Off-Label Application of Pipeline Embolization Device for Intracranial Aneurysms

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.

Safety and efficacy profile of off-label use of the Pipeline Embolization Device: A systematic review and meta-analysis

OBJECTIVE

The off-label utilization of the Pipeline Embolization Device (PED) is a common practice in numerous medical centers globally. Therefore, we conducted a systematic review and meta-analysis to evaluate the overall outcomes of this off-label usage of PEDs.

METHODS

PubMed, Web of Science, Ovid Medline, Ovid Embase, and Scopus were searched up to February 2023 using the Nested Knowledge platform to identify studies assessing the off-label use of PEDs. Any use of PED outside of the FDA-approved indication granted in 2018 is considered off-label use. Overall angiographic occlusion rates, ischemic and hemorrhagic complications, mortality, retreatment rates, and favorable clinic outcomes were included. Statistical analyses were performed to compare the overall outcome rates of anterior cerebral artery(ACA) vs. middle cerebral artery(MCA) and anterior vs posterior circulation subgroups.

RESULTS

We included 26 studies involving a total of 1,408 patients. The overall rate of complete occlusion was 80.3 % (95 % CI= 76.0-84.1). Subgroup analysis demonstrated a statistically significant difference in the rate of complete occlusion between anterior circulation (78.9 %) and posterior circulation (69.2 %) (p value=0.02). The rate of good clinical outcomes was 92.8 % (95 % CI= 88.8-95.4). The mortality rate was 1.4 % (95 % CI= 0.5-2.7). The overall rate of ischemic complications was 9.5 % (95 % CI= 7.7-11.6), with a comparable difference between anterior circulation (7.7 %) and posterior circulation (12.8 %) (p value=0.07). There was no statistically significant difference in MCA vs ACA subgroups in all parameters.

CONCLUSIONS

Off-label use of PEDs can be a safe and effective treatment option for intracranial aneurysms. However, there is a need for more prospective, high-quality, non-industry-funded registry studies and randomized trials to test the efficacy and safety of off-label usage of PEDs and to expand its indications.

Predictors of aneurysmal occlusion following intracranial aneurysms treatment with pipeline embolization device

PURPOSE

Pipeline embolization device (PED) is thought to induce aneurysmal occlusion through diversion of flow away from the aneurysmal sac with subsequent thrombosis and endothelialization. The impact of different factors especially hypertension (HTN)-a known predisposing factor to hypercoagulability and altered endothelial function-on aneurysmal occlusion after flow diversion has not been studied. We sought to determine predictors of aneurysmal occlusion following PED treatment focusing on impact of blood pressure.

METHODS

Database of patients with cerebral aneurysms treated with PED from 2013 to 2019 at our institution was retrospectively reviewed. Patients were defined as hypertensive if (1) they had a documented history of HTN requiring anti-HTN medications or (2) average systolic blood pressure on three measurements was > 130 mmHg. The primary outcome was aneurysm occlusion status at the last imaging follow-up. Multivariable logistic regression model was constructed to assess the effect of HTN on occlusion, controlling for age, smoking, aneurysmal size, fusiform morphology, posterior circulation location, and incorporated branches.

RESULTS

A total of 331 aneurysms in 294 patients were identified for this analysis. The mean age was 59 years (79.9% female). Fifty-five percent of the cohort were classified as hypertensive. When controlling for other potential confounders, hypertensive patients trended toward higher odds of achieving complete occlusion compared to non-hypertensive patients (OR = 2.05; 95% CI = 0.99-4.25; p = 0.052). Meanwhile, age (OR = 0.91; 95% CI = 0.88-0.95; p < 0.001) and an incorporated branch into an aneurysm (OR = 0.22; 95% CI = 0.08-0.58; p < 0.002) were associated with decreased odds for complete aneurysmal occlusion.

CONCLUSION

Hypertensive patients show a trend toward higher odds of achieving complete occlusion when controlling for potential confounders. The HTN-induced hypercoagulable state, enhanced endothelial activation, and altered extracellular matrix regulation might be the contributing factors. Further research is warranted to explore clinical implications of these findings.

Long-term outcomes following pipeline embolization of unruptured aneurysms

BACKGROUND

Flow diversion using the pipeline embolization device (PED) for unruptured aneurysms is associated with high occlusion and low morbidity and mortality. However, most reports have limited follow-up of 1-2 years. Therefore, we sought to report our outcomes after PED for unruptured aneurysms in patients with at least 5-years of follow-up.

METHODS

Review of patients undergoing PED for unruptured aneurysms from 2009 to 2016.

RESULTS

Overall, 135 patients with 138 aneurysms were included for analysis. Seventy-eight percent of aneurysms (n=107) over a median radiographic follow-up of 5.0 years underwent complete occlusion. Among aneurysms with at least 5-years of radiographic follow-up (n=71), 79% (n=56) achieved complete obliteration. No aneurysm recanalized after radiographic obliteration. Furthermore, over a median clinical follow-up period of 4.9 years, 84% of patients (n=115) self-reported mRS scores between 0 and 2. For patients with at least 5-years of clinical follow-up, 88% (n=61) reported mRS between 0 and 2. In total, 3% (n=4) of patients experienced a major, non-fatal neurologic complication related to the PED, 5% (n=7) of patients experienced a minor neurologic complication related to PED placement, and 2% (n=3) died from either delayed aneurysm rupture, delayed ipsilateral hemorrhage after PED placement, or delayed (9 months after treatment) neural compression after progressive thrombosis of a PED-treated dolichoectactic vertebrobasilar aneurysm.

CONCLUSIONS

Treatment of unruptured aneurysms with the PED is associated with high rates of long-term angiographic occlusion and low, albeit clinically important, rates of major neurologic morbidity and mortality. Thus, flow diversion via PED placement is safe, effective, and durable.

Safety and Efficacy of the Off-Label Use of Pipeline Embolization Device Based on the 2018 Food and Drug Administration-Approved Indications for Intracranial Aneurysms: A Single-Center Retrospective Cohort Study

BACKGROUND

The pipeline embolization device (PED; ev3/Covidien) has proven safe and effective for treating selected intracranial aneurysms. This device's versatility and popularity have driven increased interest in expanding the latest 2018 Food and Drug Administration-approved indications.

OBJECTIVE

To compare "off-label" and "on-label" PED treatment.

METHODS

Retrospective analysis of aneurysms treated with PED at a single center from 2013 to 2019. Comparisons were made based on the 2018 Food and Drug Administration-approved indications.

RESULTS

A total of 492 treated aneurysms were included (65.2% on-label and 34.8% off-label). Aneurysm complete and near-complete occlusion rate was nonsignificantly lower in the off-label group (80.9% vs 85.7%; P = .19). Off-label treatment had higher rate of poor functional outcomes (modified Rankin Scale [mRS] >2: 10.3% vs 3.5%; P = .002). Although pretreatment mRS was already higher in the off-label group (5.3% vs 0.3%; P < .001) and there were no differences in mRS worsening during follow-up (5.5% vs 2.9%; P = .15). We also found a trend to a higher rate of intracranial hemorrhagic complications in the off-label group (4.7% vs 1.6%; P = .05), but there were no differences in hemorrhages requiring surgical intervention (1.8% vs 1.3%; P = .65). There were no differences in retreatment, thromboembolic complications, and mortality rates.

CONCLUSION

Off-label PED treatment may be considered for select aneurysms, which are challenging to treat with other techniques. These cases have similar complete and near-complete occlusion rates compared with on-label cases. There are, however, higher risks of poor functional outcomes despite similar rates of thromboembolic and hemorrhagic complications. This is partly explained by the significantly higher pretreatment mRS score in the off-label group.

Rare Neurovascular Diseases in Korea: Classification and Related Genetic Variants

Rare neurovascular diseases (RNVDs) have not been well-recognized in Korea. They involve the central nervous system and greatly affect the patients' lives. However, these diseases are difficult to diagnose and treat due to their rarity and incurability. We established a list of RNVDs by referring to the previous literature and databases worldwide to better understand the diseases and their current management status. We categorized 68 RNVDs based on their pathophysiology and clinical manifestations and estimated the prevalence of each disease in Korea. Recent advances in genetic, molecular, and developmental research have enabled further understanding of these RNVDs. Herein, we review each disease, while considering its classification based on updated pathologic mechanisms, and discuss the management status of RNVD in Korea.

Endovascular Management of Distal Anterior Cerebral Artery Aneurysms: A Multicenter Retrospective Review

INTRODUCTION

Distal anterior cerebral artery aneurysms (DACAA) are a rare and difficult entity to manage. Endovascular treatment has evolved for safe and durable treatment of these lesions. The objective of this study is to report the safety, efficacy, and outcomes of endovascular treatment of DACAA.

METHODS

A retrospective review of DACAA endovascularly treated at 5 different institutions was performed. Data included demographics, rupture status, radiographic features, endovascular technique, complication rates, and long-term angiographic and clinical outcomes. A primary endpoint was a good clinical outcome (modified Rankin scale 0-2). Secondary endpoints included complications and radiographic occlusion at follow-up.

RESULTS

A total of 84 patients were reviewed. The mean age was 56, and 64 (71.4%) were female. Fifty-two (61.9%) aneurysms were ruptured. A good functional outcome was achieved in 59 patients (85.5%). Sixty (71.4%) aneurysms were treated with primary coiling, and the remaining 24 were treated with flow diversion. Adequate occlusion was achieved in 41 (95.3%) aneurysms treated with coiling, and 17 (89.5%) with flow diversion. There were total 11 (13%) complications. In the flow diversion category, there were 2, both related to femoral access. In the coiling category, there were 9: 5 thromboembolic, 3 ruptures, and 1 related to femoral access.

CONCLUSION

Endovascular treatment, and in particular, flow diversion for DACAA, is safe, feasible, and associated with good long-term angiographic and clinical outcomes.

Neck Location on the Outer Convexity is a Predictor of Incomplete Occlusion in Treatment with the Pipeline Embolization Device: Clinical and Angiographic Outcomes

BACKGROUND AND PURPOSE

With the increasing use of the Pipeline Embolization Device for the treatment of aneurysms, predictors of clinical and angiographic outcomes are needed. This study aimed to identify predictors of incomplete occlusion at last angiographic follow-up.

MATERIALS AND METHODS

In our retrospective, single-center cohort study, 105 ICA aneurysms in 89 subjects were treated with Pipeline Embolization Devices. Patients were followed per standardized protocol. Clinical and angiographic outcomes were analyzed. We introduced a new morphologic classification based on the included angle of the parent artery against the neck location: outer convexity type (included angle,  <160°), inner convexity type (included angle,  >200°), and lateral wall type (160° ≤ included angle  ≤200°). This classification reflects the metal coverage rate and flow dynamics.

RESULTS

Imaging data were acquired in 95.3% of aneurysms persistent at 6 months. Complete occlusion was achieved in 70.5%, and incomplete occlusion, in 29.5% at last follow-up. Multivariable regression analysis revealed that 60 years of age or older (OR, 5.70; P = .001), aneurysms with the branching artery from the dome (OR, 10.56; P = .002), fusiform aneurysms (OR, 10.2; P = .009), and outer convexity-type saccular aneurysms (versus inner convexity type: OR, 30.3; P < .001; versus lateral wall type: OR, 9.71; P = .001) were independently associated with a higher rate of incomplete occlusion at the last follow-up. No permanent neurologic deficits or rupture were observed in the follow-up period.

CONCLUSIONS

The aneurysm neck located on the outer convexity is a new, incomplete occlusion predictor, joining older age, fusiform aneurysms, and aneurysms with the branching artery from the dome. No permanent neurologic deficits or rupture was observed in the follow-up, even with incomplete occlusion.

Single-Center Experience With the Bare p48MW Low-Profile Flow Diverter and Its Hydrophilically Covered Version for Treatment of Bifurcation Aneurysms in Distal Segments of the Anterior and Posterior Circulation

Background and Purpose: Flow diversion has profoundly changed the way aneurysms are treated. However, it conventionally requires dual antiplatelet medication and has yet been considered off-label use in the posterior circulation or within peripheral vessels of the anterior circulation. Here, we report our experience with the p48MW/p48MW hydrophilic coating (HPC) in the anterior and posterior circulation. This novel low-profile flow diverter is specifically designed for treatment of small peripheral vessels, and the p48MW HPC has an anti-thrombotic polymer coating, which allows application of a single antiplatelet function medication in conditions that expectably require further surgery.

Materials and Methods: Thirty-two patients were prospectively included. Twenty-six treatments were performed with one flow diverter, four required two overlapping flow diverters, one case demanded three overlapping flow diverters, and in one case, extensive dissecting aneurysm telescoping with eight flow diverters was necessary. Twenty-two complex bifurcation aneurysms were treated. Three months' follow-up was available for 14 patients.

Results: Deployment was uneventful in all cases. In four cases, undersizing was unavoidable and resulted in significant shortening of the flow diverter, which demanded implantation of further flow diverters to sufficiently treat the target aneurysm. Three flow diverters required balloon angioplasty for optimal wall approximation. All parent vessels remained patent. Available 3-month follow-up studies showed decreased influx or delayed washout in all aneurysms; none was occluded completely. There were no device-related clinical complications.

Conclusions: Implantation of the p48MW/p48MW HPC is safe and effective for treatment of distally located cerebral aneurysms. Considering the reported rates of ischemic complications associated with flow diversion of complex bifurcation aneurysms, the p48MW/p48MW HPC potentially provides increased safety for complex bifurcation aneurysms in the anterior and posterior circulation.