Endovascular Embolization of Intracranial Aneurysms Using Bare Platinum Axium™ Detachable Coils: Immediate and Short-Term Follow-up Results from a Multicenter Registry

Outcomes Associated With Intracranial Aneurysm Treatments Reported as Safe, Effective, or Durable: A Systematic Review and Meta-Analysis

Importance

Testing new medical devices or procedures in terms of safety, effectiveness, and durability should follow the strictest methodological rigor before implementation.

Objectives

To review and analyze studies investigating devices and procedures used in intracranial aneurysm (IA) treatment for methods and completeness of reporting and to compare the results of studies with positive, uncertain, and negative conclusions.

Data Sources

Embase, MEDLINE, Web of Science, and The Cochrane Central Register of Clinical Trials were searched for studies on IA treatment published between January 1, 1995, and the October 1, 2022. Grey literature was retrieved from Google Scholar.

Study Selection

All studies making any kind of claims of safety, effectiveness, or durability in the field of IA treatment were included.

Data Extraction and Synthesis

Using a predefined data dictionary and analysis plan, variables ranging from patient and aneurysm characteristics to the results of treatment were extracted, as were details pertaining to study methods and completeness of reporting. Extraction was performed by 10 independent reviewers. A blinded academic neuro-linguist without involvement in IA research evaluated the conclusion of each study as either positive, uncertain, or negative. The study followed Preferring Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Main Outcomes and Measures

The incidence of domain-specific outcomes between studies with positive, uncertain, or negative conclusions regarding safety, effectiveness, or durability were compared. The number of studies that provided a definition of safety, effectiveness, or durability and the incidence of incomplete reporting of domain-specific outcomes were evaluated.

Results

Overall, 12 954 studies were screened, and 1356 studies were included, comprising a total of 410 993 treated patients. There was no difference in the proportion of patients with poor outcome or in-hospital mortality between studies claiming a technique was safe, uncertain, or not safe. Similarly, there was no difference in the proportion of IAs completely occluded at last follow-up between studies claiming a technique was effective, uncertain, or noneffective. Less than 2% of studies provided any definition of safety, effectiveness, or durability, and only 1 of the 1356 studies provided a threshold under which the technique would be considered unsafe. Incomplete reporting was found in 546 reports (40%).

Conclusions and Relevance

In this systematic review and meta-analysis of IA treatment literature, studies claiming safety, effectiveness, or durability of IA treatment had methodological flaws and incomplete reporting of relevant outcomes supporting these claims.

Avenir® vs. AxiumTM Coils for the Treatment of Intracranial Aneurysms: Results of a Multicenter Randomized Controlled Trial With Short-Term Follow-Up

Purpose

Endovascular coil occlusion is a successful and rapidly evolving strategy used to treat patients who present with intracranial aneurysms. This study aimed to compare the safety and efficacy of the Avenir® and Axium^TM passive mechanically detachable coil systems.

Methods

A prospective, multicenter, randomized controlled study was carried out at ten medical centers from March 2018 to December 2019. A series of consecutive patients diagnosed with intracranial aneurysms were randomly assigned to undergo endovascular treatment with either the Avenir® or the Axium^TM mechanically detachable coil systems. The short-term outcomes from the two groups were compared with a focus on treatment efficacy and safety.

Results

A total of 162 and 161 patients were enrolled in the Avenir and Axium groups, respectively. The rate of successful coil detachment was 100% for the Avenir group and 99.38% for the Axium group. At the six-month follow-up visit, the overall aneurysm occlusion rate was 94.66% for the Avenir group and 96.95% for the Axium group (p > 0.05). We observed no statistically significant differences in clinical condition (as per the modified Rankin Scale) or the degree of aneurysm occlusion (as determined by digital subtraction angiography [DSA] and Raymond-Roy Occlusion Classification). Surgical complications were reported in 27 subjects in the Avenir group and 22 in the Axium group (p > 0.05). DSA performed at 6 months revealed complete aneurysm occlusion in 84 and 86% of patients in the Avenir and Axium groups, respectively.

Conclusion

We observed no significant short-term differences with respect to efficacy or safety when using either Avenir® or Axium^TM coils for the treatment of intracranial 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.

Angiographic and clinical results of anterior communicating artery aneurysm endovascular treatment

Introduction

The anterior communicating artery (ACoA) is the most common location of intracranial aneurysms, observed in 35% of cases. Endovascular treatment has become an alternative to surgical clipping and the primary method of choice.

Aim

To assess the treatment results of ruptured and unruptured ACoA aneurysms and to assess the incidence of intraprocedural complications and various factors influencing these aspects.

Material and methods

One hundred and eleven embolizations of ACoA aneurysms (80.7% ruptured and 19.3% unruptured) were retrospectively analysed. The methods of embolization were: coiling, balloon-assisted coiling, stent-assisted coiling. Morphology and dimensions of aneurysms were assessed on 3D digital subtraction angiography (DSA) images. Medical records were analysed for patient’s clinical status at admission, intraprocedural complications, follow-up examination and modified Rankin Scale (mRS) score 1 month after discharge.

Results

Immediately after the procedure 56.9% of patients had Raymond-Roy Occlusion Classification (RROC) class I, 37.6% class II and 5.5% class III. The overall intraprocedural complication rate was 6.6%. There were significantly more cases of bleeding (p = 0.012) and coil prolapse (p = 0.012) during the procedures ending with higher packing density. Twenty-eight (25.7%) patients died during hospital stay, 27 (96.4%) with ruptured aneurysm. In the follow-up of 41 patients, RROC was the same or improved in 73.2% of cases and recanalization occurred in 26.8%. Six patients with aneurysm recanalization underwent repeat embolization.

Conclusions

Endovascular embolization of ACoA aneurysms is an effective and safe treatment method. The most powerful factor influencing the incidence of complications is packing density. Superior orientation of the dome, initial incomplete embolization and poor outcome in mRS scale are factors predisposing to ACoA aneurysm recurrence.

Experimental study of the characteristics of various types of filling coils for intracranial aneurysm embolisation

Background In endovascular embolisation for an intracranial aneurysm, after framing coil deployment, soft coils (often called filling coils) are usually selected to fill inside the cage of previous coils. Various kinds of filling coils are available, although each coil has its own characteristics. Understanding their differences to ensure proper coil selection is important to achieve successful embolisation. The purpose of this study was to investigate the characteristics of various filling coils. Materials and methods The authors developed a radiolucent coil to evaluate the performance of coils under conditions simulating the course of embolisation. Experimental embolisation was performed by using a silicone aneurysm filled with radiolucent coils. Indices including area, circularity, centroid position and coefficient of variation were investigated by analysing the figures of the filling coils after being inserted into the radiolucent coil under fluoroscopy. Results The characteristics of each coil depended on the coil design. The helical coil had the highest circularity and centroid position scores and lowest area score. Therefore, it tended to develop a compacted mass. The low shape-memory coil had the lowest circularity, second-highest centroid position and highest coefficient of variation scores. Therefore, it tended to develop irregularly shaped distribution with low reproducibility. Complex coils generally had higher area and circularity scores. Therefore, they tended to provide a balanced distribution with relatively expanded mass and less small compartmentation. Conclusions The evaluated characteristics of various filling coils should be useful for appropriate selection of filling coils.

Evaluation of the characteristics of various types of finishing coils for the embolization of intracranial aneurysms in an experimental model with radiolucent coils

In endovascular coil embolization of intracranial aneurysms, very soft coils, often called "finishing coils," are usually selected in the final stage of coil embolization. The authors developed a radiolucent coil made of thin nylon thread to evaluate the performance of coils under a situation simulating the course of embolization. The characteristics of various types of finishing coils were investigated using radiolucent coils. Experimental embolization was performed with a silicone aneurysm filled with radiolucent coils simulating the final stage of embolization. Three indices, i.e. area, perimeter, and circularity of the inserted coils, were investigated on the X-ray images after coil insertion. The coils used were as follows: Target Ultra Helical, MicroPlex Hypersoft, Axium Helix, ED Coil Extrasoft, and DeltaPlush. In the analysis of area and perimeter, there were significant differences in multiple comparisons. There was no significant difference in circularity, although it was generally ranked in order by coil brand. Target Ultra and MicroPlex Hypersoft had higher scores for area and perimeter and lower scores for circularity, in contrast to DeltaPlush, which had lower scores for area and perimeter and a higher score for circularity. Based on these results, the finishing coils were divided into three groups: Target Ultra Helical and MicroPlex Hypersoft; Axium Helix and ED Coil Extrasoft; DeltaPlush. They are better for use in early, midst, and end of finishing, respectively. The characteristics of various finishing coils were evaluated, and the results obtained reflected actual clinical experience and provide useful information to appropriately select finishing coils.

Polymeric embolization coil of bilayered polyvinyl alcohol strand for therapeutic vascular occlusion: a feasibility study in canine experimental vascular models

PURPOSE

To investigate the feasibility of polyvinyl alcohol (PVA) polymer coil as a new endovascular embolic agent and to gauge the related histologic response in a canine vascular model.

MATERIALS AND METHODS

PVA polymer coil was fabricated by cross-linking PVA and tantalum particles. Basic properties were then studied in vitro via swelling ratio and bending diameter. Normal renal segmental arteries and wide-necked aneurysms of carotid sidewalls served as canine vascular models. Endovascular PVA coil embolization of normal renal segmental arteries (N = 20) and carotid aneurysms (N = 8) was performed under fluoroscopic guidance in 10 dogs. Degree of occlusion was assessed immediately and at 4 weeks after embolization by conventional and computed tomographic angiography. Histologic features were also graded at acute (day 1, six segmental arteries and four aneurysms) and chronic phases (week 4, 14 segmental arteries and four aneurysms) after embolization to assess inflammation, organization of thrombus, and neointimal proliferation.

RESULTS

Swelling ratio declined as concentrations of cross-linking agent increased. Mean bending diameters were 2.05 mm (range, 0.86-6.25 mm) in water at 37 °C and 2.29 mm (range, 0.94-6.38 mm) in canine blood samples at 37 °C. Occlusion of normal renal segmental arteries was sustained (complete occlusion at day 1, n = 20; at week 4, n = 14), whereas immediate outcomes in carotid aneurysms (day 1, complete occlusion, n = 5; residual neck only, n = 3) were not sustained (week 4, complete occlusion, n = 1; minor recanalization, n = 1; major recanalization, n = 2). At week 4, chronic inflammatory cells predominated, with progressive organization of thrombus and fibrocellular ingrowth. All aneurysms bore full neointimal linings on the coil mass in the chronic phase.

CONCLUSIONS

Vascular occlusion by PVA polymer coil proved superior in normal renal segmental arteries and feasible in surgically constructed carotid aneurysms (with packing densities ≥ 30%), constituting acceptable radiologic feasibility and histologic response.

Prediction of shape diameter undergoing coil embolization of saccular intracranial aneurysm treatment using a hybrid decision support system

The purpose of the study was to design a hybrid decision support system (HDSS) that could simulate the embolized coil selection pattern of the radiologists in aneurysms treatment. As the longest available length of the coils should be used in most cases, therefore only the shape diameter (SD) selection was modeled and varied. Ninety-eight aneurysms successfully treated by a radiologist with coil embolization were divided into two groups (86 for training and 12 randomly selected for validating). Eight aneurysms treated by another radiologist were also used to cross validate the proposed HDSS. The HDSS was developed using the classification and the linear regression methods (LRM). The dome and the width of an aneurysm were used as the system inputs. The system outputs were the SDs of the first three coils indexed according to the insertion order. The HDSS that consisted of Bagging classification and LRM achieved the highest accuracy for all cases. The errors were within 1 mm for the SD selection of the first two coils. For the third coil, the SD selection within 1 mm bound had 80 % accuracy. The experimental results indicated the feasibility of using the HDSS as the guidance for selecting the SDs of the first two coils. The selection of the third coil required more training data for the rarely used SD. Moreover, the cross validation with another radiologist showed the feasibility of using the proposed HDSS as the guidance, however further validation with more data is recommended.