Extending the Indications of Flow Diversion to Small, Unruptured, Saccular Aneurysms of the Anterior Circulation

Neuroform atlas stent treatment for 533 intracranial aneurysms in a large Chinese cohort: complication risk factor analysis

BACKGROUND

The newest generation of Neuroform Atlas stent™ (Stryker, Fremont, California) represents a recent advance of cerebral laser-cut microstents for the treatment of intracranial wide-necked aneurysms, and postoperative complications have been observed among Western patients. We assessed predictors of complications, morbidity, and unfavourable outcomes in a large cohort of patients with aneurysms that were treated with Neuroform Atlas stents in China.

METHODS

This retrospective study included subjects who were treated with Atlas stents in China from November 2020 to January 2022.

RESULTS

A total of 522 consecutive patients (mean age, 58.9 ± 9.9 years; female, 65.3% [341/522]) with 533 aneurysms were included in the study. In the early postoperative period, the neurological morbidity rate was 7.3% (38/522), the ischaemic stroke rate was 5.0% (26/522), the aneurysm rupture subarachnoid haemorrhage rate was 2.3% (12/522), and the mRS score deterioration rate was 5.4% (28/522). The mortality rate was 0.8% (4/522) in the postoperative period. The rate of neurological morbidity during the follow-up period was 1.2% (6/486). In the multifactor prediction analysis, cerebral infarction, Hunt-Hess grade (3-5), procedure duration, stent length and coil protrusion into the parent artery were found to be independent predictors of neurologic morbidity. The procedure duration, stent length and coil protrusion into the parent artery were found to be independent predictors of mRS score deterioration.

CONCLUSIONS

The incidence of SCA (stent-assisted coiling)-related complications with the Atlas stent in this study population was comparable to that in Western populations. We identified the procedure duration and stent length as novel independent predictors of SCA-related ischaemic stroke, neurological morbidity, and mRS score deterioration among the Chinese population.

Predictors of aneurysm occlusion after treatment with flow diverters: a systematic literature review

BACKGROUND

Flow diverters (FDs) have become an integral part of treatment for brain aneurysms.

AIM

To summarize available evidence of factors associated with aneurysm occlusion (AO) after treatment with a FD.

METHODS

References were identified using the Nested Knowledge AutoLit semi-automated review platform between January 1, 2008 and August 26, 2022. The review focuses on preprocedural and postprocedural factors associated with AO identified in logistic regression analysis. Studies were included if they met the inclusion criteria of study details (ie, study design, sample size, location, (pre)treatment aneurysm details). Evidence levels were classified by variability and significancy across studies (eg, low variability ≥5 studies and significance in ≥60% throughout reports).

RESULTS

Overall, 2.03% (95% CI 1.22 to 2.82; 24/1184) of screened studies met the inclusion criteria for predictors of AO based on logistic regression analysis. Predictors of AO with low variability in multivariable logistic regression analysis included aneurysm characteristics (aneurysm diameter), particularly complexity (absence of branch involvement) and younger patient age. Predictors of moderate evidence for AO included aneurysm characteristics (neck width), patient characteristics (absence of hypertension), procedural (adjunctive coiling) and post-deployment variables (longer follow-up; direct postprocedural satisfactory occlusion). Variables with a high variability in predicting AO following FD treatment were gender, FD as re-treatment strategy, and aneurysm morphology (eg, fusiform or blister).

CONCLUSION

Evidence of predictors for AO after FD treatment is sparse. Current literature suggests that absence of branch involvement, younger age, and aneurysm diameter have the highest impact on AO following FD treatment. Large studies investigating high-quality data with well-defined inclusion criteria are needed for greater insight into FD effectiveness.

Comparison of pipeline embolization device and tubridge flow diverter for posterior circulation aneurysms: A multicentre propensity score matched study

Rationale and objectives

The off-label use of flow diverters (FDs) has broadened to include treating aneurysms in posterior circulation (PC). A novel flow diverter, the Tubridge flow diverter (TFD), has been created in China specifically for treating PC aneurysms. However, studies comparing between pipeline embolization device (PED) and TFD are rare. Thus, our study aimed to explore the effectiveness of PED and TFD in the treatment of PC aneurysms using a propensity score matched cohort design.

Methods

Retrospective data collection was conducted on patients who underwent treatment with either PED or TFD over the period from 2015 through 2020. Propensity score matching (PSM) was employed to calibrate for patient age; history of ischemic stroke; aneurysm size; morphology; location and neck; number of FDs; parent vessel diameter; and the employment of assisted coiling and balloon techniques. Data on previously ruptured aneurysms was not included in the analysis. A comparison was conducted between the two devices to assess perioperative complications, aneurysm occlusion rates, and functional outcomes.

Results

A total of 252 PC aneurysms were treated in 248 patients. Clinical and imaging follow-ups were lost in 26 and 47 patients, respectively. Major perioperative complications occurred in 7.5% of the cases, with favorable clinical outcomes in 91.0% and complete occlusion in 79.1%. Eighty-two (32.5%) aneurysms were treated with TFD, while 170 (67.5%) aneurysms were treated with PED. PSM was used to account for these significant variations, producing 82 matched pairs of unruptured aneurysms treated with PED or TFD. In terms of functional and angiographic outcomes, no significant differences were found between PED and TFD (functional outcome, p = 0.594 and angiographic outcome, p = 0.415). However, more perioperative major complications were found in patients treated with TFD (p = 0.005) compared with those receiving PED.

Conclusion

The comparative study of PED and TFD in the treatment of PC aneurysms resulted in positive clinical results and sustained occlusion rates, with acceptable perioperative complications. However, higher quality studies are needed to enhance our understanding of the use of FDs for treating of PC aneurysms.

Systematic Review and Meta-Analysis of Endovascular Therapy Effectiveness for Unruptured Saccular Intracranial Aneurysms

Background

Currently, endovascular treatment of intracranial aneurysms (ICAs) is limited by low complete occlusion rates. The advent of novel endovascular technology has expanded the applicability of endovascular therapy; however, the superiority of novel embolic devices over the traditional Guglielmi detachable coils (GDCs) is still debated. We performed a systematic review of literature that reported Raymond-Roy occlusion classification (RROC) rates of modern endovascular devices to determine their immediate and follow-up occlusion effectiveness for the treatment of unruptured saccular ICAs.

Methods

A search was conducted using electronic databases (PUBMED, Cochrane, ClinicalTrials.gov, Web of Science). We retrieved studies published between 2000-2022 reporting immediate and follow-up RROC rates of subjects treated with different endovascular ICA therapies. We extracted demographic information of the treated patients and their reported angiographic RROC rates.

Results

A total of 80 studies from 15 countries were included for data extraction. RROC rates determined from angiogram were obtained for 21,331 patients (72.5% females, pooled mean age: 58.2 (95% CI: 56.8-59.6), harboring 22,791 aneurysms. The most frequent aneurysm locations were the internal carotid artery (46.4%, 95% CI: 41.9%-50.9%), the anterior communicating artery (26.4%, 95% CI: 22.5%-30.8%), the middle cerebral artery (24.5%, 95% CI:19.2%-30.8%) and the basilar tip (14.4%, 95% CI:11.3%-18.3%). The complete occlusion probability (RROC-I) was analyzed for GDCs, the Woven EndoBridge (WEB), and flow diverters. The RROC-I rate was the highest in balloon-assisted coiling (73.9%, 95% CI: 65.0%-81.2%) and the lowest in the WEB (27.8%, 95% CI:13.2%-49.2%). The follow-up RROC-I probability was homogenous in all analyzed devices.

Conclusions

We observed that the coil-based endovascular therapy provides acceptable rates of complete occlusion, and these rates are improved in balloon-assisted coils. Out of the analyzed devices, the WEB exhibited the shortest time to achieve >90% probability of follow-up complete occlusion (~18 months). Overall, the GDCs remain the gold standard for endovascular treatment of unruptured saccular aneurysms.

The Impact of Dual Antiplatelet Therapy Duration on Unruptured Aneurysm Occlusion After Flow Diversion: A Multicenter Study

OBJECTIVE

Endoluminal flow diversion reduces blood flow into intracranial aneurysms, promoting thrombosis. Postprocedural dual antiplatelet therapy (DAPT) is necessary for the prevention of thromboembolic complications. The purpose of this study is to therefore assess the impact that the type and duration of DAPT has on aneurysm occlusion rates and iatrogenic complications after flow diversion.

METHODS

A retrospective review of a multicenter aneurysm database was performed from 2012 to 2020 to identify unruptured intracranial aneurysms treated with single device flow diversion and ≥12-month follow-up. Clinical and radiologic data were analyzed with aneurysm occlusion as a function of DAPT duration serving as a primary outcome measure.

RESULTS

Two hundred five patients underwent flow diversion with a single pipeline embolization device with 12.7% of treated aneurysms remaining nonoccluded during the study period. There were no significant differences in aneurysm morphology or type of DAPT used between occluded and nonoccluded groups. Nonoccluded aneurysms received a longer mean duration of DAPT (9.4 vs 7.1 months, P = 0.016) with a significant effect of DAPT duration on the observed aneurysm occlusion rate (F(2, 202) = 4.2, P = 0.016). There was no significant difference in the rate of complications, including delayed ischemic strokes, observed between patients receiving short (≤6 months) and prolonged duration (>6 months) DAPT (7.9% vs 9.3%, P = 0.76).

CONCLUSIONS

After flow diversion, an abbreviated duration of DAPT lasting 6 months may be most appropriate before transitioning to low-dose aspirin monotherapy to promote timely aneurysm occlusion while minimizing thromboembolic complications.

Comaneci stent-angioplasty for the optimization of inadequately deployed flow diverter stents

BACKGROUND AND PURPOSE

In endovascular procedures, inadequate deployment of a flow diverter stent is a highly concerning technical complication that can lead to acute parent vessel occlusion and ischaemic events. This study aimed to assess the off-label use of the Comaneci device in managing technical difficulties associated with flow diversion.

MATERIALS AND METHODS

We conducted an analysis of all flow diverter procedures documented in our prospectively collected database. Our objective was to identify patients with inadequately deployed implants who underwent Comaneci stent-angioplasty. Both Comaneci 17 and Comaneci 21 devices were utilized to address and remediate technical complications related to stent deployment. We reviewed anatomical features, technical details, intraprocedural complications, as well as clinical and angiographic outcomes.

RESULTS

Thirty-one Comaneci devices were employed to remediate 31 inadequately deployed flow diverter stents. Successful resolution of technical complications associated with flow diverter placement was achieved in all attempted cases. No clinically significant complications were attributed to the technique, and no mortality was observed during the study.

CONCLUSION

Technical issues arising from flow diverter stent deployment are formidable complications. Familiarity with appropriate corrective manoeuvres is essential to achieve successful outcomes. The Comaneci device can be safely and effectively incorporated into the range of techniques used to rectify inadequately deployed stents.

Safety and efficacy of endovascular treatment for tiny ruptured intracranial aneurysms with low-profile visualized intraluminal support stents

BACKGROUND

Endovascular treatment for tiny ruptured intracranial aneurysms is known to be technically challenging. Thus, we aimed to investigate the safety and efficacy of low-profile visualized intraluminal support (LVIS) stents in the treatment of tiny ruptured intracranial aneurysms.

METHODS

From April 2014 to June 2019, among 90 patients with tiny ruptured aneurysms who were treated at our institution endovascularly, 28 underwent stent-assisted coiling with LVIS stents. The clinical and angiographic results were reviewed.

RESULTS

In the LVIS group, complete occlusion was achieved in 27 patients (96.4%). Intraprocedural thrombus formation occurred in 3 patients (10.7%). Follow-up angiography in 24 patients at 6-12 months showed complete occlusion in 23 patients (95.8%) and no aneurysm recurrence. In the coiling-only group, complete occlusion was achieved in 58 patients (93.5%). Intraprocedural aneurysm rupture occurred in 2 patients (3.2%), and postprocedural ischemia occurred in 4 patients (6.5%), with a complication rate of 9.7%. Follow-up angiography in 52 patients at 6-12 months showed complete occlusion in 43 patients (82.7%) and aneurysm recurrence in 7 patients (9.2%). No significant (p > 0.05) differences existed between the two groups.

CONCLUSIONS

The LVIS stent is safe and effective in the treatment of tiny ruptured intracranial aneurysms.

Prospective study on embolization of intracranial aneurysms with the pipeline device (PREMIER study): 3-year results with the application of a flow diverter specific occlusion classification

BACKGROUND

The pipeline embolization device (PED; Medtronic) has presented as a safe and efficacious treatment for small- and medium-sized intracranial aneurysms. Independently adjudicated long-term results of the device in treating these lesions are still indeterminate. We present 3-year results, with additional application of a flow diverter specific occlusion scale.

METHODS

PREMIER (prospective study on embolization of intracranial aneurysms with pipeline embolization device) is a prospective, single-arm trial. Inclusion criteria were patients with unruptured wide-necked intracranial aneurysms ≤12 mm. Primary effectiveness (complete aneurysm occlusion) and safety (major neurologic event) endpoints were independently monitored and adjudicated.

RESULTS

As per the protocol, of 141 patients treated with a PED, 25 (17.7%) required angiographic follow-up after the first year due to incomplete aneurysm occlusion. According to the Core Radiology Laboratory review, three (12%) of these patients progressed to complete occlusion, with an overall rate of complete aneurysm occlusion at 3 years of 83.3% (115/138). Further angiographic evaluation using the modified Cekirge-Saatci classification demonstrated that complete occlusion, neck residual, or aneurysm size reduction occurred in 97.1%. The overall combined safety endpoint at 3 years was 2.8% (4/141), with only one non-debilitating major event occurring after the first year. There was one case of aneurysm recurrence but no cases of delayed rupture in this series.

CONCLUSIONS

The PED device presents as a safe and effective modality in treating small- and medium-sized intracranial aneurysms. The application of a flow diverter specific occlusion classification attested the long-term durability with higher rate of successful aneurysm occlusion and no documented aneurysm rupture.

TRIAL REGISTRATION

NCT02186561.

Effects of stent-assisted coiling in comparison with flow diversion on intracranial aneurysms

Objective

The aim of this study was to investigate the efficacy and complications of stent-assisted coiling in comparison with flow diversion for wide-necked intracranial aneurysms.

Methods

Patients with wide-necked intracranial aneurysms who were treated with stent-assisted coiling or flow diversion were respectively, enrolled into the stent-assisted coiling or flow diversion treatment group. The clinical and angiographic data were analyzed.

Results

A total of 61 patients with intracranial aneurysms underwent stent-assisted coiling, including 35 (57.4%) female and 26 (42.6%) male patients with 21 (34.4%) ruptured and 40 (65.6%) unruptured aneurysms. Also, 53 patients underwent deployment of flow-diverting devices, including 30 (56.6%) female and 23 (43.4%) male patients with 25 (47.2%) ruptured and 28 (52.8%) unruptured aneurysms. Stent-assisted coiling was performed successfully in 60 patients with 63 stents deployed, and immediate aneurysm occlusion was complete occlusion in 38 (62.3%) aneurysms, residual neck in 12 (19.7%), and residual aneurysm in 10 (16.4%). Procedure-related complications included in-stent thrombosis in three (4.9%) patients, coil protrusion in three (4.9%), and re-rupture of one (1.6%) aneurysm, with a total complication rate of 11.5%. In the flow diversion group, a pipeline embolization device alone was deployed in each of the 24 (45.3%) patients, adjunctive coiling combined with a pipeline device in 29 (54.7%), and double pipeline devices in each of the 6 (11.3%) patients. Immediately after treatment, complete occlusion was achieved in 3 (5.7%) patients with adjunctive coiling, residual neck in 3 (5.7%), and residual aneurysm in 47 (88.7%). Procedure-related complications included aneurysm rebleeding in one patient (1.9%). Clinical and angiographic follow-up was performed 13–49 months (median 29) after the procedure for 49 (80.3%) patients with stent-assisted coiling, with complete aneurysm occlusion in 27 (55.1%) aneurysms, residual neck in 3 (6.1%), residual aneurysm in 5 (10.2%), and recurrence in 14 (28.6%). Follow-up was performed for 14–37 (median 25) months in 45 (84.9%) patients with flow diversion treatment, with complete occlusion in 39 (86.7%) patients, residual neck in 5 (11.1%), residual aneurysm in 1 (2.2%), and no aneurysm recurrence.

Conclusions

Stent-assisted coiling comes with more complications but fewer permanent aneurysm occlusions than flow diverters, and flow diverters are superior to stent-assisted coiling in the treatment of wide-necked intracranial aneurysms, especially in the long-term effect.

The Safety and Efficacy of Flow Diversion versus Conventional Endovascular Treatment for Intracranial Aneurysms: A Meta-analysis of Real-world Cohort Studies from the Past 10 Years

BACKGROUND

Although the flow diverter has advantages in the treatment of intracranial aneurysms, pooled studies that directly compare it with conventional endovascular treatments are rare.

PURPOSE

Our aim was to compare the safety and efficacy of flow-diverter and conventional endovascular treatments in intracranial aneurysms.

DATA SOURCES

We performed a comprehensive search of the literature using PubMed, EMBASE, and the Cochrane Database.

STUDY SELECTION

We included only studies that directly compared the angiographic and clinical outcomes of flow-diverter and conventional endovascular treatments.

DATA ANALYSIS

Random effects or fixed effects meta-analysis was used to pool the cumulative rate of short- and long-term angiographic and clinical outcomes.

DATA SYNTHESIS

Eighteen studies with 1001 patients with flow diverters and 1133 patients with conventional endovascular treatments were included; 1015 and 1201 aneurysm procedures were performed, respectively. The flow-diverter group had aneurysms of a larger size (standard mean difference, 0.22; 95% CI, 0.03-0.41; P = .026). There was a higher risk of complications in the flow-diverter group compared with the conventional endovascular group (OR, 1.4; 95% CI, 1.01-1.96; P = .045) during procedures. The follow-up angiographic results of flow-diverter treatment indicated a higher rate of complete occlusion (OR, 2.55; 95% CI, 1.70-3.83; P < .001) and lower rates of recurrence (OR, 0.24; 95% CI, 0.12-0.46; P < .001) and retreatment (OR, 0.31; 95% CI, 0.21-0.47; P < .001).

LIMITATIONS

Limitations include a retrospective, observational design in some studies, high heterogeneity, and selection bias.

CONCLUSIONS

Compared with the conventional endovascular treatments, the placement of a flow diverter may lead to more procedure-related complications, but there is no difference in safety, and it is more effective in the long term.

Recovery from Cranial Nerve Symptoms after Flow Diversion without Coiling for Unruptured Very Large and Giant ICA Aneurysms

BACKGROUND AND PURPOSE

Cranial nerve symptoms, including visual impairment and ophthalmoplegia, are one of the most common presentations of very large and giant (≥15 mm) ICA aneurysms. In this study, we evaluated the treatment outcomes of flow diversion and conventional coiling in terms of recovery from cranial nerve symptoms and postoperative complications.

MATERIALS AND METHODS

Seventy-nine patients with unruptured ICA aneurysms of >15 mm who were treated with flow diversion or conventional coiling between December 2009 and December 2020 were retrospectively evaluated. We compared the radiologic and clinical outcomes, including recovery from cranial nerve symptoms, between the 2 groups.

RESULTS

Twenty-eight of 49 patients (57.1%) treated with flow diversion and 10 of 30 patients (33.3%) treated with conventional coiling initially presented with cranial nerve symptoms (P = .068). In the clinical follow-up, the symptom recovery rate was significantly higher in those treated with flow diversion (15 [50%] versus 3 [25%] with conventional coiling, P = .046). Multivariate logistic regression analysis demonstrated that flow diversion was significantly associated with symptom recovery (OR, 7.425; 95% CI, 1.091-50.546; P = .040). The overall postoperative complication rate was similar (flow diversion, 10 [20.4%]; conventional coiling, 6 [20.0%], P = .965), though fatal hemorrhagic complications occurred only in patients with intradurally located aneurysms treated with flow diversion (4 [8.2%] versus 0 [0.0%] with coiling, P = .108).

CONCLUSIONS

Flow diversion without coiling for very large and giant ICA aneurysms yielded a higher rate of recovery from cranial nerve symptoms, but it may be related to an increased hemorrhagic complication rate, especially for intradurally located aneurysms.

Hemodynamic analysis for endovascular treatment in small unruptured intracranial aneurysms: a matched comparison study of flow diverter versus LVIS

BACKGROUND

We compared the treatment of small unruptured intracranial aneurysms (UIAs) with flow diverter and LVIS-assisted coiling to determine the effects of hemodynamic changes caused by different stent and coil packing in endovascular treatment.

METHODS

Fifty-one UIAs in 51 patients treated with pipeline embolization device (PED) were included in this study and defined as the PED group. We matched controls 1:1 and enrolled 51 UIAs who were treated with LVIS stent, which were defined as the LVIS group. Computational fluid dynamics were performed to assess hemodynamic alterations between PED and LVIS. Clinical analysis was also performed between these two groups after the match.

RESULTS

There was no difference in procedural complications between the two groups (P = 0.558). At the first angiographic follow-up, the complete occlusion rate was significantly higher in the LVIS group compared with that in the PED group (98.0% vs. 82.4%, P = 0.027). However, during the further angiographic follow-up, the complete occlusion rate in the PED group achieved 100%, which was higher than that in the LVIS group (98.0%). Compared with the LVIS group after treatment, cases in the PED group showed a higher value of velocity in the aneurysm (0.03 ± 0.09 vs. 0.01 ± 0.01, P = 0.037) and WSS on the aneurysm (2.32 ± 5.40 vs. 0.33 ± 0.47, P = 0.011). Consequently, the reduction ratios of these two parameters also showed statistical differences. These parameters in the LVIS group showed much higher reduction ratios. However, the reduction ratio of the velocity on the neck plane was comparable between two groups.

CONCLUSIONS

Both LVIS and PED were safe and effective for the treatment of small UIAs. However, LVIS-assisted coiling produced greater hemodynamic alterations in the aneurysm sac compared with PED. The hemodynamics in the aneurysm neck may be a key factor for aneurysm outcome.

Implantation of Large Diameter (5.5-6 mm) Derivo Embolization Devices for the Treatment of Cerebral Aneurysms

BACKGROUND

The efficacy of flow diverters is dependent upon robust wall apposition in the parent artery. Usage in large caliber cerebral vessels has therefore been limited as few implants with diameters > 5 mm exist. We present our initial experience in treating cerebral aneurysms using the 5.5 mm and 6 mm diameter implants of the Derivo embolization device (DED).

METHODS

Our prospectively maintained institutional database was reviewed to identify patients in whom a > 5 mm DED was implanted between November 2016 and February 2021. The primary efficacy outcome was complete or near-complete aneurysm occlusion at 6 months (O'Kelly-Marotta, OKM, C-D, adapted for magnetic resonance angiography). Safety outcomes included 30-day major morbidity defined as modified Rankin Score (mRS) 3-5, mortality, serious adverse events and procedural complications.

RESULTS

A total of 21 large diameter DEDs were deployed in 18 patients (age 59.5 ± 14.1 years), harboring 19 unruptured aneurysms. Of the aneurysms 14 (73.7%) were saccular in morphology (sac diameter 10.9 ± 5.5 mm, neck diameter 6.8 ± 3.1 mm), 3 (15.8%) aneurysms were dissecting, 1 (5.3%) iatrogenic pseudoaneurysm and 1 (5.3%) fusiform. Aneurysm locations were: ICA (internal carotid artery) (n = 17); (7 cavernous, 4 paraophthalmic, 2 paraclinoid, 1 petrous, 2 communicating, 1 cervical); vertebrobasilar (n = 2). Adjunct stenting to optimize proximal wall apposition was undertaken in 5 (27.8%) patients. At 6 months 75% of patients followed-up met the primary efficacy endpoint (OKM C-D). There were no serious adverse events, 30-day major morbidity (mRS 3-5) or mortality.

CONCLUSION

Implantation of large diameter (5.5 mm and 6 mm) DEDs into capacious cerebral vessels to treat a range of complex aneurysms is safe and technically feasible but may require adjunct stenting to optimize proximal wall apposition. Short-term efficacy of this device subset is comparable to previous DED and other flow diverter studies. Long-term follow-up and comparative studies are required for further assessment.

Early clinical experience with the p48MW HPC and p64MW HPC flow diverters in the anterior circulation aneurysm using single anti-platelet treatment

Background

The p64MW HPC and p48MW HPC flow diverters have reduced thrombogenicity due to hydrophilic coating. The purpose of this study was to evaluate its safety and efficacy in Mongolian patients under single antiplatelet therapy (SAPT) with prasugrel.

Materials and methods

We performed a retrospective review of patients enrolled into our prospectively maintained database to identify all patients treated with either the p48MW HPC or p64MW HPC under SAPT. We recorded baseline demographics, aneurysm size and location, procedural complications, angiographic and clinical results.

Results

24 patients, (female = 21, 87.5%), age 48.2 ± 11.6 years (range 25–63) underwent treatment of 30 aneurysms with either p64MW HPC or p48MW HPC. All aneurysms were saccular with dome width 8.2 ± 6.5 (range 1.6–26.0 mm) and dome height 7.6 ± 6.7 (range 1.6–30.0 mm). None of the aneurysms were previously treated. The average PRU was 54.6 ± 31.2 (range 1–127) on pre-operative VerifyNow testing. Angiographic follow-up was available for 13 patients (17 aneurysms), 183 ± 36 days post-procedure, at which point 64.7% of aneurysms (n = 11/17) were completely occluded and 11.8% (n = 2/17) had only neck remnants resulting in 76.5% of aneurysms being adequately occluded A single intra-operative complication (4.2%) occurred however all patients were mRS ≤1 at last follow-up. There were two post-operative complications neither of which resulted in permanent neurological morbidity. There were no instances of post-operative aneurysmal rupture or delayed parenchymal haemorrhage. The overall mortality was 0%.

Conclusion

The efficacy and safety of p64MW HPC coated devices under SAPT is similar to uncoated flow diverters that require DAPT.

Flow-diverting device versus coil embolization for unruptured intracranial aneurysm: A meta-analysis

BACKGROUND

Both coil embolization (CE) and flow-diverting device (FDD) placement are widely used for treatment of intracranial aneurysms (IAs). The aim of this meta-analysis is to compare the relative clinical safety and efficacy of FDD and CE for the treatment of unruptured IAs.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched for relevant studies from the date of inception through April 2020. The primary endpoint for this meta-analysis was the 6-month rate of complete occlusion, while secondary endpoints included rates of retreatment, complications, and parental arterial patency.

RESULTS

This meta-analysis includes 8 studies, which included 839 total patients that underwent FDD and 2734 that underwent CE. FDD group exhibited a significantly higher pooled 6-month complete occlusion rate (P = .02). The subgroup analysis demonstrated that FDD treatment was associated with significantly higher pooled 6-month complete occlusion rates in patients with large or giant IAs (P < .00001), whereas no differences in 6-month complete occlusion rates were observed between the FDD and CE groups of patients with non-large/giant IAs (P = .83). The pooled retreatment (P = .16) and complication (P = .15) rates were comparable between 2 groups. The CE group exhibited significantly higher pooled parent artery patency rate (P = .01). The funnel plots did not reveal any evidence of publication bias.

CONCLUSIONS

FDDs can be used to effectively and safely treat large and giant IAs, achieving higher rates of complete occlusion than CE treatment. For non-large/giant IAs, we observed comparable efficacy between FDD and CE treatments.

Postoperative occlusion degree after flow-diverter placement with adjunctive coiling: analysis of complications

BACKGROUND

Although coiling with a flow diverter may provide immediate dome protection, no studies have evaluated the effect on complications of postoperative occlusion degree immediately postoperatively. The purpose of this study was to determine whether postoperative occlusion degree immediately after flow-diverter placement with adjunctive coiling was associated with complications.

METHODS

All patients' data were collected from the post-market multi-center cohort study of embolization of intracranial aneurysms with a pipeline embolization device (PED) in China (PLUS) registry. We divided patients into those treated with a PED alone (PED-only (PO) group), those treated with a PED with coils and incomplete occlusion (PED + coils + incomplete occlusion (PCIO) group), and those treated with a PED with coils and complete occlusion (PED + coils + complete occlusion (PCCO) group).

RESULTS

We evaluated 1171 consecutive patients with 1322 aneurysms treated with a PED: 685 aneurysms were treated with PO, 444 with PCIO, and 193 with PCCO. The PCCO group had a higher rate of aneurysm occlusion at the last follow-up than the PCIO and PO groups (P<0.0001). Multivariate analysis of the predictors of ischemic stroke and modified Rankin Scale score (mRS) deterioration showed that PCCO was an independent predictor of ischemic stroke (HR, 2.03; 95% CI, 1.12 to 3.67; P=0.019) and mRS deterioration (HR, 2.59; 95% CI, 1.57 to 4.26; P<0.0001).

CONCLUSIONS

Although postoperative complete occlusion with a PED and adjunctive coiling can increase the rate of aneurysm occlusion, this approach may also increase the risk of ischemic stroke and lead to poor postoperative functional outcomes.

Imbalanced flow changes of distal arteries: An important factor in process of delayed ipsilateral parenchymal hemorrhage after flow diversion in patients with cerebral aneurysms

BACKGROUND AND OBJECTIVE

Hemodynamic forces may play a role in symptomatic delayed ipsilateral parenchymal hemorrhage (DIPH) of intracranial aneurysm (IA) after flow diverter placement. We aimed to investigate the hemodynamic risk factors in the postsurgical DIPH process.

METHODS

Six patients with internal carotid artery (ICA) aneurysm developed to DIPH and 12 patients without DIPH (1:2 matched controls) after flow diverter were included between January 2015 to January 2019. Postsurgical hemodynamics of distal arteries (terminal ICA, middle cerebral artery (MCA), anterior cerebral artery (ACA)) were investigated using computational fluid dynamics, as well as the hemodynamic alteration between pre- and post-treatment. The DIPH related and unrelated distal arteries (either MCA or ACA) were discriminated and compared. Definition of imbalance index is the difference in increased velocity post-flow diverter between MCA and ACA and was used to evaluate the blood flow distribution of distal arteries.

RESULTS

The mean and maximum flow velocities in the terminal ICA increased significantly after treatment in both groups. In DIPH group, the increase rate of mean velocity in the DIPH-related artery was significantly higher than that in DIPH-unrelated artery after the treatment (20.98 ± 15.38% vs -6.40 ± 7.74%; p = 0.028). Between the DIPH and control group, the baseline characteristics were well matched. However, a higher imbalance index of mean velocity was found in DIPH group (27.38 ± 13.03% vs 10.85 ± 14.12%; p = 0.031).

CONCLUSION

The mean velocity of DIPH related artery increased more, and the imbalance in increased blood flow distribution of distal arteries might play an important role in DIPH after flow diverter of IAs.

Optical coherence tomography for elucidation of flow-diversion phenomena: The concept of endothelized mural thrombus behind reversible in-stent stenosis in flow-diverters

PURPOSE

Flow-diverters have revolutionized the endovascular treatment of intracranial aneurysms, offering a durable solution to aneurysms with high recurrence rates after conventional stent-assisted coiling. Events that occur after treatment with flow-diversion, such as in-stent stenosis (ISS) are not well understood and require further assessment. After assessing an animal model with Optical Coherence Tomography (OCT), we propose a concept that could explain the mechanism causing reversible ISS after treatment of intracranial aneurysms with flow-diverters.

METHODS

Six Pipeline Flex embolization devices (PED-Flex), six PED with Shield technology (PED-Shield), and four Solitaire AB devices were implanted in the carotid arteries (two stents per vessel) of four pigs. Intravascular optical coherence tomography (OCT) and digital subtraction angiography (DSA) images obtained on day 21 were compared to histological specimens.

RESULTS

A case of ISS in a PED-Flex device was assessed with OCT imaging. Neointima with asymmetrical topography completely covering the PED struts was observed. Histological preparations of the stenotic area demonstrated thrombus on the surface of device struts, covered by neointima.

CONCLUSION

This study provides a plausible concept for reversible ISS in flow-diverters. Based on an observation of a previous experiment, we propose that similar cases of ISS are related to thrombus presence underneath endothelization, but further experiments focused on this phenomenon are needed. Optical Coherence Tomography will be useful tool when available for clinical use.

Flow diverter stents in the treatment of recanalized intracranial aneurysms

BACKGROUND

We assessed the safety and efficacy of flow diverter stents (FDSs) in the treatment of recanalized or residual intracranial aneurysms treated endovascularly.

MATERIALS & METHODS

Patients whose recanalized or residual aneurysms were treated with FDSs in five tertiary hospitals were reviewed retrospectively. The patients' demographic data, aneurysm characteristics, types of previous treatment, and clinical complications, or serious adverse events associated with FDSs, as well as the results of neurological and angiographic follow-up assessments, were recorded.

RESULTS

Eighty-six patients (37 males) with 87 aneurysms were included in this study. Eighty (91.9%) aneurysms were in the anterior and seven (8.1%) in the posterior circulation. The initial treatment methods were the primary coiling or balloon remodeling technique in 69 (79.3%) and stent-assisted coiling in 18 (20.7%) aneurysms. The endovascular procedure was successful in all patients. Complications occurred in four patients, for a total complication rate of 4.6%. A technical complication developed in one patient (1.2%). An in-stent thrombosis treated with tirofiban was seen in two cases. Late in-stent stenosis exceeding 50% was treated with balloon angioplasty in one patient. The mean length of follow-up was 21.0 months. The first angiographic follow-up (3-6 months) revealed the complete occlusion of 74 aneurysms (85.1%). While 76 aneurysms (87.4%) were occluded at the last angiographic follow-up (mean: 26.0 months), 11 aneurysms (12.6%) were still filling. Morbimortality was zero.

CONCLUSION

The drawback of endovascular treatment is aneurysmal remnants or recurrences, which is safely and durably amenable to flow diversion.

The Enterprise2 Stent for Endovascular Treatment of Intracranial Aneurysms: Short-Term Results From a Single Center Experience

Background: Self-expanding devices, such as the Enterprise VRD (EP-VRD) have widely used for stent-assisted coiling treatment in wided-necked aneuryms while some thromboembolic complications were reported due to its incomplete stent apposition (ISA). We report our experiences on the novel Enterprise2 (EP-VRD2) stent in vivo in the treatment of intracranial and cranial cervical junction aneurysms.

Methods: Twenty-five consecutive patients with intracranial or cranial cervical junction aneurysms were treated with EP-VRD2 stents retrospectively collected in our institution. We use the ‘jailing' technique in all cases and deployed the stent by using pushing over the outer curve technique. The 3- or 6-monthS follow-up was done regularly by DSA.

Results: Twenty-five EP-VRD2 stents were implanted to treat 21 aneurysms at the siphon segment of internal carotid artery (ICA), one at the petrous segment, two at the cervical segment, one at the verteral artery with five accompanied with stenosis. Two patients had kinking during the procedure and were solved by microwire or microcatheter massaging. Four patients with a larger arc angle and a smaller radius of the parent vessel was detected ISA. No patient underwent the ischemic event after the operation. Twenty-three of 25 patients were evaluated after 3- or 6-months by DSA, 22 showed complete occlusion (RROC1), one slight re-stenosis in the follow-up within those five patients with stenosis. A length of 23 mm seemed associated with ISA (p < 0.01).

Conclusion: The EP-VRD2 performed well in our small patient series; however, ISA could still occur with a sharp angle of the parent vessel.

Expanding Indications for Flow Diverters: Distal Aneurysms, Bifurcation Aneurysms, Small Aneurysms, Previously Coiled Aneurysms and Clipped Aneurysms, and Carotid Cavernous Fistulas

Flow diverter devices have gained wide acceptance for the treatment of unruptured intracranial aneurysms. Most studies are based on the treatment of large aneurysms harboring on the carotid syphon. However, during the last years the “off-label” use of these stents has widely grown up even if not supported by randomized studies. This review examines the relevant literature concerning “off-label” indications for flow diverter devices, such as for distal aneurysms, bifurcation aneurysms, small aneurysms, recurrent aneurysms, and direct carotid cavernous fistulas.

Longitudinal Monitoring of Flow-Diverting Stent Tissue Coverage After Implant in a Bifurcation Model Using Neurovascular High-Frequency Optical Coherence Tomography

BACKGROUND

Tissue growth over covered branches is a leading cause of delayed thrombotic complications after flow-diverter stenting (FDS). Due to insufficient resolution, no imaging modality is clinically available to monitor this phenomenon.

OBJECTIVE

To evaluate high-frequency optical coherence tomography (HF-OCT), a novel intravascular imaging modality designed for the cerebrovascular anatomy with a resolution approaching 10 microns, to monitor tissue growth over FDS in an arterial bifurcation model.

METHODS

FDS were deployed in a rabbit model (n = 6), covering the aortic bifurcation. The animals were divided in different groups, receiving dual antiplatelet therapy (DAPT) (n = 4), aspirin only (n = 1), and no treatment (n = 1). HF-OCT data were obtained in vivo at 3 different time points in each animal. For each cross-sectional image, metal and tissue coverage of the jailed ostium was quantified. Scanning electron microscopy images of harvested arteries were subsequently obtained.

RESULTS

Good quality HF-OCT data sets were successfully acquired at implant and follow-up. A median value of 41 (range 21-55) cross-sectional images were analyzed per ostium for each time point. Between 0 and 30 d after implant, HF-OCT analysis showed a significantly higher ostium coverage when DAPT was not given. After 30 d, similar growth rates were found in the DAPT and in the aspirin group. At 60 d, a coverage of 90% was reached in all groups.

CONCLUSION

HF-OCT enables an accurate visualization of tissue growth over time on FDS struts. The use of FDS in bifurcation locations may induce a drastic reduction of the jailed-branch ostium area.

A Novel Parameter to Predict Supraclinoid Aneurysm Persistence After Flow Diversion with the Pipeline Embolization Device

BACKGROUND

Aneurysm recurrence after Pipeline Embolization Device (PED) placement can be caused by oversizing of the stent as well as poor wall apposition, both of which can lead to elongation. The objective of this study was to assess whether a novel parameter for measuring device elongation based on two-dimensional imaging could be predictive for persistent aneurysm filling after treatment with the PED.

METHODS

A retrospective cohort analysis was initially completed on 41 aneurysms from institution A, examining demographic, aneurysmal, and device measurements. Device measurements, including the ratio of the measured length to the nominal length (ML/NL) of the PED, were taken by reviewers blinded to the primary end point, which was aneurysm occlusion status on 6 month catheter angiogram. Findings were then externally validated against 30 aneurysms (supraclinoid only) from institution B.

RESULTS

Data from institution A showed 61% complete aneurysm occlusion at 6 months, and were lower for aneurysms in the supraclinoid region. For supraclinoid aneurysms alone, combined data from both institutions showed higher rates of nonocclusion with aneurysm neck size >4 mm (P = 0.008) and a trend toward significance in aneurysms with a branch vessel (P = 0.051). The mean ML/NL ratio was significantly larger in the nonoccluded group compared with the occluded group at both institution A (ratio, 1.37 versus 1.10; P < 0.001) and institution B (ratio, 1.36 vs. 1.11; P = 0.002).

CONCLUSIONS

Our data suggest that a novel parameter based on two-dimensional angiography may serve as a rapid technique to measure device elongation and predict occlusion of supraclinoid aneurysms after PED placement.

Multicenter Study of Pipeline Flex for Intracranial Aneurysms

BACKGROUND

The Pipeline Flex (PED Flex; Medtronic, Dublin, Ireland) was designed to facilitate deployment and navigation compared to its previous iteration to reduce the rate of technical events and complications.

OBJECTIVE

To assess the neurological morbidity and mortality rates of the PED Flex at 30 d.

METHODS

Information from 9 neurovascular centers was retrospectively obtained between July 2014 and March 2016. Data included patient/aneurysm characteristics, periprocedural events, clinical, and angiographic outcomes. Multivariate logistic regression was performed to determine predictors of unfavorable clinical outcome (modified Rankin Scale [mRS] > 2).

RESULTS

A total of 205 patients harboring 223 aneurysms were analyzed. The 30-d neurological morbidity and mortality rates were 1.9% (4/205) and 0.5% (1/205), respectively. The rate of intraprocedural events without neurological morbidity was 6.8% (14/205), consisting of intraprocedural ischemic events in 9 patients (4.5%) and hemorrhage in 5 (2.4%). Other technical events included difficulty capturing the delivery wire in 1 case (0.5%) and device migration after deployment in another case (0.5%). Favorable clinical outcome (mRS 0-2) was achieved in 186 patients (94.4%) at discharge and in 140 patients (94.5%) at 30 d. We did not find predictors of clinical outcomes on multivariate analysis.

CONCLUSION

The 30-d rates of neurological morbidity and mortality in this multicenter cohort using the PED Flex for the treatment of intracranial aneurysms were low, 1.9% (4/205) and 0.5% (1/205), respectively. In addition, technical events related to device deployment were also low, most likely due to the latest modifications in the delivery system.

The Evolution of Flow-Diverting Stents for Cerebral Aneurysms; Historical Review, Modern Application, Complications, and Future Direction

In spite of the developing endovascular era, large (15–25 mm) and giant (>25 mm) wide-neck cerebral aneurysms remained technically challenging. Intracranial flow-diverting stents (FDS) were developed to address these challenges by targeting aneurysm hemodynamics to promote aneurysm occlusion. In 2011, the first FDS approved for use in the United States market. Shortly thereafter, the Pipeline of Uncoilable or Failed Aneurysms (PUFS) study was published demonstrating high efficacy and a similar complication profile to other intracranial stents. The initial FDA instructions for use (IFU) limited its use to patients 22 years old or older with wide-necked large or giant aneurysms of the internal carotid artery (ICA) from the petrous segment to superior hypophyseal artery/ophthalmic segment. Expanded IFU was tested in the Prospective Study on Embolization of Intracranial Aneurysms with PipelineTM Embolization Device (PREMIER) trial. With further post-approval clinical data, the United States FDA expanded the IFU to include patients with small or medium, wide-necked saccular or fusiform aneurysms from the petrous ICA to the ICA terminus. However, IFU is more restrictive in South Korea than in United States. Several systematic reviews and meta-analyses have sought to evaluate the overall efficacy of FDS for the treatment of cerebral aneurysms and consistently identify FDS as an effective technique for the treatment of aneurysms broadly with complication rates similar to other traditional techniques. A growing body of literature has demonstrated high efficacy of FDS for small aneurysms; distal artery aneurysms; non-saccular aneurysms posterior circulation aneurysms and complication rates similar to traditional techniques. In the short interval since the Pipeline Embolization Device was first introduced, FDS has been firmly entrenched as a powerful tool in the endovascular armamentarium. As new FDS are developed, established FDS are refined, and delivery systems are improved the uses for FDS will only expand further. Researchers continue to work to optimize the mechanical characteristics of the FDS themselves, aiming to optimize deploy ability and efficacy. With expanded use for small to medium aneurysms and posterior circulation aneurysms, FDS technology is firmly entrenched as a powerful tool to treat challenging aneurysms, both primarily and as an adjunct to coil embolization. With the aforementioned advances, the ease of FDS deployment will improve and complication rates will be further minimized. This will only further establish FDS deployment as a key strategy in the treatment of cerebral aneurysms.

Future Directions of Flow Diverter Therapy

The treatment of intracranial aneurysms has undergone a few very significant paradigm shifts in its history. Needless to say, microsurgery and surgical clipping served as the initial basis for successful treatment of these lesions. The pursuit of endovascular therapy subsequently arose from the desire to reduce the invasiveness of therapy. While the first breakthrough arose with Guido Guglielmi's invention of the detachable platinum coil, commercialized flow diverter therapy represents a disruptive therapy with a completely different paradigm for aneurysmal obliteration. This has not only altered the distribution of aneurysmal management strategies, but also opened the gateway to the treatment of previously inoperable lesions. With the basic flow diverter stent technology now considered an integral part of the neurointerventional armamentarium, we now consider what may lay in the future - including potential directions for research with regards to case selection; the location and type of aneurysms which may become routinely treatable; and modifications to the flow diverter, which may increase its utility and safety in terms of size, structural design, and surface modifications.

Expanding Indications for Flow Diverters: Ruptured Aneurysms, Blister Aneurysms, and Dissecting Aneurysms

BACKGROUND

The safety and efficacy of flow diversion (FD) in the treatment of cerebral aneurysms have been reported by many studies. FD has enabled the treatment of complex aneurysms and aneurysms that were previously untreatable by conventional means. It has achieved high rates of obliteration with essentially no recanalization, and its indications have continued to expand, now including ruptured aneurysms, blister aneurysms, and dissecting aneurysms.

OBJECTIVE

To provide a review on the outcomes of studies covering the use of FD in the settings of ruptured, blister, and dissecting aneurysms. In addition, to discuss dual antiplatelet therapy (DAPT) used in preparation for FD deployment in these scenarios, including associated complications with DAPT use in the acute rupture setting.

METHODS

References for this topical review were identified by PubMed searches between January 2000 and January 2019. The search terms “aneurysm”, “flow diverter”, “stent”, “pipeline”, “ruptured”, “blister”, and “dissecting aneurysms” were used.

RESULTS

FD carries a higher complication rate in the acute rupture setting than for unruptured aneurysms. Patient selection is of paramount importance for achieving good functional and angiographic outcomes. DAPT still remains challenging, especially in ruptured aneurysms. Advancements in surface modification of flow diverters can reduce the risk of thromboembolism and perhaps lead to a safer antiplatelet regimen.

CONCLUSION

In summary, FD shows promise to be an effective treatment for ruptured, blister, and dissecting aneurysms.

Neuroendovascular surgery

Neuroendovascular surgery and interventional neuroradiology both describe the catheter-based (most often) endovascular diagnosis and treatment of vascular lesions affecting the brain and spinal cord. This article traces the evolution of these techniques and their current role as the dominant and frequently standard approach for many of these conditions. The article also discusses the important changes that have been brought to bear on open cerebrovascular neurosurgery by neuroendovascular surgery and their effects on resident and fellow training and describes new concepts for clinical care.

Flow diversion treatment of complex bifurcation aneurysms beyond the circle of Willis: complications, aneurysm sac occlusion, reabsorption, recurrence, and jailed branch modification at follow-up

OBJECTIVE

The purpose of this study is to present the authors' medium-term results, with special emphasis on complications, occlusion rate of the aneurysm sac (digital subtraction angiography [DSA] and MRI), and the fate of cortical branches and perforating arteries covered ("jailed") by the flow diverter (FD) stent.

METHODS

Between January 2010 and September 2017, 29 patients (14 female) with 30 aneurysms were treated with an FD stent. Twenty-one aneurysms were at the middle cerebral artery bifurcation, 8 were in the anterior communicating artery region, and 1 was a pericallosal artery bifurcation. Thirty-five cortical branches were covered. A single FD stent was used in all patients. Symptomatic and asymptomatic periprocedural and delayed complications were reported. DSA and MRI controls were analyzed to evaluate modification of the aneurysm sac and jailed branches.

RESULTS

Permanent morbidity was 3.4% (1/29), due to a jailed branch occlusion, with a modified Rankin Scale (mRS) score of 2 at the last follow-up. Mortality and permanent complication with poor prognosis (mRS score > 2) rates were 0%. The mean follow-up time for DSA and MRI (mean ± SD) was 21 ± 14.5 months (range 3-66 months) and 19 ± 16 months (range 3-41 months), respectively. The mean time to aneurysm sac occlusion (available for 24 patients), including stable remodeling, was 11.8 ± 6 months (median 13, range 3-27 months). The overall occlusion rate was 82.1% (23/28), and it was 91.7% (22/24) in the group of patients with at least 2 DSA control sequences. One recanalization occurred at 41 months posttreatment. At the time of publication, at the latest follow-up, 7 (20%) of 35 covered branches were occluded, 18 (51.4%) showed a decreased caliber, and the remaining 10 (28.5%) were unchanged. MRI T2-weighted sequences showed complete sac reabsorption in 7/29 aneurysms (24.1%), and the remaining lesions were either smaller (55.2%) or unchanged (17.2%). MRI revealed asymptomatic and symptomatic ischemic events in perforator territories in 7/28 (25%) and 4/28 (14.3%) patients, respectively, which were reversible within 24 hours.

CONCLUSIONS

Flow diversion of bifurcation aneurysms is feasible, with low rates of permanent morbidity and mortality and high occlusion rates; however, recurrence may occur. Caliber reduction and asymptomatic occlusion of covered cortical branches as well as silent perforator stroke are common. Ischemic complications may occur with no identified predictable factors. MRI controls should be required in all patients to evaluate silent ischemic lesions and aneurysm sac reabsorption over time.

One and done? The effect of number of Pipeline embolization devices on aneurysm treatment outcomes

BACKGROUND

Controversy exists regarding the optimum number of flow diverters for the treatment of intracranial aneurysms. We explored the effect of the number of Pipeline embolization devices (PEDs; Medtronic, Dublin, Ireland) deployed on rates of aneurysm occlusion and complications.

METHODS

Consecutive patients who underwent saccular intracranial aneurysm treatment solely with the PED were included in this retrospective study. Computed tomographic, magnetic resonance, or digital subtraction angiographic images at 6 and 12 months and last follow-up (>12 months) were reviewed for aneurysm occlusion. Complication and retreatment rates were recorded and analyzed statistically.

RESULTS

The study included 141 aneurysm treatments in 119 patients. A single PED was deployed in 105 cases, two PEDs in 31 cases, and three PEDs in 5 cases (total = 182 devices). Six-month angiographic data were available for 103 patients. Occlusion rates were 67.1% for single-PED cases and 90.0% for cases with > 1 PED (p = 0.028). The 12-month occlusion rate (follow-up available for 132) for single-PED cases was 74.7% compared to 91.7% for multiple-PED cases (p = 0.04). On multivariate analysis, number of PEDs was an independent predictor of aneurysm occlusion at 12 months (odds ratio 6.3, 95% confidence interval 1.8-22.8, p = 0.005). Thromboembolic complication rates were the same in the single- and multiple-PED treatment groups (2.8%). The retreatment rate was higher in patients treated with a single PED (16.2% vs. 0%, p = 0.01).

CONCLUSIONS

Deployment of > 1 Pipeline embolization device was associated with higher intracranial aneurysm occlusion and lower retreatment rates. No significant difference was found in complication rates.

Preliminary in vitro angiographic comparison of the flow diversion behavior of Evolve and Pipeline devices

Background and purpose

Flow diverters are increasingly used to treat a broad category of cerebral aneurysms. We conducted an in vitro study to angiographically compare the flow diversion effect of Surpass Evolve from Stryker Neurovascular with the Pipeline Shield Embolization Device from Medtronic Neurovascular.

Methods

Three copies each of three carotid aneurysm geometries were manufactured from silicone. Evolve and Pipeline flow diverters were deployed in one copy of each geometry; the third copy was used as Control. High-speed angiography was acquired under pulsatile flow in each replica, contrast concentration-time curves within the aneurysms were recorded, and the curves were quantified with six parameters. The parameters were statistically evaluated to compare the flow diversion effect of both devices.

Results

The Evolve showed greater flow diversion trends in almost all intra-geometry comparisons than the Pipeline. When aggregated over the three geometries, the Evolve was statistically significantly better than the Pipeline in four of the six parameters, and about the same or better (not statistically significant) than the Pipeline in the other two parameters.

Conclusions

The Evolve device demonstrated greater in vitro flow diversion effects than Pipeline. Comparative efficacy of the devices will need to be adjudicated based on clinical outcomes.

Prospective study on embolization of intracranial aneurysms with the pipeline device: the PREMIER study 1 year results

Background

Preliminary clinical studies on the safety and efficacy of the pipeline embolization device (PED) for the treatment of small/medium aneurysms have demonstrated high occlusion rates with low complications.

Objective

To evaluate the safety and effectiveness of the PED for treatment of wide necked small and medium intracranial aneurysms.

Methods

PREMIER is a prospective, multicenter, single arm trial. Patients were treated with the PED for unruptured wide necked aneurysms, measuring ≤12 mm along the internal carotid artery or vertebral artery, between July 2014 and November 2015. At 1 year post-procedure, the primary effectiveness endpoint was complete occlusion (Raymond grade 1) without major parent vessel stenosis (≤50%) or retreatment, and the primary safety endpoint was major stroke in the territory supplied by the treated artery or neurologic death.

Results

A total of 141 patients were treated with PEDs (mean age 54.6±11.3 years, 87.9% (124/141) women). Mean aneurysm size was 5.0±1.92 mm, and 84.4% (119/141) measured <7 mm. PED placement was successful in 99.3% (140/141) of patients. Mean number of PEDs implanted per patient was 1.1±0.26; a single PED was used in 92.9% (131/141) of patients. At 1 year, 97.9% (138/141) of patients underwent follow-up angiography with 76.8% (106/138) of patients having met the study’s primary effectiveness endpoint. The combined major morbidity and mortality rate was 2.1% (3/140).

Conclusions

Treatment of wide necked small/medium aneurysms with the PED results in high rates of complete occlusion without significant parent vessel stenosis and low rates of permanent neurologic complications.

Trial registration

NCT02186561.

Flow diversion for small caliber vessel aneurysms: efficacy, safety, and functional outcome

BACKGROUND

Flow-diverting stents had gained prominence among neurointerventionalists. Aneurysms originating from distal vessels, particularly dissecting or fusiform, pose more technical challenges. The aim of the following single center large series was to report the safety, efficacy, and functional outcome of flow diversion for aneurysms originating from small caliber vessel and compare to proximal vessels group.

METHODS

A retrospective chart review of a prospectively maintained database for subjects treated with flow diversion from 2010-2019.

RESULTS

A total of 598 aneurysms were treated during a period extending from 2010-2019 (87.8% large caliber group versus 12.20% small caliber group); 84.28% (N.=504) were females and the average age was 55.5 years. Ischemic stroke occurred at a rate of 2.99% with a non-significant difference between both groups. Delayed aneurysmal rupture and distal intraparenchymal bleed occurred at a rate of 3.70% with a non-significant difference between both groups. Complete aneurysms occlusion was seen at a rate of 75.3% with a non-significant difference between both groups. Morbidity rate occurred at a rate of 5.8% with non-significant difference between both groups. Multivariate logistic regression showed that small vessel was an independent predictor of aneurysm obliteration with a 2.6-fold-higher likelihood.

CONCLUSIONS

Flow-diverting stents are being used to treat diverse types of aneurysms and in various locations, in distal small caliber vessels where other treatment options pose a considerable risk. Small caliber group had similar complication and occlusion rates compared to proximal vessel group.

Exploring the Feasibility of Pipeline Embolization Device Compared With Stent-Assisted Coiling to Treat Non-saccular, Unruptured, Intradural Vertebral Artery Aneurysms

Object: The pipeline embolization device (PED) has been used to treat non-saccular, unruptured, intradural vertebral artery aneurysms at some institutions. However, there is an absence of large controlled studies validating the feasibility of this treatment. This study aimed to explore the therapeutic feasibility of PED by comparing PED treatment with controlled stent-assisted coiling (SAC).

Materials and Methods: Thirty-two PED procedures were matched in a 1:2 manner with 64 SAC procedures based on patient age, sex, aneurysm size, and aneurysm location. Technical factors, procedural complications, angiographic results, and clinical outcomes were analyzed and compared.

Results: There was no statistically significant difference in technical factors and procedural complications between the two groups (PED vs. SAC, 9.4 vs. 4.7%, P = 0.397). In multivariate analysis, smoking and therapeutic modality were identified as independent predictors of occlusion. Smoking was a risk factor for aneurysm obliteration [hazard ratio (HR) 0.53; 95% confidence interval (CI), 0.31–0.89; P = 0.018]. Aneurysms treated with PED were more likely to achieve obliteration over time compared with aneurysms treated with SAC (HR 2.97; 95% CI, 1.79–4.93; P < 0.001). The rate of favorable clinical outcomes (modified Rankin Scale (mRS), 0–2) was similar between the two groups (PED vs. SAC, 100 vs. 96.9%, P = 0.551). In the SAC group, one patient had neurological deficit with an mRS of four at the latest follow-up. There was no mortality in either group.

Conclusions: The PED and SAC groups showed similar technical factors, procedural complications, angiographic results, and favorable clinical outcomes. Aneurysms treated with PED were more prone to obliteration over time than aneurysms treated with SAC. These outcomes suggest, based on short-term follow-up, PED is a safe and feasible strategy for the treatment of non-saccular, unruptured, intradural vertebral artery aneurysms.

Pipeline for Distal Cerebral Circulation Aneurysms

BACKGROUND

Pipeline embolization device (PED; Medtronic, Dublin, Ireland) utilization is not limited to the treatment of giant wide-necked aneurysms. It has been expanded to handle small blisters, fusiforms, and dissecting intracranial aneurysms.

OBJECTIVE

To report the use of the PED in various off-label distal cerebral circulation (DCC) arteries with a follow-up to assess clinical outcomes.

METHODS

Between 2011 and 2016, of 437 consecutive patients, 23 patients with aneurysms located in DCCs were treated with PED. Data on patient presentation, aneurysm characteristics, procedural outcomes, postoperative course, and aneurysm occlusion were gathered. To control confounding, we used multivariable logistic regression and propensity score conditioning.

RESULTS

A total of 437 patients (mean age 52.12 years; 62 women [14.2%]) underwent treatment with PED in our institution. Twenty-three of 437 (5.2%) received a pipeline in a distal artery: 11/23 middle cerebral artery, 6/23 posterior cerebral artery, 3/23 anterior cerebral artery (A1/A2, pericallosal artery), and 3/23 posterior inferior cerebellar artery. Twenty percent of the aneurysms were treated in the past, 10% had previously ruptured, and 5.9% ruptured at presentation to our hospital. The mean aneurysm size was 9.0 ± 6 mm. The mean follow-up was 12 mo (SD = 12.5). In multivariable logistic regression, no associations were found between PED deployment in DCCs and aneurysm occlusion or thromboembolic complications. PED use in DCC was associated with a good clinical outcome. Twenty-two people of 23 (95%) had a good clinical outcome in the latest follow-up.

CONCLUSION

Treatment of DCC aneurysms with PED is technically challenging mainly because of the small caliber and tortuosity of the parent arteries. The results of this study further support the safety of flow diverters in the treatment of various distal aneurysms.

Procedural Clinical Complications, Case-Fatality Risks, and Risk Factors in Endovascular and Neurosurgical Treatment of Unruptured Intracranial Aneurysms: A Systematic Review and Meta-analysis

Importance

The risk of procedural clinical complications and the case-fatality rate (CFR) from preventive treatment of unruptured intracranial aneurysms varies between studies and may depend on treatment modality and risk factors.

Objective

To assess current procedural clinical 30-day complications and the CFR from endovascular treatment (EVT) and neurosurgical treatment (NST) of unruptured intracranial aneurysms and risk factors of clinical complications.

Data Sources

We searched PubMed, Excerpta Medica Database, and the Cochrane Database for studies published between January 1, 2011, and January 1, 2017.

Study Selection

Studies reporting on clinical complications, the CFR, and risk factors, including 50 patients or more undergoing EVT or NST for saccular unruptured intracranial aneurysms after January 1, 2000, were eligible.

Data Extraction and Synthesis

Per treatment modality, we analyzed clinical complication risk and the CFR with mixed-effects logistic regression models for dichotomous data. For studies reporting data on complication risk factors, we obtained risk ratios (RRs) or odds ratios (ORs) with 95% CIs and pooled risk estimates with weighted random-effects models.

Main Outcomes and Measures

Clinical complications within 30 days and the CFR.

Results

We included 114 studies (106 433 patients with 108 263 aneurysms). For EVT (74 studies), the pooled clinical complication risk was 4.96% (95% CI, 4.00%-6.12%), and the CFR was 0.30% (95% CI, 0.20%-0.40%). Factors associated with complications from EVT were female sex (pooled OR, 1.06 [95% CI, 1.01-1.11]), diabetes (OR, 1.81 [95% CI, 1.05-3.13]), hyperlipidemia (OR, 1.76 [95% CI, 1.3-2.37]), cardiac comorbidity (OR, 2.27 [95% CI, 1.53-3.37]), wide aneurysm neck (>4 mm or dome-to-neck ratio >1.5; OR, 1.71 [95% CI, 1.38-2.11]), posterior circulation aneurysm (OR, 1.42 [95% CI, 1.15-1.74]), stent-assisted coiling (OR, 1.82 [95% CI, 1.16-2.85]), and stenting (OR, 3.43 [95% CI, 1.45-8.09]). For NST (54 studies), the pooled complication risk was 8.34% (95% CI, 6.25%-11.10%) and the CFR was 0.10% (95% CI, 0.00%-0.20%). Factors associated with complications from NST were age (OR per year increase, 1.02 [95% CI, 1.01-1.02]), female sex (OR, 0.43 [95% CI, 0.32-0.85]), coagulopathy (OR, 2.14 [95% CI, 1.13-4.06]), use of anticoagulation (OR, 6.36 [95% CI, 2.55-15.85]), smoking (OR, 1.95 [95% CI, 1.36-2.79]), hypertension (OR, 1.45 [95% CI, 1.03-2.03]), diabetes (OR, 2.38 [95% CI, 1.54-3.67]), congestive heart failure (OR, 2.71 [95% CI, 1.57-4.69]), posterior aneurysm location (OR, 7.25 [95% CI, 3.70-14.20]), and aneurysm calcification (OR, 2.89 [95% CI, 1.35-6.18]).

Conclusions and Relevance

This study identifies risk factors for procedural complications. Large data sets with individual patient data are needed to develop and validate prediction scores for absolute complication risks and CFRs from EVT and NST modalities.

Low Yield of Cerebral Angiography in Adequately Occluded Aneurysms After Flow Diversion

BACKGROUND

Flow diversion has emerged as a highly effective treatment for intracranial aneurysms.

OBJECTIVE

To assess the yield of further angiographic follow-up in aneurysms that have achieved adequate occlusion after treatment with the Pipeline Embolization Device (PED; Medtronic Inc, Dublin, Ireland).

METHODS

This is a single-institution, retrospective study. Inclusion criteria were as follows: (1) patients with 1 or more aneurysms treated with PED, (2) available short-term (<12 mo) follow-up digital subtraction angiography (DSA), (3) complete (100%) or near-complete (>95%) occlusion on short-term follow-up DSA, and (4) available further angiographic follow-up (DSA, Magnetic Resonance Angiography (MRA), or Computed Tomography Angiography (CTA)).

RESULTS

A total of 146 patients were identified. Aneurysm size was 8.4 ± 5.1 mm on average. Mean angiographic follow-up time was 29.7 ± 12.2 mo. On short-term follow-up DSA images, 132 (90.4%) had complete aneurysm occlusion and 14 (9.6%) had near-complete occlusion. Four patients (3%) had further DSA follow-up alone, 30 patients (21%) had further DSA and MRA/CTA follow-up, and 112 patients (76%) had further MRA/CTA follow-up alone. On further angiographic follow-up (DSA, MRA, and/or CTA), no patient had a decrease in the degree of aneurysm occlusion (recurrence) or required retreatment. Of the 14 patients with near-complete occlusion on initial DSA images, 7 patients (50%) progressed to complete aneurysm occlusion on further angiographic follow-up.

CONCLUSION

This study did not find any diagnostic yield in repeating cerebral angiography in adequately occluded aneurysms with the PED. We do not recommend repeat angiographic follow-up once aneurysms have achieved complete occlusion with the PED unless clinically warranted.

The use of flow diverters to treat small (≤5 mm) ruptured, saccular aneurysms

Background:

There is limited published literature on the use of flow diverting stents (FDS) to treat ruptured intracranial aneurysms in the acute stage. We present our experience of using FDS to treat small (≤5 mm) ruptured aneurysms.

Methods:

We retrospectively identified all patients with ≤5 mm ruptured aneurysms treated exclusively with FDS between February 2009 and February 2016. We recorded demographic data, the Hunt and Hess score, aneurysm location and size, therapeutic intervention, immediate angiographic and clinical result, and clinical and radiological follow-up information.

Results:

We identified seven patients (four females) with average age 59.8 ± 10 years (range 48–75). The average aneurysm fundus size was 2.7 ± 0.76 mm (range 1–4 mm). The average time from ictus to treatment was 6.3 days (range 1–14 days) and there were no cases of repeat rupture prior to treatment or intraoperative rupture. Angiographic follow-up was available in five patients. At initial follow-up, aneurysms (100%) were completely occluded raymond roy classification 1 (RRC 1). None of the aneurysms re-ruptured following treatment. Clinically, six patients were discharged with good functional outcome modified Rankin Score (mRS ≤2). There were no mortalities.

Conclusion:

The use of FDS to treat small, ruptured, saccular aneurysms is feasible; however, the use of FDS should not be considered first-line treatment. Further studies are required to determine the safety and efficacy of the use of FDS in the acute situation.

Bailout Strategies and Complications Associated with the Use of Flow-Diverting Stents for Treating Intracranial Aneurysms

Background

Flow-diverting stents (FDS) have revolutionized the endovascular management of unruptured, complex, wide-necked, and giant aneurysms. There is no consensus on management of complications associated with the placement of these devices. This review focuses on the management of complications of FDS for the treatment of intracranial aneurysms.

Summary

We performed a systematic, qualitative review using electronic databases MEDLINE and Google Scholar. Complications of FDS placement generally occur during the perioperative period.

Key Message

Complications associated with FDS may be divided into periprocedural complications, immediate postprocedural complications, and delayed complications. We sought to review these complications and novel management strategies that have been reported in the literature.

Flow diversion versus parent artery occlusion with bypass in the treatment of complex intracranial aneurysms: Immediate and short-term outcomes of the randomized trial

OBJECTIVE

We performed prospective randomized comparison of clinical and surgical outcomes of flow diversion versus PVO and bypass in patients with complex anterior circulation aneurysms.

PATIENTS AND METHODS

Open, prospective, randomized, parallel group, multicenter study of complex intracranial aneurysms treatment was conducted. Patients with complex intracranial aneurysms of anterior circulation with neck is more than 4 mm wide, dome/neck ratio is equal or less than 2:1, which is suitable for flow diversion and occlusion with bypass were included in the study. A total of 111 potential participants were enrolled since March 2015. Additional propensity score matching was performed with 40 patients in each group selected for analysis.

RESULTS

39 out of 40 patients (97.5%) from matched FD group reached good clinical outcome. In the matched bypass group acceptable outcome was achieved in 32 (80%) out of 40 patients (difference between groups p = 0.029). The morbidity and mortality rates were 15% and 5%, respectively. Difference in the rates of favorable outcomes, compared by χ2 met statistical significance (p = 0.014). The rate of complete aneurysm occlusion at 6 months was 42.5% in the FD group and 95% in surgical group (p < 0.0001). The rate of complete occlusion at 12 months was 65% in the FD group and 97.5% in surgical group. The difference between groups was still significant (p = 0.001). There were no significant differences between groups by occurrence of ischemic (p = 0.108) and hemorrhagic (p = 0.615) complications.

CONCLUSION

The study demonstrated superior clinical outcomes for endovascular flow diversion in comparison with bypass surgery in treatment of complex aneurysms. Though, both techniques grant similar percentage of major neurologic complications and comparable cure rate for cranial neuropathy. Nevertheless, flow diversion is associated with significantly lower early obliteration rate, thus possesses patient for risks of prolonged dual antiplatelet regimen and delayed rupture. Hence, it's important to stratify patient by the natural risk of aneurysm rupture prior to treatment selection.

Treatment of Small and Tiny Aneurysms Before and After Flow Diversion Era: A Single Center Experience of 409 Aneurysms

OBJECTIVE

To explore whether we should use the Pipeline embolization device (PED) as the primary treatment modality for small and tiny aneurysms at anterior circulation.

METHODS

This retrospective study included 409 cases of small and tiny aneurysms, including aneurysms treated by the PED (n = 77), coiling (n = 51), and stent-assisted coiling (SAC) (n = 281). We also made a comparison regarding the safety and efficacy among these treatment modalities.

RESULTS

A total of 55 patients with 77 small aneurysms were treated with PEDs. Technical success was achieved in 98.4% of procedures. The complete occlusion rate was 75.9% (44/58). Both the morbidity and mortality rates were 1.8%. Comparing the 3 treatment modalities, the technical event rate tended to be the highest in the PED group (4.8% vs. 2.0% and 1.1%; PED vs. Coil vs. SAC; P = 0.100), and the use of a PED neither significantly shortened the procedure duration (127.2 ± 62.8 vs. 115 ± 37.1 and 112.8 ± 40.6 minutes, P = 0.322) nor lowered the complication rate (11.1% vs. 9.8% and 6.1%; P = 0.281). SAC had the highest occlusion rate (75.9% vs. 75.8% and 94.0%; P < 0.001) and lowest morbidity rate (0.8% vs. 4.2% and 1.8%; SAC vs. Coil vs. PED; P = 0.099). Ipsilateral multiple aneurysms were more frequently seen in the PED group (33.8% vs. 3.9% and 3.2%; P < 0.001). Procedure duration tended to be lower in the PED group versus the SAC group (122.7 ± 57.4 vs. 157.5 ± 22.2 minutes; P = 0.060). For these aneurysms, the PED group had the highest occlusion rate (80.0% vs. 50.0% and 66.7%; P = 0.516).

CONCLUSIONS

The PED is an alternative treatment for small and tiny aneurysms. However, SAC remains the safest and most efficient treatment modality. The PED should be reserved for ipsilateral multiple aneurysms.

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.

Treatment of Intracranial Aneurysms with the Pipeline Embolization Device Only: a Single Center Experience

Purpose

The aim of this study was to evaluate the technical feasibility and rate of mid-term occlusion in aneurysms treated solely with the Pipeline Embolization Device (PED) in a German tertiary care university hospital.

Materials and Methods

Forty-nine non-consecutive intracranial aneurysms underwent endovascular treatment using the PED exclusively between March 2011 and May 2017 at our institution. Primary endpoint was a favorable aneurysm occlusion defined as OKM C1-3 and D (O'Kelly Marotta Scale). Secondary endpoints were retreatment rate and delayed complications. Median follow-up was 200 days.

Results

The mean aneurysm size was 7.1 ± 5.3 mm. Forty-four aneurysms were located in the anterior circulation (90%). Ten aneurysms were ruptured (20%). Branching vessels from the sac were observed in 11 aneurysms (22%). Favorable obliteration immediately after PED placement was seen in 13/49 aneurysms (27%), of those nine aneurysms were completely occluded (18%). Angiographic and clinical follow-up was available for 45 cases (92%); 36/45 aneurysms (80%) were occluded completely and 40/45 aneurysms (89%) showed a favorable occlusion result. A branching vessel arising from the aneurysm sac was associated with incomplete occlusion (P < .05). All electively treated patients had good outcome (mRS 0). Three aneurysms (6%) required additional treatment due to aneurysm recurrence.

Conclusion

In our series, treatment of intracranial aneurysms with the PED was associated with favorable occlusion rates and low complication rates at mid-term follow-up. The presence of branching vessels arising from the aneurysms sac was predictive for an incomplete occlusion.

Flow diversion in the treatment of aneurysms: a randomized care trial and registry

OBJECTIVE

The Flow Diversion in the Treatment of Intracranial Aneurysm Trial (FIAT) was designed to guide the clinical use of flow diversion, an innovative method to treat intracranial aneurysms, within a care trial and to study safety and efficacy.

METHODS

FIAT, conducted in 3 Canadian hospitals, proposed randomized allocation to flow diversion or standard management options (observation, coil embolization, parent vessel occlusion, or clip placement), and a registry of non-randomized patients treated with flow diversion. The primary safety outcome was death or dependency (modified Rankin Scale score > 2) at 3 months, to be determined for all patients who received flow diversion at any time. The primary efficacy outcome was angiographic occlusion at 3–12 months combined with an independent clinical outcome.

RESULTS

Of 112 participating patients recruited between May 2, 2011, and February 25, 2015, 78 were randomized (39 in each arm), and 34 received flow diversion within the registry. The study was halted due to safety concerns. Twelve (16%) of 75 patients (95% CI 8.9%–26.7%) who were allocated to or received flow diversion at any time were dead (n = 8) or dependent (n = 4) at 3 months or more, crossing a predefined safety boundary. Death or dependency occurred in 5 (13.2%) of 38 patients randomly allocated and treated by flow diversion (95% CI 5.0%–28.9%) and in 5 (12.8%) of 39 patients allocated to standard treatment (95% CI 4.8%–28.2%). Efficacy was below expectations of the trial hypothesis: 16 (42.1%) of 38 patients (95% CI 26.7%–59.1%) randomly allocated to flow diversion failed to reach the primary outcome, as compared with 14 (35.9%) of 39 patients allocated to standard treatment (95% CI 21.7%–52.9%).

CONCLUSIONS

Flow diversion was not as safe and effective as hypothesized. More randomized trials are needed to determine the role of flow diversion in the management of aneurysms.

Clinical trial registration no.: NCT01349582 (clinicaltrials.gov)

Analysis of Predictors and Probability of Aneurysm Occlusion in the Internal Carotid Artery After Treatment with Pipeline Embolization Device

BACKGROUND

Although the Pipeline Embolization Device (PED) has proved to be an excellent option for internal carotid artery (ICA) aneurysms, the rate of occlusion remains difficult to predict and factors associated with aneurysm occlusion are not well elucidated. This study aimed to investigate predictors and the rate of occlusion for aneurysms along the ICA.

METHODS

A total of 117 saccular ICA aneurysms treated with the PED were studied. Occlusion rates were divided among 4 groups: group A [lesions >10 mm in the proximal ICA (petrous to the superior hypophyseal segments)]; group B (lesions <10 mm in the proximal ICA); group C [lesions >10mm in the distal ICA (posterior communicating segment to the ICA bifurcation)]; and group D (lesions <10 mm in the distal ICA). Predictors of aneurysm occlusion were entered into a multivariate Cox regression analysis.

RESULTS

The median time to aneurysm occlusion was 8 months in group A (95% confidence interval [CI], 7.0-9.1), 5.2 months in group B (95% CI, 4.5-6.0), 6.9 months in group C (95% CI, 6.5-7.2), and 10.2 months in group D (95% CI, 6.9-13.6) (P = 0.045). There was a statistically significant difference between the probability of aneurysm occlusion in group B compared with distal ICA aneurysms (P = 0.02). Small proximal ICA aneurysms were more likely to occlude over time compared with other aneurysm groups (hazard ratio, 1.76; 95% CI, 1.07-2.9; P = 0.02).

CONCLUSIONS

The rate of occlusion after PED is highest for small proximal ICA aneurysms and the probability of occlusion is lower for distal ICA aneurysms.