Aneurysm Study of Pipeline in an Observational Registry (ASPIRe)

Acutely Ruptured Intracranial Aneurysms Treated with Flow-Diverter Stents: A Systematic Review and Meta-Analysis

BACKGROUND

The implantation of flow-diverter stents for the treatment of ruptured intracranial aneurysms required further investigation.

PURPOSE

Our aim was to analyze the outcomes after flow diversion of ruptured intracranial aneurysms.

DATA SOURCES

A systematic search of 3 databases was performed for studies published from 2006 to 2018.

STUDY SELECTION

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies (from 2010 to 2018) reporting acutely ruptured intracranial aneurysms treated with flow diversion.

DATA ANALYSIS

Random-effects meta-analysis was used to pool the following: aneurysm occlusion rate, complications, rebleeding, and factors influencing the studied outcomes.

DATA SYNTHESIS

We included 20 studies evaluating 223 patients with acutely ruptured intracranial aneurysms treated with flow-diverter stents. Immediate angiographic occlusion was obtained in 32% (29/86; 95% CI, 15.4%-48%; I² = 79.6%) of aneurysms, whereas long-term complete/near-complete aneurysm occlusion was 88.9% (162/189; 95% CI, 84%-93.5%; I² = 20.9%) (mean radiologic follow-up of 9.6 months). The treatment-related complication rate was 17.8% (42/223; 95% CI, 11%-24%; I² = 52.6%). Complications were higher in the posterior circulation (16/72 = 27%; 95% CI, 14%-40%; I² = 66% versus 18/149 = 11.7%; 95% CI, 7%-16%; I² = 0%) (P = .004) and after treatment with multiple stents (14/52 = 26%; 95% CI, 14%-45%; I² = 59%) compared with a single stent (20/141 = 10%; 95% CI, 5%-15%; I² = 0%) (P = .004). Aneurysm rebleeding after treatment was 4% (5/223; 95% CI, 1.8%-7%; I² = 0%) and was higher in the first 72 hours.

LIMITATIONS

Small and retrospective series.

CONCLUSIONS

Flow-diversion treatment of ruptured intracranial aneurysms yields a high rate of long-term angiographic occlusion with a relatively low rate of aneurysm rebleeding. However, treatment is associated with a complication rate of 18%. When coiling or microsurgical clipping are not feasible strategies, anterior circulation ruptured aneurysms can be effectively treated with a flow-diversion technique, minimizing the number of stents deployed. Given the 27% rate of complications, flow diversion for ruptured posterior circulation aneurysms should be considered only in selected cases not amenable to other treatments.

Safety and efficacy of the Derivo Embolization Device for the treatment of unruptured intracranial aneurysms: a multicentric study

Background

The Derivo Embolization Device (DED) is a novel flow diverter stent that provides increased x-ray visibility, an improved delivery system, and potentially reduced thrombogenicity. The objective of this study was to evaluate the early safety and efficacy of the second-generation DED.

Methods

We retrospectively analyzed all patients with unruptured intracranial aneurysms (UIAs) treated with the DED between November 2015 and December 2017 in three German tertiary care centers. Procedural details, complications, and morbidity within 30 days after treatment, as well as the aneurysm occlusion rates after 6 months (O’Kelly–Marotta scale, OKM), were evaluated.

Results

Implantation of the DED was attempted in 42 patients with 42 aneurysms. All procedures were technically successful. Multiple DEDs were used in three aneurysms (7.2%) and adjunctive coiling in 11 (26.2%). Procedure-related complications occurred in four cases (9.5%) including three thromboembolic events and one aneurysm perforation. The morbidity rate was 2.4% and there was no mortality. One patient suffered an ischemic stroke with persistent aphasia at 30-day follow-up due to a thromboembolic infarct (modified Rankin Scale score 1). Among 33 patients (78.6%) available for angiographic follow-up, complete (OKM D) and favorable (OKM C+D) aneurysm occlusion was obtained in 72.7% (24/33) and 87.9% (29/33), respectively.

Conclusions

Endovascular treatment of UIAs with the DED is associated with high procedural safety and adequate occlusion rates. Examinations at 1- and 2-year follow-up will provide data on the long-term safety and angiographic outcomes of this device.

Virtual stenting of intracranial aneurysms: A pilot study for the prediction of treatment success based on hemodynamic simulations

Endovascular treatment of intracranial aneurysms using flow-diverting devices has revolutionized the treatment of large and complex lesions due to its minimally invasive nature and potential clinical outcomes. However, incomplete or delayed occlusion and persistent intracranial aneurysm growth are still an issue for up to one-third of the patients. We evaluated two patients with intracranial aneurysm located at the internal carotid artery who were treated with flow-diverting devices and had opposite outcomes. Both patients presented with similar aneurysms and were treated with the same device, but after a 1-year follow-up, one case presented with complete occlusion (Case 1) and the other required further treatment (Case 2). To reproduce the interventions, virtual stents were deployed and blood flow simulations were carried out using the respective patient-specific geometries. Afterward, hemodynamic metrics such as aneurysmal inflow reduction, wall shear stresses, oscillatory shear, and inflow concentration indices were quantified. The hemodynamic simulations reveal that for both cases, the neck inflow was clearly reduced due to the therapy (Case 1: 19%, Case 2: 35%). In addition, relevant hemodynamic parameters such as time-averaged wall shear stress (Case 1: 35.6%, Case 2: 57%) and oscillatory shear (Case 1: 33.1%, Case 2: 26.7%) were decreased considerably. However, although stronger relative reductions occurred in the unsuccessful case, the absolute flow values in the successful case were approximately halved. The findings demonstrate that a high relative effect of endovascular devices is not necessarily associated with the desired treatment outcome. Instead, it appears that a successful intracranial aneurysm therapy requires a certain patient-specific inflow threshold.

Update on flow diverters for the endovascular management of cerebral aneurysms

Flow diversion has become a well-accepted option for the treatment of cerebral aneurysms. Given the significant treatment effect of flow diverters, numerous options have emerged since the initial Pipeline embolization device studies. In this review, the authors describe the available flow diverters, both endoluminal and intrasaccular, addressing nuances of device design and function and presenting data on complications and outcomes, where available. They also discuss possible future directions of flow diversion.

Patterns, Predictors, and Outcomes of Postprocedure Delayed Hemorrhage Following Flow Diversion for Intracranial Aneurysm Treatment

OBJECTIVE

To evaluate patterns, predictors, and outcomes of postprocedure delayed hemorrhage (PPDH) following flow diversion therapy for intracranial aneurysm treatment.

METHODS

From 2012 to 2016, 50 patients with 52 aneurysms were treated with the Pipeline embolization device. Device placement was performed as a standalone therapy or with adjunctive coil embolization. Patients underwent dual antiplatelet therapy for 6 months after treatment. Medical comorbidities; aneurysm traits; and treatment factors, including platelet function testing, were studied. Statistical analysis was performed using cross-tabulation.

RESULTS

Six PPDHs (12%) occurred 2-16 days (mean 6.8 days) after Pipeline placement, manifesting as 1 of 2 distinct patterns: convexity subarachnoid hemorrhage (cSAH) (n = 4) or lobar intraparenchymal hemorrhage (IPH) (n = 2). All PPDHs occurred ipsilateral to the device; 1 IPH occurred ipsilateral but in a different arterial territory. PPDH occurred in both treated anterior communicating artery aneurysms. Cases of PPDH demonstrated on average lower P2Y12 reaction unit values at the time of treatment. Platelet function testing at the time of hemorrhage was consistently hypertherapeutic. Patients with cSAH had only minimal worsening of modified Rankin Scale score at the time of discharge, whereas the 2 patients with IPH experienced significant deterioration.

CONCLUSIONS

PPDH is a poorly understood complication following flow diversion therapy that can result in significant morbidity. In our experience, nonaneurysmal cSAH does not result in poor clinical outcomes, whereas IPH leads to long-term deficits or death. As previously suggested, there appears to be a correlation between low P2Y12 reaction unit values and PPDH.

Parent Artery Reconstruction for Large or Giant Cerebral Aneurysms Using the Tubridge Flow Diverter: A Multicenter, Randomized, Controlled Clinical Trial (PARAT)

BACKGROUND AND PURPOSE

Although flow diverters have been reported with favorable clinical and angiographic outcomes in various literatures, randomized trials determining their true effectiveness and safety are still in lack. The Parent Artery Reconstruction for Large or Giant Cerebral Aneurysms Using the Tubridge Flow Diverter (PARAT) trial was designed to evaluate the safety and efficacy of the Tubridge flow diverter in the treatment of large or giant aneurysms in comparison with Enterprise stent-assisted coiling.

MATERIALS AND METHODS

This prospective, multicenter, randomized trial was conducted at 12 hospitals throughout China. Enrolled adults with unruptured large/giant intracranial aneurysms were randomly assigned (1:1) to receive either Enterprise stent-assisted coiling or Tubridge flow diverter implantation. The primary end point was complete occlusion at 6-month follow-up, while secondary end points included technical success, mortality, target vessel-related stroke, aneurysm bleeding, in-stent stenosis, parent artery occlusion, and the frequency of all adverse events.

RESULTS

Among 185 enrolled subjects, 41 withdrew before procedure initiation. Overall, 82 subjects underwent Tubridge implantation, and 62 subjects were primarily treated with stent-assisted coiling. The results of 6-month follow-up imaging included complete occlusion rates of 75.34% versus 24.53% for the Tubridge and stent-assisted coiling groups, respectively, with a calculated common odds ratio of 9.4 (95% confidence interval, 4.14-21.38; P < .001). There was a higher, nonsignificant frequency of complications for Tubridge subjects. Multivariate analysis showed a decreased stroke rate at the primary investigational site, with a marginal P value (P = .051).

CONCLUSIONS

This trial showed an obviously higher rate of large and giant aneurysm obliteration with the Tubridge FD over Enterprise stent-assisted coiling. However, this higher obliteration rate came at the cost of a nonsignificantly higher rate of complications. Investigational site comparisons suggested that a learning curve for flow-diverter implantation should be recognized and factored into trial designs.

European Multicenter Study for the Evaluation of a Dual-Layer Flow-Diverting Stent for Treatment of Wide-Neck Intracranial Aneurysms: The European Flow-Redirection Intraluminal Device Study

BACKGROUND AND PURPOSE

Endoluminal reconstruction with flow-diverting stents represents a widely accepted technique for the treatment of complex intracranial aneurysms. This European registry study analyzed the initial experience of 15 neurovascular centers with the Flow-Redirection Intraluminal Device (FRED) system.

MATERIALS AND METHODS

Consecutive patients with intracranial aneurysms treated with the FRED between February 2012 and March 2015 were retrospectively reviewed. Complications and adverse events, transient and permanent morbidity, mortality, and occlusion rates were evaluated.

RESULTS

During the defined study period, 579 aneurysms in 531 patients (median age, 54 years; range, 13-86 years) were treated with the FRED. Seven percent of patients were treated in the acute phase (≤3 days) of aneurysm rupture. The median aneurysm size was 7.6 mm (range, 1-36.6 mm), and the median neck size 4.5 mm (range, 1-30 mm). Angiographic follow-up of >3 months was available for 516 (89.1%) aneurysms. There was progressive occlusion witnessed with time, with complete occlusion in 18 (20%) aneurysms followed for up to 90 ± 14 days, 141 (82.5%) for 180 ± 20 days, 116 (91.3%) for 1 year ± 24 days, and 122 (95.3%) aneurysms followed for >1 year. Transient and permanent morbidity occurred in 3.2% and 0.8% of procedures, respectively. The overall mortality rate was 1.5%.

CONCLUSIONS

This retrospective study in real-world patients demonstrated the safety and efficacy of the FRED for the treatment of intracranial aneurysms. In most cases, treatment with a single FRED resulted in complete angiographic occlusion at 1 year.

Transvenous Aneurysm Sac and Rupture Point Coil Embolization of Direct Carotid Cavernous Fistula after Pipeline Embolization

A delayed aneurysm rupture after flow diverter therapy is a rare but serious complication. Due to the anatomical specificity, a delayed rupture of a carotid cavernous aneurysm may cause a direct carotid cavernous fistula (dCCF). We present a novel therapeutic approach for treatment of dCCF after flow diverter therapy using the Pipeline embolization device (PED). An 86-year-old woman suffered from dCCF after PED embolization. A microcatheter was advanced through the transvenous approach into the cavernous sinus (CS) and further inserted into the aneurysm sac via the rupture point. Coil embolization of both the aneurysm sac and a small part of the CS adjacent to the fistulous site could achieve not only the immediate aneurysm occlusion but also the rupture point obliteration with a small amount of coil mass in the CS.

Clinical and angiographic outcomes in patients with intracranial aneurysms treated with the pipeline embolization device: intra-procedural technical difficulties, major morbidity, and neurological mortality decrease significantly with increased operator experience in device deployment and patient management

PURPOSE

Flow diversion constitutes a pivotal advancement in endovascular intracranial aneurysm treatment, but requires development of a new skill set. The aim of this study is to determine whether outcomes after treatment with the Pipeline Embolization Device improve with experience.

METHODS

We retrospectively reviewed all patients with intracranial aneurysms treated with Pipeline at two centers over a 4.5-year period. Baseline patient and aneurysm characteristics, complications, and angiographic outcomes were analyzed.

RESULTS

One hundred forty patients underwent 150 Pipeline procedures to treat 167 intracranial aneurysms during the study period, 109 women, mean age 55.4 years. One hundred twenty-six aneurysms were ICA, mean size 10.2 mm and mean neck 6.4 mm. Intra-procedural technical difficulties were higher during the first 75 procedures compared with the subsequent 75 (13.3 vs 2.7%; p = 0.03), as combined major morbidity and neurological mortality (14.7 vs 4%; p = 0.046). In multivariate regression analysis, increased operator experience with Pipeline remained an independent predictor of intra-procedural technical difficulties (p = 0.02, odds ratio (OR) 0.015, 95% CI 0.0004-0.55) and combined major morbidity and neurological mortality (p = 0.03, OR 0.16, 95% CI 0.03-0.84). At last follow-up, 123 aneurysms were completely occluded (81.5%, mean 24 months). In our cohort, age ≤ 53 years was an independent predictor of complete aneurysm occlusion at last follow-up (p = 0.001, OR 0.92, 95% CI 0.88-0.97). Five aneurysms were retreated (3.3%).

CONCLUSION

The Pipeline embolization device is an effective treatment for intracranial aneurysms. The risk of intra-procedural technical difficulties and combined major morbidity and neurological mortality decreases significantly with increased operator experience in Pipeline deployment and patient management.

Treatment of Middle Cerebral Artery Aneurysms with Flow-Diverter Stents: A Systematic Review and Meta-Analysis

BACKGROUND

The safety and efficacy of flow-diversion treatment of MCA aneurysms have not been well-established.

PURPOSE

Our aim was to evaluate angiographic and clinical outcomes after flow diversions for MCA aneurysms.

DATA SOURCES

A systematic search of PubMed, MEDLINE, and Embase was performed for studies published from 2008 to May 2017.

STUDY SELECTION

According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we selected studies with >5 patients describing angiographic and clinical outcomes after flow-diversion treatment of MCA aneurysms.

DATA ANALYSIS

Random-effects meta-analysis was used to pool the following outcomes: aneurysm occlusion rate, procedure-related complications, rupture rate of treated aneurysms, and occlusion of the jailed branches.

DATA SYNTHESIS

Twelve studies evaluating 244 MCA aneurysms were included in this meta-analysis. Complete/near-complete occlusion was obtained in 78.7% (95% CI, 67.8%-89.7%) of aneurysms. The rupture rate of treated aneurysms during follow-up was 0.4% per aneurysm-year. The rate of treatment-related complications was 20.7% (95% CI, 14%-27.5%), and approximately 10% of complications were permanent. The mortality rate was close to 2%. Nearly 10% (95% CI, 4.7%-15.5%) of jailed arteries were occluded during follow-up, whereas 26% (95% CI, 14.4%-37.6%) had slow flow. Rates of symptoms related to occlusion and slow flow were close to 5%.

LIMITATIONS

Small and retrospective series could affect the strength of the reported results.

CONCLUSIONS

Given the not negligible rate of treatment-related complications, flow diversion for MCA aneurysms should be considered an alternative treatment when traditional treatment methods are not feasible. However, when performed in this select treatment group, high rates of aneurysm occlusion and protection against re-rupture can be achieved.

Expanding the use of flow diverters beyond their initial indication: treatment of small unruptured aneurysms

Background

Experience with the endovascular treatment of unruptured small intracranial aneurysms by flow diverter devices is still limited.

Objective

To assess the safety and efficacy of the SILK flow diverter (SFD) in the treatment of small unruptured cerebral aneurysms (<10 mm).

Methods

We performed a retrospective review of a prospectively maintained database of patients treated with a SFD between July 2008 and December 2013 at 4 institutions in Spain to identify all patients with small unruptured aneurysms (<10 mm). Data for patient demographics, aneurysm characteristics, and technical procedures were analyzed. Angiographic and clinical findings were recorded during the procedure and at 6- and 12-month follow-ups.

Results

A total of 109 small aneurysms were treated with a SFD in 104 patients (78 women; 26 men; mean, median, and range of age: 55.2, 57.1, and 19–80 years, respectively). A total of 60 patients were asymptomatic (57.7%). All except 7 aneurysms (6.4%) arose from the anterior circulation. The mean size of the aneurysms was 4.7±1.9 mm. At 6 months, the neuromorbidity and neuromortality rates were 2.9% and 0.9%, respectively. Imaging at the 12-month follow-up showed complete occlusion, neck remnants, and residual aneurysm in 88.5% (69/78), 7.7% (6/78), and 3.3% (3/78) of cases, respectively. No delayed hemorrhage occurred.

Conclusions

The findings suggest that the indications for SFD can be safely extended to small intracranial aneurysms.

Lack of Association between Statin Use and Angiographic and Clinical Outcomes after Pipeline Embolization for Intracranial Aneurysms

BACKGROUND AND PURPOSE

Use of statin medications has been demonstrated to improve clinical and angiographic outcomes in patients receiving endovascular stent placement for coronary, peripheral, carotid, and intracranial stenoses. We studied the impact of statin use on long-term angiographic and clinical outcomes after flow-diverter treatment of intracranial aneurysms.

MATERIALS AND METHODS

We performed a post hoc analysis from pooled patient-level datasets from 3 Pipeline Embolization Device studies: the International Retrospective Study of the Pipeline Embolization Device, the Pipeline for Uncoilable or Failed Aneurysms Study, and the Aneurysm Study of Pipeline in an Observational Registry. We analyzed data comparing 2 subgroups: 1) patients on statin medication, and 2) patients not on statin medication at the time of the procedure and follow-up. Angiographic and clinical outcomes were compared by using the χ² test, Fisher exact test, or Wilcoxon rank sum test.

RESULTS

We studied 1092 patients with 1221 aneurysms. At baseline, 226 patients were on statin medications and 866 patients were not on statin medications. The mean length of clinical and angiographic follow-up was 22.1 ± 15.1 months and 28.3 ± 23.7 months, respectively. There were no differences observed in angiographic outcomes at any time point between groups. Rates of complete occlusion were 82.8% (24/29) versus 86.4% (70/81) at 1-year (P = .759) and 93.3% (14/15) versus 95.7% (45/47) at 5-year (P = 1.000) follow-up for statin-versus-nonstatin-use groups, respectively. There were no differences in any complication rates between groups, including major morbidity and neurologic mortality (7.5% versus 7.1%, P = .77).

CONCLUSIONS

Our study found no association between statin use and angiographic or clinical outcomes among patients treated with the Pipeline Embolization Device.

Treatment of Large and Giant Middle Cerebral Artery Aneurysms: Risk Factors for Unfavorable Outcomes

OBJECTIVE

This study aimed to assess the clinical and radiologic outcomes after neurosurgical treatment of large and giant aneurysms of the middle cerebral artery (MCA). In addition, we aimed to identify risk factors for unfavorable outcomes.

METHODS

This retrospective study included 105 patients with 106 large or giant MCA aneurysms treated with neurosurgical methods, including microsurgery and endovascular treatment, over a 15-year period.

RESULTS

The mean aneurysm size was 15.3 ± 7.1 mm. Ten (9.4%) were giant aneurysms. The MCA bifurcation was the most common aneurysm site, followed by the MCA trunk and distal MCA. Aneurysm clipping was the most common treatment method, followed by clipping or trapping with bypass surgery and endovascular treatment. However, acute cerebral infarction was the most common complication (16.0%), poor outcomes (modified Rankin Scale score, 3-6) developed in 12.3% of aneurysms after treatment, and 6.6% of treated aneurysms needed retreatment. Multivariate analysis showed that independent risk factors for acute cerebral infarction after treatment were aneurysms located on the MCA trunk and 2 or more underlying diseases. Initial presentation with subarachnoid hemorrhage and complications during treatment were independent risk factors for poor outcomes. In addition, endosaccular coiling was an independent risk factor for retreatment.

CONCLUSIONS

Neurosurgical management should be considered a priority for large and giant MCA aneurysms because of the high rupture rate and clinical symptoms. However, treatment outcomes remain unsatisfactory. Therefore, tailored management with consideration of risk factors for unfavorable outcomes should be implemented.

Periprocedural outcomes and early safety with the use of the Pipeline Flex Embolization Device with Shield Technology for unruptured intracranial aneurysms: preliminary results from a prospective clinical study

BACKGROUND AND PURPOSE

The Pipeline Embolization Device (PED) has become a routine first-line option for treatment of intracranial aneurysms (IAs). We assessed the early safety and technical success of a new version of PED, Pipeline Flex Embolization Device with Shield Technology (Pipeline Shield), which has the same design and configuration but has been modified to include a surface synthetic biocompatible polymer.

MATERIALS AND METHODS

The Pipeline Flex Embolization Device with Shield Technology (PFLEX) study is a prospective, single-arm, multicenter study for the treatment of unruptured IAs using Pipeline Shield. The primary study endpoints included the occurrence of major stroke in the territory supplied by the treated artery or neurologic death at 1 year post-procedure. Secondary endpoints included the rate of Pipeline Shield-related or procedure-related serious or non-serious adverse events. Analyses were conducted to evaluate early safety findings in the 30-day post-procedure period as well as technical procedural success outcomes.

RESULTS

Fifty patients with 50 unruptured target IAs were enrolled. Mean aneurysm diameter was 8.82±6.15 mm. Thirty-eight aneurysms (76%) were small (<10 mm). Device deployment was technically successful with 98% of devices. Complete wall apposition was achieved immediately post-procedure in 48 cases (96%). No major strokes or neurologic deaths were reported in the 30-day post-procedure period.

CONCLUSIONS

The results of this first experience with the new Pipeline Flex corroborate the early safety of the device. Mid-term and long-term follow-up examinations will provide data on safety outcomes at the 6-month and 1-year follow-up periods.

CLINICAL TRIAL REGISTRATION

NCT02390037.

Incidence of delivery wire recapture failure with the Pipeline Flex device

Background

The Pipeline Flex embolization device has several advantages over the first-generation Pipeline embolization device (Covidien, Dublin, Republic of Ireland). Despite these advantages, we have observed frequent difficulty in recapturing the device's delivery wire.

Objective

To prospectively document the incidence of failure to recapture the delivery wire.

Methods

We tracked our experience in patients undergoing endovascular treatment with a flow-diverting stent for cerebral aneurysms between 1 May and 30 September 2016. Patient and lesion characteristics, device dimensions, and technical outcomes of delivery wire recapture were prospectively recorded for each device.

Results

Eighteen devices were deployed in 15 patients by the senior author (FCA) during this period. Failure to recapture the delivery wire occurred in 10 of 18 (56%) cases. No adverse outcomes of delivery wire recapture failure were encountered in this series.

Conclusions

The incidence of delivery wire recapture failure with the Pipeline Flex device is high. Failure to recapture the delivery wire carries a theoretical risk of stent displacement when re-navigating across the device, and endovascular surgeons should be aware of this limitation. Authors are encouraged to report delivery wire recapture failure rates in future clinical series in which the Pipeline Flex device is used.

Evaluation of Pipeline Flex delivery system for the treatment of unruptured aneurysms

INTRODUCTION

Refinements in endovascular technology have revolutionized the treatment of intracranial aneurysms (IAs) with the development of flow-diversion technology. The first generation of the Pipelin Embolization Device (PED) has demonstrated its safety and efficacy. However, the deployment technique was a difficult task that often led to complex maneuvers. The Pipeline Flex Embolization Device (PED Flex) is the second generation and its introduction has arrived with high expectations due to a completely redesigned delivery system that intends to overcome deployment difficulties seen in the previous generation. Areas covered: Preclinical studies, mechanism of action of flow-diverters, technical aspects and deployment system of the PED Flex, and clinical outcomes with both PED generations. Expert commentary: Flow diversion has allowed us to treat lesions that would be otherwise challenging for surgical clipping or unsuitable for other endosaccular strategies. Although the experience with PED Flex is limited, initial results suggest its safety and short-term efficacy.