The purpose of our study was to investigate its incidence, predictive factors, and clinical impact.

METHODS

All patients treated with the WEB between January 2021 and September 2021 at our institute were reviewed. Age, gender, antiplatelet therapy, and angioarchitecture were compared between the persistent-filling group and the no-filling group at the three-month follow-up angiography.

RESULTS

We included 20 patients with 20 unruptured aneurysms. Ten of the 20 intracranial aneurysms (50 %) showed contrast-filling in the WEB after three months. Two of the 10 had contrast not only inside, but around the device. Statistically significant differences were observed between the persistent-filling group and the no-filling group in neck size (median: 4.5 mm vs. 3.8 mm), deviation of the aneurysm axis from the inlet flow line where the orifice of the bifurcated arteries overlaps (mean: 15.1° vs. 33.0°), and postoperative dual antiplatelet therapy (DAPT) for at least a month (90 % vs. 20 %). One case had additional coil embolization six months after the WEB implantation. Including this case, one year after the treatment or the re-treatment, the filling in the device had disappeared in nine of 10 cases. No bleeding was observed during the mean follow-up period of 24 months.

CONCLUSION

Persistent contrast-filling was associated with postoperative DAPT for at least a month, a wide neck, and less deviation of the aneurysm axis from the inlet flow line. If the contrast-filling is only within the WEB and not between the aneurysmal wall and the WEB, we are not concerned. To further assess the clinical impact of this phenomenon, long-term follow-up will be needed.

Decision-making tree for optimal Woven EndoBridge device sizing with ideal Woven EndoBridge-aneurysm volume (iWAVe) ratio

PURPOSE

Optimal size selection is important for successful Woven EndoBridge (WEB) treatment. Conventional recommendations for WEB sizing based on aneurysm width and height sometimes require device exchange. We aimed to design a novel volume-based parameter, the ideal WEB-aneurysm volume (iWAVe) ratio, for optimal WEB sizing.

METHODS

Consecutive patients who underwent WEB treatment for wide-neck bifurcation aneurysms between January 2021 and May 2022 were retrospectively reviewed. Aneurysm volume was automatically calculated using software. We measured the aneurysm volume based on the expected position of the device within the aneurysm. The WAVe ratio was defined as the ratio of the aneurysm volume to WEB volume. We dichotomized aneurysms treated with a successful sizing or unsuccessful sizing for WEB (successful group and unsuccessful group, respectively).

RESULTS

Thirty-five patients were eligible for study enrollment. Ten patients (28.6%) needed to exchange the WEB on the first attempt and required another WEB on the second attempt resulting in deployment success. Hence, 35 aneurysms were in the successful group and 10 were in the unsuccessful group. The median WAVe ratio was 1.0 (range 0.76-1.31) in the successful group and 1.27 (0.58-1.89) in the unsuccessful group. Using logistic regression, iWAVe ratio was from 0.90-1.16 to secure a >80% probability of success by the 95% lower confidence limit. The sensitivity and specificity of the iWAVe ratio for optimal size selection on the first attempt were 0.60 and 1.00, respectively.

CONCLUSION

Decision-making based on aneurysm width and the iWAVe ratio could promote optimal WEB sizing.

A systematic review of the Woven EndoBridge device-do findings in pre-clinical animal models compare to clinical results?

BACKGROUND

The Woven Endobridge (WEB) is designed to treat intracranial wide-neck bifurcation aneurysms, preventing subarachnoid hemorrhage. The translational value of animal models used for WEB device testing is unknown. With this systematic review, we aim to identify the existing animal models used in testing the WEB device and compare the efficacy and safety outcomes to those of prospective clinical studies.

METHODS

This study was funded by ZonMw: project number 114024133. A comprehensive search was performed in PubMed and in EMBASE via the Ovid interface. The following exclusion criteria were used: 1) not an original full-length research paper, 2) not an in vivo animal study or a human study, 3) no WEB implantation, 4) if in humans: not a prospective study. The SYRCLE risk of bias tool (animal studies) and the Newcastle-Ottawa quality assessment scale for cohort studies (clinical studies) were used to assess risks of bias. A narrative synthesis was performed.

RESULTS

Six animal studies and 17 clinical studies met the inclusion criteria. The rabbit elastase aneurysm model was the only animal model used to assess WEB device performance. Safety outcomes were never reported in animal studies. Efficacy outcomes were more heterogeneous in animal studies than in clinical studies, which could be due to limited external validity of the animal models in terms of aneurysm induction and dimensions. Both animal and clinical studies were predominantly single-arm studies, and were at unclear risk of several types of bias.

CONCLUSIONS

The rabbit elastase aneurysm model was the only pre-clinical animal model used to assess WEB device performance. Safety outcomes were not evaluated in animal studies and could therefore not be compared to clinical outcomes. Efficacy outcomes were more heterogeneous in animal studies than in clinical studies. Future research should focus on improving methodology and reporting in order to draw accurate conclusions on the performance of the WEB device.

Microsurgical clipping as a retreatment strategy for previously ruptured aneurysms treated with the Woven EndoBridge (WEB) device: a mono-institutional case series

BACKGROUND

Since its approval by the US Food and Drug Administration (FDA) in 2018, the flow disruptor Woven EndoBridge (WEB) device has become increasingly popular for the endovascular treatment of unruptured and ruptured cerebral aneurysms. However, the occlusion rates seem rather low and the retreatment rates rather high compared to other treatment methods. For initially ruptured aneurysms, a retreatment rate of 13 % has been reported. A variety of retreatment strategies has been proposed; however, there is a paucity of data concerning microsurgical clipping of WEB-pretreated aneurysms, especially previously ruptured ones. Thus, we present a single-center series of five ruptured aneurysms treated with the WEB device and retreated with microsurgical clipping.

METHODS

A retrospective study including all patients presenting with a ruptured aneurysm undergoing WEB treatment at our institution between 2019 and 2021 was performed. Subsequently, all patients with an aneurysm remnant or recurrence of the target aneurysm retreated with microsurgical clipping were identified.

RESULTS

Overall, five patients with a ruptured aneurysm treated with WEB and retreated with microsurgical clipping were included. Besides one basilar apex aneurysm, all aneurysms were located at the anterior communicating artery (AComA) complex. All aneurysms were wide-necked with a mean dome-to-neck ratio of 1.5. Clipping was feasible and safe in all aneurysms, and complete occlusion was achieved in 4 of 5 aneurysms.

CONCLUSIONS

Microsurgical clipping for initially ruptured WEB-treated aneurysms is a feasible, safe, and effective treatment method in well-selected patients.

Aneurysm Treatment with Woven EndoBridge-17: Angiographic and Clinical Results at 12 Months from a Retrospective, 2-Center Series

BACKGROUND AND PURPOSE

This retrospective, 2-center study investigated the feasibility, safety, and efficacy at 12-month follow-up of the treatment of ruptured, unruptured, and recurrent intracranial aneurysms using the latest generation of the Woven EndoBridge (WEB) device, the WEB-17 system.

MATERIALS AND METHODS

Aneurysms treated with WEB-17 were extracted from the databases of 2 neurovascular centers. Patients, aneurysm characteristics, complications, and clinical and anatomic results were analyzed.

RESULTS

From February 2017 to May 2021, two hundred twelve patients with 233 aneurysms (181/233, 77.7%, unruptured-recurrent, and 52/233, 22.3%, ruptured) were included. High treatment feasibility (95.3%) was reported and was similar in ruptured aneurysms (94.2%) and unruptured-recurrent aneurysms (95.6%) (P = .71) and in typical (95.4%) and atypical (94.7%) locations (P = .70), but it was lower in aneurysms with an angle between the parent artery and main aneurysm axis of ≥45° (90.2%) compared with those with an angle of <45° (97.1%) (P = .03). Global mortality and morbidity were 1.9% and 3.8% at 1 month, respectively, and 4.4% and 1.9% at 12 months, respectively. One-month morbidity (P = .02) and mortality (P = .003) were higher in the ruptured group (10.0% and 8.0%, respectively) compared with unruptured-recurrent group (1.9% and 0.0%, respectively). Overall adequate occlusion (complete occlusion and neck remnant) was 86.3%. The percentage of adequate occlusion was higher (P = .05) in the unruptured-recurrent group (88.5%) compared with the ruptured group (77.5%).

CONCLUSIONS

The WEB-17 system showed high feasibility for ruptured and unruptured aneurysms, typical and atypical locations, and some aneurysms with an angle of ≥45°. As the most recent generation device, the WEB-17 also demonstrates high safety and good efficacy.

Comparative assessment of woven endobridge embolization and standard coil occlusion for the treatment of ruptured basilar tip aneurysms

PURPOSE

Endovascular coil occlusion represents the standard treatment for basilar tip aneurysms. Recently, this role has been rivalled by intrasaccular flow disruptors across numerous centres. We retrospectively compared WEB embolization and coiling for the treatment of ruptured basilar tip aneurysms.

METHODS

Patients treated with WEB or coiling at four neurovascular centres were reviewed. Procedure-related complications, clinical outcome, and angiographic results were retrospectively compared.

RESULTS

The study included 23 patients treated with the WEB (aneurysm size: 6.6 ± 1.9 mm) and 56 by coiling (aneurysm size: 6.7 ± 2.5 mm). Stent-assistance was more often necessary with coiling than with WEB embolization (32% vs. 4%, p = 0.009). A modified Rankin scale score ≤ 2 at discharge had 21 (37.5%) patients in the coiling group and 12 (52.2%) in the WEB group (p = 0.235). Immediate complete and adequate occlusion rates were 52% for the WEB and 87% for coiling. At short-term follow-up, these rates were 87% for the WEB and 72% for coiling, respectively. There was no delayed aneurysm re-bleeding during follow-up.

CONCLUSION

Both coiling and WEB seem to prevent rebleeding in ruptured BTA aneurysms. WEB embolization required less frequently stent-support than coiling, potentially advantageous for SAH patients to avoid anti-platelet therapy in the light of concomitant procedures like ventricular drainage.

Risk factors for recanalization of basilar tip aneurysm after endovascular treatment: a retrospective cohort study

OBJECTIVES

Endovascular treatment (EVT) of basilar tip aneurysms (BTAs) is arduous because of the lesions' angioarchitecture and the relatively high recanalization rate after EVT. In this study, we aimed to report the clinical characteristics of BTAs and evaluate the incidence of and risk factors for recanalization.

METHODS

One hundred twenty-five patients with BTAs (11 ruptured, 114 unruptured) treated with EVT between 2009 and 2019 at one institution were retrospectively reviewed. Among them, 113 patients were included in statistical analyses. The anatomical parameters of the aneurysms and clinical data were analyzed. Univariate (chi-square test and t-test) and multivariate (multiple logistic regression) analyses were performed to identify risk factors for recanalization.

RESULTS

        Recanalization of the BTA occurred in 15 patients (13.3%). One patient (0.9%) was retreated endovascularly. The mean follow-up duration was 49.8 months. Neck size, posterior cerebral artery (PCA) angle, maximum diameter, and the rupture rate differed significantly between the recanalization and non-recanalization groups (P=.007, P<.001, P=.006, and P=.048, respectively). The maximum diameter (odds ratio, 1.483 per mm; 95% confidence interval, 1.145-1.919; P=.003) and PCA angle (odds ratio, 1.020 per degree; 95% confidence interval, 1.001-1.039; P=.036) were independently associated with recanalization.

CONCLUSIONS

Of all investigated BTAs, 96.8% were wide-neck aneurysms. The recanalization rate of BTAs after EVT was 13.3%. The PCA angle and maximal aneurysmal diameter were independently associated with recanalization; no associations were observed regarding vertebral artery dominance or modality of treatment. As such, BTA patients with wide PCA angles should be carefully monitored over time.

Contour-Assisted coiling with jailed microcatheter May result in better occlusion (CoCoJaMBO) in wide-necked intracranial aneurysms: Proof of principle and immediate angiographic results

PURPOSE

Wide-necked bifurcation aneurysms, partially thrombosed, and recurrences of large and giant aneurysms are challenging to treat. We report our preliminary experience with a Contour-assisted coiling technique and discuss the periprocedural safety, feasibility, and effectiveness of the approach.

METHODS

We retrospectively reviewed consecutive patients who received endovascular treatment for intracranial aneurysms with an intra-aneurysmal flow disruptor (Contour) at two neurovascular centres between October 2018 and December 2020 and identified patients treated with a combination of Contour and platinum coils. Clinical and procedural data were recorded.

RESULTS

For this analysis, 8 patients (5 female) aged 60.1  ±  9.2 years on average were identified. Three of 8 aneurysms were associated with previous acute subarachnoid hemorrhage (SAH). The mean average dome height was 12.8  ±  7.6 mm, mean maximum dome width 10.3  ±  5.4 mm, and neck width 5.5  ±  2.5 mm. The mean dome-to-neck ratio was 1.9  ±  1.0. Immediate complete occlusion of the aneurysm was seen in 5 of 8 cases. In one SAH patient, a parent vessel was temporarily occluded but could be reopened rapidly. One device detached prematurely without any sequelae. No other procedural adverse events were recorded.

CONCLUSION

From this initial experience, Contour with adjunctive coiling is a safe and technically feasible method for endovascular treatment of large, wide-necked, partially thrombosed, recurrent, or ruptured bifurcation aneurysms. Further studies with larger numbers of patients and longer follow-up are needed to confirm our results.

Geometry of intracranial aneurysms and of intrasaccular devices may influence aneurysmal occlusion rates after endovascular treatment

INTRODUCTION

The Woven EndoBridge device (WEB) is used to treat wide-neck bifurcation aneurysms. These devices are deployed inside the sac. Therefore, the mesh structure provides apposition with the aneurysm wall and induces aneurysmal thrombosis. The objective of our study was to evaluate the anatomic and device-related parameters and indexes with Computational Fluid Dynamics (CFD) of the intracranial aneurysms before and after WEB simulation and find their relationship to complete occlusion.

MATERIALS AND METHODS

Using the heterogeneous model based on the marching cubes algorithm, we created 3D representations of 27 bifurcated intracranial aneurysms treated with the single-layer WEB device to evaluate anatomic and device-related parameters with CFD.

RESULTS

In our CFD analysis, we observed higher large volumes (Va) (0.25 ± 0.18 versus 0.39 ± 0.09, p-value= 0.025) and higher volume to neck surface ratio (Ra) (1.32 ± 0.17 versus 1.54 ± 0.14, p-value= 0.021) in cases with occlusion failure.

CONCLUSIONS

Large aneurysm volumes (Va) and higher volume to neck surface ratio (Ra) could be associated with occlusion failure in aneurysms treated with the WEB device.

Long-term efficacy and safety of WovenEndoBridge (WEB)-assisted cerebral aneurysm embolization

PURPOSE

Long-term compaction, compression, migration, and recurrence rates of the WovenEndoBridge devices remain unknown. The purpose of this study was to detect these rates and safety profiles of the WovenEndoBridge within 7 years period.

MATERIALS AND METHODS

Eighty-three aneurysms of 79 patients treated with the WovenEndoBridge device were retrospectively evaluated using an occlusion scale (e.g. complete occlusion, neck remnant, and aneurysm remnant) on angiography images.

RESULTS

The residual aneurysm was observed in 11 (13%) aneurysms. The mean and median diameters of the recurrent aneurysms were 6 and 7 mm. Most of the recurrent aneurysms were complex type and/or ruptured. Mean diameters and the neck-to-body ratios of all residual aneurysms in the preoperative imaging exams were above 4 mm and 0.6, respectively. The median values of preoperative height and neck measurements were higher in the recurrent aneurysms than in the adequate occlusion group (p = 0.006, p = 0.019, respectively). There was a statistically significant positive relationship between preoperative height/neck measurements and the mean diameters of residual aneurysms (rs = 0.32 and p = 0.003; rs = 0.28 and p = 0.011, respectively). The WovenEndoBridge compaction/compression and migration were observed in 5 (45%) and 2 (18%) of the recurrent aneurysms. In 7 (64%) of the residual aneurysms, thrombosed areas were found within the aneurysm. In the follow-up period, four aneurysms (4.8%) were retreated due to widened residual aneurysm. Other aneurysms were improved or stable within 7 years.

DISCUSSION

Our adequate occlusion rate was 87%. Occlusion rates are less favorable than aneurysms with a long height, wide neck, or high neck-to-body ratio. Our study confirms the high safety and efficiency of the WovenEndoBridge. Compaction, compression, and/or migration of the WovenEndoBridge and the presence of intra-aneurysmal thrombosis are the main reasons for the recurrences.

Treatment of Wide-Necked Cerebral Aneurysms Using the WEB Device Including Flow Alteration Assessment With Color-Coded Imaging: A Single Center Experience

Objective

The Woven EndoBridge (WEB) device (MicroVention, Tustin, CA) has extended the treatment of cerebral aneurysms. Despite the fact that the WEB device has shown promising clinical results, little is known about the caused intra-aneurysmal flow alterations. Here we present our clinical experience with the WEB, including examining various syngo iFlow (Siemens AG, Erlangen, Germany) parameters to predict aneurysm occlusion.

Methods

We reviewed the data from patients with unruptured cerebral aneurysms treated with a WEB device between 2016 and 2020. Aneurysm occlusion and complications were assessed. Furthermore, different quantitative criteria were evaluated using syngo iFlow after digital subtraction angiography.

Results

A total of 26 patients hosting 26 cerebral aneurysms met the inclusion criteria. Follow-up was available for 21 patients, with a mean of 7.3 ± 6.3 months. A total of 71.4% (n = 15) of the aneurysms included were located in the anterior and 28.6% (n = 6) in the posterior circulation. Adequate aneurysm occlusion was achieved in 85.7% (n = 18). The iFlow parameters for reduced aneurysm outflow (ID-R) differed significantly from the parameters for reduced inflow (PI-R and PI-D) (P < 0.001). The parameters did not differ significantly between adequately and insufficiently occluded aneurysms. Only a trend towards a lower ID-R of insufficiently occluded aneurysms was observed (P = 0.063), indicating a potential predictive value for insufficient aneurysmal outflow. There was no treatment-related morbidity or mortality.

Conclusions

The applied syngo iFlow parameters confirmed that flow changes induced by the WEB device significantly affect outflow compared to inflow and have potential predictive value for adequate aneurysm occlusion.

Treatment of Proximal Posterior Inferior Cerebellar Artery Aneurysms by Intrasaccular Flow Disruption: A Multicenter Experience

BACKGROUND AND PURPOSE

Treatment of PICA aneurysms can be technically challenging by either surgical or endovascular means. Our aim was to report our preliminary experience with intrasaccular flow disruption using the Woven EndoBridge (WEB) for the treatment of proximal PICA aneurysms.

MATERIALS AND METHODS

Sixteen PICA aneurysms treated with the WEB at 3 institutions were retrospectively reviewed. Baseline patient and aneurysm characteristics, procedural specifics, clinical outcomes, and angiographic results were evaluated.

RESULTS

All aneurysms were located at the proximal, anteromedullary segment of the PICA. Seven aneurysms were ruptured. The median aneurysm size was 3.9 mm (range, 2-12 mm), and all aneurysms were wide-neck. WEB deployment failed in 1 case due to WEB protrusion in a small PICA aneurysm. Additional stent implantation was required for 2 aneurysms to improve intra-aneurysmal WEB positioning. One patient developed a partial posterior cerebral artery territory infarction with transient hemianopsia. Intraoperative rerupture of a ruptured aneurysm could be immediately stopped by WEB deployment due to intrasaccular stasis; however, it might have contributed to a slight disability of the patient. At last angiographic follow-up, 12/15 aneurysms (80%) were completely occluded and 3/15 (20%) had a neck remnant.

CONCLUSIONS

The preliminary results indicate that WEB treatment of proximal PICA aneurysms is feasible with a reasonable safety and efficacy profile. The advantages of intrasaccular flow disruption include preservation of the PICA, durable aneurysm occlusion, and omission of antiplatelet therapy. The low-profile WEB 17 delivery system might enable navigation to distal PICA aneurysms, which needs to be addressed further.

Aneurysm treatment with the Woven EndoBridge (WEB) device in the combined population of two prospective, multicenter series: 5-year follow-up

BACKGROUND

Evaluating a new endovascular treatment for intracranial aneurysms must not only demonstrate short-term safety and efficacy, but also evaluate longer-term outcomes (eg, delayed complications, anatomical results, retreatment). The current analysis reports the 5-year clinical and anatomical results of Woven EndoBridge (WEB) treatment in two European combined trial populations (WEBCAST (WEB Clinical Assessment of Intrasaccular Aneurysm Therapy) and WEBCAST-2).

METHODS

All adverse events occurring between the procedure and 5-year follow-up were independently evaluated by an expert. Aneurysm occlusion was evaluated by an independent core laboratory using a three-grade scale: complete occlusion, neck remnant, and aneurysm remnant. In cases where data were not available at 5-year follow-up, the last observation carry forward (LOCF) method was used.

RESULTS

The safety and efficacy populations comprised 100 patients and 95 aneurysms, respectively. No adverse event related to the device occurred after the procedure during the 5-year follow-up period. Mortality at 5 years was 7.0% (7/100 patients) including mortality related to the WEB (0/100, 0.0%), the procedure (1/100, 1.0%), and another condition (6/100, 6.0%). At 5 years, complete aneurysm occlusion was observed in 49/95 (51.6%) aneurysms, neck remnant in 25/95 (26.3%), and aneurysm remnant in 21/95 (22.1%). Retreatment rate at 5 years was 11.6% (11/95 aneurysms).

CONCLUSIONS

This analysis conducted in a population of patients with wide-neck bifurcation aneurysms confirms WEB's safety profile. Additional evidence demonstrates good stability of aneurysm occlusion with adequate occlusion (complete occlusion or neck remnant) at 5 years in 77.9% of aneurysms with a low retreatment rate (11.6%).

CLINICAL TRIAL REGISTRATION

WEBCAST and WEBCAST-2: Unique identifier: NCT01778322.

Comparison of angiographic outcomes and complication rates of WEB embolization and coiling for treatment of unruptured basilar tip aneurysms

Endovascular coiling represents the standard treatment for basilar tip aneurysms. Some of these aneurysms are not amenable to conventional coiling due to a complex aneurysm geometry, hence, novel devices such as the Woven Endobridge (WEB) have been developed. We retrospectively compared WEB embolization and coiling for the treatment of unruptured basilar tip aneurysms. Patients treated with WEB or coiling at four centers were reviewed. Procedure-related complications, clinical outcome and angiographic results were retrospectively evaluated and compared. Forty patients treated with the WEB and 35 patients treated by coiling were included. Stent-assistance was more often necessary for coiling than for WEB embolization (71% vs 2.5%, p < 0.001). The technical success rates were 100% for both methods. The overall complication rates were not significantly different between groups (WEB: 5%, coil: 11%, p = 0.409). Procedural morbidity rates were 9% in the coiling group and 2.5% in the WEB group (p = 0.334). There was no mortality. Treatment duration was shorter for WEB implantation than for coiling (p = 0.048). At mid-term follow-up, complete occlusion, neck remnants and aneurysm remnants were observed in 89%, 4% and 7% for the WEB, respectively, and in 100%, 0% and 0% for coiling. While complication rates and mid-term angiographic outcome was comparable between the groups, the WEB was associated with a shorter treatment duration and required stent-assistance less frequently. The choice of the treatment modality should be made based on the specific aneurysm characteristics, the individual experience of the neurointerventionalist and patient preference.

Woven EndoBridge in Wide-Neck Bifurcation Aneurysms: Digital Subtraction Angiography at 3-Year Follow-Up

Introduction: The Woven EndoBridge (WEB) device is a self-expanding intrasaccular braided-wire device for the treatment of wide-neck bifurcation aneurysms (WNBAs). Even though this device has an excellent safety profile and a low risk of rebleeding, little is known about its long-term effects. Material and Methods: All patients treated with WEB due to ruptured WNBAs were subjected to follow-up digital subtraction angiography (DSA) at 2 and 3 years after device deployment. The degree of residual neck was assessed through BOSS, Lubicz, and WEBCAST scales. Data on modified Rankin scale (mRS), bleeding events, and ischemic events occurring during this time period were collected as well. Lastly, overall and procedure-related mortality rates were calculated. Results: A total of 21 patients were treated between 1 January 2016, and 31 December 2018. DSA demonstrated a patency grade of 57.1% and 61.1% at 2 and 3 years, respectively. The overall 2-year mortality rate due to causes unrelated to the aneurysm was 14.3%. None of the patients were retreated between the 2- and the 3-year follow-up. No rebleeding or stroke events occurred during the follow-up. Conclusions: WEB-treated ruptured aneurysms showed an excellent degree of stability over time. The overall mortality rate—unrelated to the procedure–observed in our sample was higher than what reported in the literature, a possible bias associated with the COVID-19 pandemic.

Treatment of wide-necked bifurcation aneurysms with the eCLIPs device: 5-year experience of a single center

BACKGROUND

The endovascular clip system (eCLIPs) is a novel device with both neck bridging and flow-diversion properties that make it suitable for the treatment of wide-necked bifurcation aneurysms.

OBJECTIVE

To describe the clinical and radiologic outcomes of the eCLIPs device, including the first-in-man use of the latest version of the device.

METHODS

This is a retrospective case series on all the wide-necked bifurcation aneurysms treated with the eCLIPs device in our center. The immediate and latest radiologic and clinical outcomes were assessed.

RESULTS

The device was successfully implanted in 12 of 13 patients. After a median follow-up period of 19 months (range 3-64 months), all patients with available data (11/12) had a good radiologic outcome (modified Raymond-Roy classification scores of 1 or 2). Two patients (18.2%) underwent re-treatment with simple coiling through the device. One of these had a subarachnoid hemorrhage prior to re-treatment. There were no major complications (death or permanent neurologic deficits) associated with use of the device.

CONCLUSION

Our series demonstrates occlusion rates that are similar to those of standard stent-assisted coiling and intrasaccular flow diversion for wide-necked bifurcation aneurysms. Larger registry-based studies are necessary to support our findings.

Retreatment of Residual and Recurrent Aneurysms After Embolization With the Woven EndoBridge Device: Multicenter Case Series

BACKGROUND

The Woven EndoBridge (WEB) device (Terumno Corp. [parent company of Microvention]) was approved by the U.S. Food and Drug Administration as the first intrasaccular device for intracranial aneurysm treatment in December 2018. Its use has become more common since then, but both trial results and postmarket experiences have raised questions about the efficacy in achieving complete aneurysm obliteration. Retreatment after WEB embolization has not been extensively discussed.

OBJECTIVE

To discuss the incidence and retreatment of aneurysms after initial WEB embolization.

METHODS

Retrospective review across 13 institutions identified all occurrences of WEB retreatment within neurovascular databases. Details regarding demographics, aneurysm characteristics, treatment considerations, clinical outcomes, and aneurysm occlusion were obtained and analyzed.

RESULTS

Thirty aneurysms were retreated in 30 patients in a cohort of 342 WEB-treated aneurysms. The retreatment rate was 8.8%. Endovascular methods were used for 23 cases, and 7 were treated surgically. Two aneurysms presented with rehemorrhage after initial WEB embolization. Endovascular treatments included stent-assisted coiling (12), flow diversion (7), coiling (2), PulseRider (Johnson & Johnson)-assisted coiling (1), and additional WEB placement (1). Surgical treatments included primary clipping (6) and Hunterian ligation (1). There were no major complications within the study group.

CONCLUSION

WEB retreatments were successfully performed by a variety of techniques, including stent-assisted coiling, clipping, and flow diversion as the most common. These procedures were performed safely with subsequent obliteration of most aneurysms. The potential need for retreatment of aneurysms should be considered during primary WEB treatments.

Comparing treatment outcomes of various intracranial bifurcation aneurysms locations using the Woven EndoBridge (WEB) device

BACKGROUND

The Woven EndoBridge (WEB) device has Food and Drug Administration approval for treatment of wide-necked intracranial bifurcation aneurysms. The WEB device has been shown to result in adequate occlusion in bifurcation aneurysms overall, but its usefulness in the individual bifurcation locations has been evaluated separately only in few case series, which were limited by small sample sizes.

OBJECTIVE

To compare angiographic and clinical outcomes after treatment of bifurcation aneurysms at various locations, including anterior communicating artery (AComA), anterior cerebral artery (ACA) bifurcation distal to AComA, basilar tip, internal carotid artery (ICA) bifurcation, and middle cerebral artery (MCA) bifurcation aneurysms using the WEB device.

METHODS

A retrospective cohort analysis was conducted at 22 academic institutions worldwide to compare treatment outcomes of patients with intracranial bifurcation aneurysms using the WEB device. Data include patient and aneurysm characteristics, procedural details, angiographic and functional outcomes, and complications.

RESULTS

A total of 572 aneurysms were included. MCA (36%), AComA (35.7%), and basilar tip (18.9%) aneurysms were most common. The rate of adequate aneurysm occlusion was significantly higher for basilar tip (91.6%) and ICA bifurcation (96.7%) aneurysms and lower for ACA bifurcation (71.4%) and AComA (80.6%) aneurysms (p=0.04).

CONCLUSION

To our knowledge, this is the most extensive study to date that compares the treatment of different intracranial bifurcation aneurysms using the WEB device. Basilar tip and ICA bifurcation aneurysms showed significantly higher rates of aneurysm occlusion than other locations.

Determinants of cerebral aneurysm occlusion after embolization with the WEB device: a single-institution series of 215 cases with angiographic follow-up

Background

Woven EndoBridge (WEB) devices are becoming a reliable option for the treatment of wide-neck bifurcation aneurysms, but clear predictive factors are still missing to understand the one in five aneurysm remnant rate.

Objective

To evaluate occlusion outcomes after WEB treatment to identify potential determinants of aneurysm occlusion.

Methods

A single-center database with consecutive aneurysms treated with WEB between July 2012 and October 2021 was reviewed for potential determinants of aneurysm adequate occlusion (defined as a Bicêtre Occlusion Scale Score (BOSS) of 0, 0’, 1 or 2), through univariate and multivariable analysis. Patients without angiographic follow-up were excluded.

Results

215 of 247 individual aneurysms were included in the final analysis, of which 59 (27%) were ruptured. Mean age of patients was 56 years (range 23–90 years) and 65% were female. Mean angiographic follow-up was at 18 months (range 3–97 months). Adequate and complete occlusion were achieved in 171/215 (79.5%) and 135/215 (62.8%) of cases, respectively. Aneurysm irregular shape (aOR=0.42, 95% CI 0.20 to 0.88; p=0.02), aneurysm height (aOR=0.79, 95% CI 0.66 to 0.94; p<0.01), and WEB shape modification (aOR=0.98, 95% CI 0.97 to 1.00; p=0.02) were all independent predictors of aneurysm recurrence, whereas the WEB oversizing ratio (WEB width/aneurysm mean width) (aOR=16.4, 95% CI 1.4 to 266.7; p=0.04) was an independent predictor of adequate occlusion.

Conclusion

In this study we demonstrated that a width oversizing strategy of the WEB device was an independent predictor of aneurysm angiographic occlusion. Conversely, aneurysm height, irregular aneurysm, and WEB shape modification were all independent determinants of angiographic aneurysm remnant. These results may help to select aneurysms suitable for the WEB device and WEB sizing.

Microsurgical clipping vs Woven EndoBridge (WEB) device for the management of unruptured wide-neck bifurcation aneurysms

The Woven EndoBridge device (WEB) was introduced in 2010 to treat wide-neck bifurcation aneurysms (WNBAs). Three landmark studies have been conducted to assess its safety and efficacy: WEBCAST, WEBCAST 2, and French Observatory Study. However, these studies have not compared its safety and efficacy to other treatment modalities. In this study, we compare WEB versus microsurgical clipping in the management of unruptured WNBA. We conducted a retrospective study of unruptured WNBA meeting the morphological criteria to be amenable for WEB treatment operated on at our institution. Surgical morbidity, mortality, and occlusion rates were assessed. We compared our results to those reported in the cumulative population of the three WEB landmark studies at 1 year. A total of 84 patients with 89 WNBA were included. The most common aneurysm location was the middle cerebral artery bifurcation (n = 67/89, 75%). No operative mortality was observed. Morbidity comprised small-vessel vasospasm (n = 1/89, 1%) resulting in hemiparesis vs. 3% morbidity for WEB (p = .324). All but one (n = 1/89, 1%) WNBA were completely occluded vs WEB occlusion rate of 53% at 1 year, statistically significantly worse (p < .001). In our analysis, we were not able to show superiority of WEB in terms of procedural morbidity in comparison to microsurgical clipping, defined as worsening in mRS. Microsurgical clipping achieves statistically significantly higher rates of complete aneurysm occlusion, thus posing the question of whether the WEB should be presented as a viable, comparable alternative to patients amenable to surgical treatment.

Stent-assisted WEB embolization: aneurysm characteristics, outcome and case report of a WEB delivered through a stent

PURPOSE

Woven Endobridge (WEB) embolization has become a well-established endovascular treatment option for wide-necked bifurcation aneurysms. The objective was to analyse cases that required additional stent-implantation.

METHODS

Images of 178 aneurysms ≤ 11 mm treated by WEB only or by WEB plus stent were retrospectively reviewed, evaluating aneurysm characteristics, procedural specifics, adverse events and angiographic results. Moreover, we report a case of a WEB delivered through a previously implanted stent.

RESULTS

Additional stent implantation was performed in 15 patients (8.4%). Baseline patient and aneurysm characteristics were comparable between both groups. A single stent was used in 12 cases and 2 stents in Y-configuration in 3. Thromboembolic complications occurred more often with stent assistance (33.3% vs. 8.0%, p = 0.002), while ischemic stroke rates were comparable between both groups (0% vs. 1.8%, p = 1.0). Six-month angiographic follow-up showed complete occlusion, neck remnants and aneurysm remnants in 73.4%, 19.4% and 7.3% after WEB only, respectively, and in 66.7%, 20.0% and 16.7% after WEB plus stent, respectively (p = 0.538). A case report shows that WEB deployment through the struts of a previously implanted standard microstent is feasible, even if a VIA 33 microcatheter is needed.

CONCLUSION

In the present study, stent-assisted WEB embolization had a comparable safety and efficacy profile compared to treatment by WEB only. However, stent-assisted WEB embolization requires long-term anti-platelet medication, which annihilates the advantages of the WEB as a purely intrasaccular device.

CLINICAL TRIAL REGISTRATION NUMBER

N/A.

Middle Cerebral Artery Aneurysm Trial (MCAAT): A randomized care trial comparing surgical and endovascular management of MCA aneurysm patients

BACKGROUND

Whether the best management of middle cerebral artery (MCA) aneurysm patients is surgical or endovascular remains uncertain, with little evidence to guide decision-making. A randomized care trial offering MCA aneurysm patients a 50% chance of surgical and a 50% chance of endovascular management may optimize outcomes in the presence of uncertainty.

METHODS

The Middle Cerebral Artery Aneurysm Trial (MCAAT) is an investigator-initiated, multi-center, parallel group, prospective, 1:1 randomized controlled clinical trial. All adult patients with MCA aneurysms, ruptured or unruptured, amenable to surgical and endovascular treatment can be included. The composite primary outcome is 'Treatment Success': i) occlusion or exclusion of the aneurysm using the allocated treatment modality; ii) no intracranial hemorrhage during follow-up; iii) no retreatment of the target aneurysm during follow-up, iv) no residual aneurysm on angiographic follow-up and v) independence (mRS <3) at 1 year. The trial tests two versions of the same hypothesis (one for ruptured and one for unruptured MCA aneurysm patients): Surgical management will lead to a 15% absolute increase in the proportion of patients reaching Treatment Success from 55% to 70% (ruptured) or from 75% to 90% (unruptured aneurysm patients) compared to endovascular treatment (any method). In this pragmatic trial, outcome evaluations are by treating physicians, except for 1 year angiographic results which will be core lab assessed. The trial will be monitored by an independent data safety monitoring committee to assure safety of participants. MCAAT is registered at clinicaltrials.gov: NCT05161377.

CONCLUSION

Patients with MCA aneurysms can be optimally managed within a care trial protocol.

Treatment of octogenarians and nonagenarians with aneurysmal subarachnoid hemorrhage: a 17-year institutional analysis

BACKGROUND

Outcomes for octogenarians and nonagenarians after an aneurysmal subarachnoid hemorrhage (aSAH) are particularly ominous, with mortality rates well above 50%. The present analysis examines the neurologic outcomes of patients ≥ 80 years of age treated for aSAH.

METHOD

A retrospective review was performed of all aSAH patients treated at Barrow Neurological Institute from January 1, 2003, to July 31, 2019. Patients were placed in 2 groups by age, < 80 vs ≥ 80 years. The ≥ 80-year-old group of octogenarians and nonagenarians was subsequently analyzed to compare treatment modalities. Poor neurologic outcome was defined as a modified Rankin Scale (mRS) score of > 2.

RESULTS

During the study period, 1418 patients were treated for aSAH. The mean (standard deviation) age was 55.1 (13.6) years, the mean follow-up was 24.6 (40.0) months, and the rate of functional independence (mRS 0-2) at follow-up was 54% (751/1395). Logistic regression analysis found increasing age strongly associated with declining functional independence (R² = 0.929, p < 0.001). Forty-three patients ≥ 80 years old were significantly more likely to be managed endovascularly than with open microsurgery (67% [n = 29] vs 33% [n = 14], p < 0.001). Compared with younger patients, those ≥ 80 years old had an increased risk of mortality and poor neurologic outcomes at follow-up. In the ≥ 80-year-old group, only 4 patients had good outcomes; none of the 4 had preexisting comorbidities, and all 4 were treated endovascularly.

CONCLUSIONS

Age is a significant prognostic indicator of functional outcomes and mortality after aSAH. Most octogenarians and nonagenarians with aSAH will become severely disabled or die.

Ten Years of Clinical Evaluation of the Woven EndoBridge: A Safe and Effective Treatment for Wide-Neck Bifurcation Aneurysms

Intrasaccular flow disruption is an innovative approach for the endovascular treatment of intracranial aneurysms. As of now, only one device is currently available worldwide: the Woven EndoBridge (WEB) device (MicroVention, Aliso Viejo, CA, USA). After 10 years of clinical use and careful clinical evaluation of the WEB device by multiple prospective, multicenter studies, this article is summarizing the current knowledge regarding this endovascular technique; indications, modalities, safety and efficacy of the WEB procedure are described.

Adjustment of Malpositioned Woven EndoBridge Device Using Gooseneck Snare: Complication Management Technique

The Woven EndoBridge (WEB) is an intrasaccular flow-disrupting device for the treatment of wide-necked saccular cerebral aneurysms. As with any neuroendovascular device, complications in the form of malpositioning and migration must be managed quickly and safely. Few studies have reported complication management techniques in instances of dislocated or migrated WEB devices. We retrospectively describe a case of a malpositioned WEB device that was successfully adjusted with the use of a gooseneck snare. Multiple other intra-procedural bailout strategies for management of WEB malposition and migration were considered, and are herein discussed. Operators should be aware of the causes of WEB malposition and a variety of bailout strategies.

Intracranial aneurysm treatment with intrasaccular flow disruption: comparison of WEB-21 and WEB-17 systems

BACKGROUND

New generations of Woven EndoBridge (WEB) devices (WEB-21 and WEB-17) are available to treat aneurysms with a width <6.5 mm. Limited comparisons between both systems exist in the literature, but mid-term efficacy has not been compared. Our study aimed to compare the indications, feasibility, and safety of both systems and to evaluate their efficacy at mid-term follow-up (12 months).

METHODS

Aneurysms treated with WEB-21 and WEB-17 were extracted from a prospective database. Patient and aneurysm characteristics, complications, and anatomical results were analyzed by an interventional neuroradiologist, independent of the procedures.

RESULTS

From June 2015 to November 2019, 87 patients with 92 aneurysms were treated with WEB-21 (38/92, 41.3%) and WEB-17 (54/92, 58.7%). WEB-21 and WEB-17 had high treatment feasibility (97.4% and 94.4%, respectively). A higher percentage of ruptured aneurysms were treated with WEB-17 (9.3%) than with WEB-21 (2.6%; p=0.03). Morbidity and mortality at 1 month were similar in both groups (no morbidity in either group, and mortality 2.7% in the WEB-21 group and 2.0% in the WEB-17 group). The rate of complete and adequate aneurysm occlusion was not significantly higher with the WEB-17 system (59.2% and 95.9%, respectively) compared with the WEB-21 (52.9% and 85.3%, respectively).

CONCLUSIONS

This study showed the high feasibility of aneurysm treatment with both the WEB-21 and WEB-17 systems. Indications were relatively similar with both devices except for ruptured aneurysms, which were more frequently treated with the WEB-17 device. Efficacy at 12 months (complete and adequate occlusions) was slightly, but not significantly, better with the WEB-17 device.

The ARTISSE intrasaccular device for intracranial aneurysm treatment: short-term, mid-term and long-term clinical and angiographic results

BACKGROUND

The concept of intra-aneurysmal flow disruption has emerged as a new paradigm for the treatment of primarily bifurcation aneurysms. The purpose of this study was to determine the clinical and angiographic outcomes of patients treated with the new ARTISSE intrasaccular device (ISD).

METHODS

Selected patients with bifurcation aneurysms that matched the indications of the ARTISSE ISD defined by the manufacturer were treated in a single center. Clinical and angiographic follow-up was conducted at 6 and 36 months. Aneurysm occlusion was assessed using the Raymond-Roy classification scale.

RESULTS

Nine subjects with nine unruptured bifurcation aneurysms were enrolled. Mean aneurysm size was 7.2±1.2 mm (range 5.5-9.7 mm). An adequate aneurysm occlusion (defined as a complete occlusion or a neck remnant) was achieved in 6/9 patients (66.7%) at 6 months and 4/7 patients (57.1%) at 36 months follow-up. Two of the nine subjects experienced a major stroke (22.2%), including one on postoperative day 1 due to a procedure-related parent vessel occlusion and subsequent ischemic stroke. The other major stroke occurred within the 36-month follow-up period during treatment of a separate aneurysm with coils, leading to perforation with hemorrhagic stroke causing a permanent neurological deficit.

CONCLUSION

The ARTISSE ISD was successfully deployed in all nine cases. There were, however, several procedure-related complications and results in terms of angiographic aneurysm occlusion were modest.

Influence of operator experience on the technical and clinical results of Woven EndoBridge endovascular treatment for intracranial aneurysms

BACKGROUND & PURPOSE

The safety and efficacy of the Woven EndoBridge (WEB) device has been proven in recent multicenter trials. This study investigated whether operator experience influences WEB treatment-related outcomes.

MATERIAL AND METHODS

This was a retrospective analysis of a prospectively collected multicenter database. The data of all patients who underwent WEB treatment for an intracranial aneurysm from March 2014 to June 2020 in two high-volume centers were pooled. Operator experience was indexed by the number of WEB treatments performed previously. The primary endpoint was the overall complication rate. Secondary endpoints were long-term adequate (Raymond-Roy classification of 1-2.) angiographic occlusion, WEB-related complications, number of WEB not deployed, procedure duration, and radiation exposure (air kerma).

RESULTS

Among 237 patients (mean age 59.4 +/- 11.5 years) treated with WEB (median aneurysm diameter, 5.8 mm; interquartile range 4.5-7 mm), WEB-related complications occurred in 28 patients (11.8%) and adequate long-term occlusion was achieved for 154 aneurysms (86%). The median number of WEB treatment performed previously per operator was 20 (IQR, 9-41). The overall complication rate, WEB-related complication rate and aneurysm occlusion rate were not significantly correlated with WEB operator experience. There were also no significant correlations between the WEB operator experience and the number of WEB not deployed, procedure duration or radiation exposure.

CONCLUSION

There was no significant association between the number of WEB treatments previously performed per operator and any technical or clinical results after intracranial aneurysm treatment with WEB. These results imply a relatively short learning curve for this device in high-volume neurovascular centers.

"Shelf" Technique Using a Novel Braided Self-Expandable Stent for the Treatment of Wide-Necked Bifurcation Aneurysms

Background

Different endovascular techniques exist for treatment of cerebral wide-necked bifurcation aneurysms (WNBA). We present the “shelf” technique with the novel woven LVIS EVO stent, which enables forming a buttress at the level of the aneurysm neck to prevent coil prolapse and additional stenting.

Methods

Single-center retrospective analysis of patients treated with the “shelf” technique by using LVIS EVO stent in incidental WNBAs between January 2020 and March 2021. Inclusion criteria were saccular aneurysms with neck width ≥4 mm or a dome/neck ratio ≤2. Primary endpoint was a favorable navigation to the target vessel and successful deployment of the LVIS EVO stent with forming a buttress that enables aneurysm occlusion by subsequent coiling. Secondary endpoints were aneurysm occlusion on follow-up, procedure-related complications and clinical outcome.

Results

A total of 15 patients were included. The primary end point was reached in 100% of cases. A complete aneurysm occlusion at the end of the procedure was achieved in 14/15 patients (93%). No intraprocedural complications occurred. All patients except one were discharged with an modified Rankin Scale (mRS) of 0. Procedure-related morbidity was 7%. Median follow-up imaging was 115 days (7–419 days) and available for 11/15 (73%) of the patients. Of those, 10 (91%) individuals had a complete aneurysm occlusion and 1 showed a residual neck. In all patients, the covered branch was patent and no ischemic complications occurred during follow-up.

Conclusion

This study demonstrates the “shelf” technique with LVIS EVO stents as a feasible and safe treatment option for WNBAs with very good short-term occlusion rates.

Optimal Woven EndoBridge (WEB) Device Size Selection Using Automated Volumetric Software

INTRODUCTION

Selecting the appropriate Woven EndoBridge (WEB) device sizing for the treatment of wide-neck bifurcation aneurysms (WNBAs) remains challenging. The aim of this study was to evaluate different volumetric-based imaging methodologies to predict an accurate WEB device size selection to result in a successful implantation.

METHODS

All consecutive patients treated with WEB devices for intracranial aneurysms from January 2019 to June 2020 were included. Aneurysm dimensions to calculate aneurysm volumes were measured using three different modalities: automated three-dimensional (3D) digital subtraction angiography (DSA), manual 3D DSA, and two-dimensional (2D) DSA. The device-aneurysm volume (DAV) ratio was defined as device volume divided by the aneurysm volume. WEB volumes and the DAV ratios were used for assessing the device implantation success and follow-up angiographic outcomes at six months. Pearson correlation, Wilcoxon Rank Sum test, and density approximations were used for estimating the WEB volumes and the imaging modality volumes for successful implantation.

RESULTS

A total of 41 patients with 43 aneurysms were included in the study. WEB device and aneurysm volume correlation coefficient was highest for 3D automatic (r = 0.943), followed by 3D manual (r = 0.919), and 2D DSA (r = 0.882) measurements. Measured median volumes were significantly different for 3D automatic and 2D DSA (p = 0.017). The highest rate of successful implantation (87.5%) was between 0.6 and 0.8 DAV ratio.

CONCLUSION

Pre-procedural assessment of DAV ratios may increase WEB device implantation success. Our results suggest that volumetric measurements, especially using automated 3D volumes of the aneurysms, can assist in accurate WEB device size selection.

Impact of A1 Asymmetry on the Woven EndoBridge Device in Anterior Communicating Artery Aneurysms

BACKGROUND AND PURPOSE

Woven EndoBridge (WEB) devices are increasingly used to treat intracranial aneurysms. A1 asymmetry contributes to anterior communicating artery aneurysm formation and to treatment instability after coiling. We sought to evaluate whether A1 asymmetry had an impact on angiographic outcome in anterior communicating artery aneurysms treated with the WEB.

MATERIALS AND METHODS

Anterior communicating artery aneurysms treated between July 2012 and July 2020 with the WEB from an institutional review board-approved database were reviewed. A1 asymmetry was categorized as the following: absence of the A1 segment on 1 side (unilateral A1) versus bilateral A1. Univariate and multivariable analyses assessed independent predictors of adequate (WEB Occlusion Scale A, B, and C) and complete occlusion (WEB Occlusion Scale A and B).

RESULTS

Forty-eight individual aneurysms (47 patients) were included in the final analysis, of which 16 (33%) were acutely ruptured. The mean size was 6.5 (SD, 2.2) mm. Adequate and complete occlusion was achieved in 33 (69%) and 30 (63%) cases, respectively. Unilateral A1 was associated with significantly higher rates of adequate (92% versus 60% for bilateral A1; P = .03) and complete occlusion (92% versus 50% for bilateral A1; P < .01). Multivariable logistic regression confirmed unilateral A1 as an independent predictor of both adequate (OR = 10.6; 95% CI, 1.6-220.7; P = .04) and complete occlusion (OR = 9.5, 95% CI, 1.5-190.2; P = .04. A sensitivity analysis comparing unilateral "functional" A1 with bilateral "functional" A1 showed similar results. WEB shape modification was not influenced by the unilateral A1 configuration (P = .70).

CONCLUSIONS

Anterior communicating artery aneurysms with a unilateral A1 configuration treated with WEB devices are associated with better angiographic outcome than those with bilateral A1. This finding supports the hypothesis that WEB devices are resistant to unilateral flow in the aneurysm as opposed to coils.

Nautilus-Assisted Coiling of an Unruptured Wide-Necked Aneurysm of the Posterior Communicating Artery

A variety of recently introduced devices have allowed more complex aneurysms to be rendered for endovascular embolization. Tiny and sophisticated implants are nowadays designed to provide further either temporary or permanent remodeling of the wide-necked aneurysms and improve coil occlusion rates.^1-4 Such improvements in the technical armamentarium include the Woven EndoBridge (Sequent Medical, California, USA), the Medina Embolic Device (Medtronic, Irvine, California, USA), The Contour Neurovascular System (Cerus Endovascular, Fremont, California, USA), and pCONUS 2 HPC (Phenox, GmbH, Bohum, Germany).^5-7 Intrasaccular neck bridging is a conceptually new technique descending from the theoretical combination of intrasaccular flow diversion and temporary-stent assisted coiling.⁸ The Nautilus (EndoStream Medical, Tel Aviv, Israel) is an intrasaccular bridging device that offers complete neck reconstruction in coil embolization of wide-neck cerebral aneurysms. It has been granted a CE mark by the European Union. The detachable intrasaccular implant comprises flexible and "tornado-like"-shaped Nitinol-based layers. The device is compatible with a standard microcatheter with minimal 0.0165″ inner diameter and is fully radiopaque and fully resheathable. The device's intrasaccular nature and the fact that it does not harbor any intraluminal satellite parts suggest that the implant can be safely used in both unruptured and ruptured case scenarios without the need for dual antiplatelet therapy. This is what we consider a great advantage of the proposed technique over the alternative options of intrasaccular and intraluminal flow diversion. This technical video (Video 1) demonstrates the successful obliteration of a complex posterior communicating artery aneurysm with Nautilus-assisted endovascular coiling. To our knowledge, this is the first technical video demonstrating an in-vivo and step-by-step implementation of this novel device.

WEB device for treatment of posterior communicating artery aneurysms

BACKGROUND

Woven EndoBridge (WEB) device treatment of wide-neck bifurcation aneurysms has proved to be safe and effective, but the use of these devices in sidewall aneurysms has been reported only in a small number of case series.

OBJECTIVE

To report our results in a cohort of consecutive patients in whom a WEB device was used as first-line treatment for posterior communicating artery (PComA) aneurysms.

METHODS

We conducted a retrospective analysis of a prospectively maintained database of PComA aneurysms treated with a WEB device in our institution from June 1, 2012 to November 15, 2020. Clinical and radiological findings were evaluated at immediate and last follow-up.

RESULTS

A total of 219 aneurysms were treated with a WEB device, including 15 PComA aneurysms in 15 patients, 10 of which were ruptured. Aneurysms were wide necked, with a mean aspect ratio of 1.6 (range 0.7-3.0) and a mean neck size of 4.2 mm (range 2.6-7.4 mm). No intraoperative rupture occurred and only one thromboembolic event was noted. Among the group with at least a 3-month digital subtraction angiography (DSA) follow-up, complete and adequate occlusion were obtained in 54% and 72%, respectively (average follow-up 13 months). Re-treatment was needed for two initially ruptured aneurysms. No procedure-related morbidity or mortality was reported.

CONCLUSION

This series suggests the high safety profile of WEB devices even when used in off-label indications. Treatment with these devices seems to be a valuable strategy for ruptured wide-neck PComA aneurysms, avoiding the need for antiplatelet medication. However, occlusion rates should be investigated in further larger studies.

Woven Endobridge Embolization Versus Microsurgical Clipping for Unruptured Anterior Circulation Aneurysms: A Propensity Score Analysis

BACKGROUND

Intrasaccular flow-disruption represents a new paradigm in endovascular treatment of wide-necked bifurcation aneurysms.

OBJECTIVE

To retrospectively compare Woven Endobridge (WEB) embolization with microsurgical clipping for unruptured anterior circulation aneurysms using propensity score adjustment.

METHODS

A total of 63 patients treated with WEB and 103 patients treated with clipping were compared based on the intention-to-treat principle. The primary outcome measures were immediate technical treatment success, major adverse events, and 6-mo complete aneurysm occlusion.

RESULTS

The technical success rates were 83% for WEB and 100% for clipping. Procedure-related complications occurred more often in the clipping group (13%) than the WEB group (6%, adjusted P < .01). However, the rates of major adverse events were comparable in both groups (WEB: 3%, clip: 4%, adjusted P = .53). At the 6-mo follow-up, favorable functional outcomes were achieved in 98% of the WEB embolization group and 99% of the clipping group (adjusted P = .19). Six-month complete aneurysm occlusion was obtained in 75% of the WEB group and 94% of the clipping group (adjusted P < .01).

CONCLUSION

Microsurgical clipping was associated with higher technical success and complete occlusion rates, whereas WEB had a lower complication rate. Favorable functional outcomes were achieved in ≥98% of both groups. The decision to use a specific treatment modality should be made on an individual basis and in accordance with the patient's preferences.

Intrasaccular Flow Disruption with the Woven EndoBridge for Narrow-Necked Aneurysms: A Safety and Feasibility Study

OBJECTIVE

The Woven EndoBridge (WEB) received U.S. Food and Drug Administration approval for endovascular treatment of wide-necked bifurcation aneurysms. We evaluated the feasibility, safety, and efficacy of the WEB for treatment of narrow-necked aneurysms.

METHODS

This multicenter study included 17 narrow-necked aneurysms, defined by a neck width <4 mm and a dome-to-neck ratio >2. Aneurysm characteristics, treatment strategies, technical success, complications, and angiographic outcomes were retrospectively assessed.

RESULTS

Aneurysm locations included the internal carotid artery (7 cases), anterior communicating artery (4 cases), middle cerebral artery (4 cases), and basilar artery (2 cases). The median aneurysm size was 7.4 mm with a median neck width of 2.3 mm. The technical success rate was 100%. There were no neurological complications. Angiographic control revealed complete and adequate occlusion in 13 of 15 (86.7%) and 14 of 15 (93.3%) cases, respectively, after 6 months and in 6 of 7 (85.6%) and 7 of 7 (100%) cases, respectively, after a median of 13 months. Two aneurysms were retreated with flow diverters.

CONCLUSIONS

WEB embolization of narrow-necked aneurysms was technically feasible and safe and might be considered as an alternative treatment option to conventional coiling in selected cases.

Intracranial aneurysm treatment with WEB and adjunctive stent: preliminary evaluation in a single-center series

Background

Intrasaccular flow disruption with WEB is a safe and efficacious technique that has significantly changed endovascular management of wide-neck bifurcation aneurysms (WNBAs). Use of stent in combination with WEB is occasionally required. We analyzed the frequency of use, indications, safety, and efficacy of the WEB–stent combination.

Methods

All aneurysms treated with WEB and stent were extracted from a prospectively maintained database. Patient and aneurysm characteristics, complications, and anatomical results were independently analyzed by a physician independent of the procedures.

Results

From June 2011 to January 2020, 152 patients with 157 aneurysms were treated with WEB. Of these, 17/152 patients (11.2%) with 19/157 aneurysms (12.1%) were treated with WEB device and stent. Indications were very wide neck with a branch emerging from the neck in 1/19 (5.2%) aneurysms and WEB protrusion in 18/19 (94.7%). At 1 month, no morbimortality was reported. At 6 months, anatomical results were complete aneurysm occlusion in 15/17 aneurysms (88.2%), neck remnant in 1/17 (5.9%), and aneurysm remnant in 1/17 (5.9%). At 12 months, there was complete aneurysm occlusion in 13/14 aneurysms (92.9%) and neck remnant in 1/14 (7.1%).

Conclusions

Combining WEB and stent is a therapeutic strategy to manage WNBA. In our series, this combination was used in 11.2% of patients treated with WEB, resulting in no morbidity or mortality with a high efficacy at 6 and 12 months (complete aneurysm occlusion in 88.2% and 92.9%, respectively).