Comparison of coil types in aneurysm recurrence

A comparison of endovascular coil systems for the treatment of small intracranial aneurysms

BACKGROUND

Endovascular coiling of small, intracranial aneurysms remains controversial and difficult, despite advances in technology.

METHODS

We retrospectively reviewed data for 62 small aneurysms (<3.99 mm) in 59 patients. Occlusion rates, complications rates, and coil packing densities were compared between subgroups based upon coil type and rupture status.

RESULTS

Ruptured aneurysms predominated (67.7%). Aneurysms measured 2.99 ± 0.63 mm by 2.51 ± 0.61 mm with an aspect ratio of 1.21 ± 0.34 mm. Brands included Optima (Balt) (29%), MicroVention Hydrogel (24.2%), and Penumbra SMART (19.4%) coil systems. Average packing density was 34.3 ± 13.5 mm³. Occlusion rate was 100% in unruptured aneurysms; 84% utilized adjuvant devices. For ruptured aneurysms, complete occlusion or stable neck remnant was achieved in 88.6% while recanalization occurred in 11.4%. No rebleeding occurred. Average packing density (p = 0.919) and coil type (p = 0.056) did not impact occlusion. Aspect ratio was smaller in aneurysms with technical complications (p = 0.281), and aneurysm volume was significantly smaller in those with coil protrusion (p = 0.018). Complication rates did not differ between ruptured and unruptured aneurysms (22.6 vs. 15.8%, p = 0.308) or coil types (p = 0.830).

CONCLUSION

Despite advances in embolization devices, coiling of small intracranial aneurysms is still scrutinized. High occlusion rates are achievable, especially in unruptured aneurysms, with coil type and packing density suggesting association with complete occlusion. Technical complications may be influenced by aneurysm geometry. Advances in endovascular technologies have revolutionized small aneurysm treatment, with this series demonstrating excellent aneurysm occlusion especially in unruptured aneurysms.

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.

Clinical outcomes of first- and second-generation hydrogel coils compared with bare platinum coils: a systematic literature review

Endovascular coiling has revolutionized intracranial aneurysm treatment; however, recurrence continues to represent a major limitation. The hydrogel coil was developed to increase packing density and improve neck healing and therefore decrease recurrence rates. In this paper, we review treatment outcomes of first- (1HCs) and second-generation (2HCs) hydrogel coils and compare them to those of bare platinum coils (BPC). A query of multiple databases was performed. Articles with at least 10 aneurysms treated with either 1HC or 2HC were selected for analysis. Collected data included aneurysm size, rupture status, initial occlusion, initial residual neck/aneurysm, packing density, mortality, morbidity, recurrence, and retreatment rates. The primary endpoint was recurrence at final follow-up. Secondary endpoints included residual neck and dome rates as well as procedure-related complications and functional dependence at final follow-up. Studies that compared 1HC to BPC showed significant lower recurrence (24% vs. 30.8%, p = 0.02) and higher packing density (58.5% vs. 24.1%, p < 0.001) in 1HC but no significant difference in initial occlusion rate (p = 0.08). Studies that compared 2HC to BPC showed lower recurrence (6.3% vs. 14.3%, p = 0.007) and retreatment rates (3.4% vs. 7.7%, p = 0.010) as well as higher packing density (36.4% vs. 29.2%, p = 0.002) in 2HC, with similar initial occlusion rate (p = 0.86). The rate of complications was not statistically different between HC (25.5%) and BPC (22.6%, p = 0.06). Based on our review, the 1HC and 2HC achieved higher packing density and lower recurrence rates compared to BPC. The safety profile was similar between both groups.

Autologous adipose-derived mesenchymal stem cells improve healing of coiled experimental saccular aneurysms: an angiographic and histopathological study

PURPOSE

Long-term occlusion of coiled aneurysms frequently fails, probably because of poor intrasaccular healing and inadequate endothelialization across the aneurysm neck. The purpose of this study was to determine if attachment of autologous mesenchymal stem cells (MSCs) to platinum coils would improve the healing response in an elastase-induced aneurysm model in rabbits.

MATERIALS AND METHODS

With approval from the institutional animal care and use committee, aneurysms were created in rabbits and embolized with control platinum coils (Axium; Medtronic) (n=6) or coils seeded ex vivo with autologous adipose-tissue MSCs (n=7). Aneurysmal occlusion after embolization was evaluated at 1 month with angiography. Histological samples were analyzed by gross imaging and graded on the basis of neck and dome healing on H&E staining. Fibrosis was evaluated using a ratio of the total area presenting collagen. Endothelialization of the neck was quantitatively analyzed using CD31 immunohistochemistry. χ² and Student's t-test were used to compare groups.

RESULTS

Healing score (11.5 vs 8.0, p=0.019), fibrosis ratio (10.3 vs 0.13, p=0.006) and endothelialization (902 262 μm² vs 31 810 μm², p=0.041) were significantly greater in the MSC group. The MSC group showed marked cellular proliferation and thrombus organization, with a continuous membrane bridging the neck of the aneurysm. Angiographic stable or progressive occlusion rate was significantly lower in the MSC group (0.00, 95% CI 0.00 to 0.41) compared with controls (0.67, 95% CI 0.22 to 0.96) (p=0.02).

CONCLUSIONS

Autologous MSCs attached to platinum coils significantly improve histological healing, as they result in improved neck endothelialization and collagen matrix formation within the aneurysm sac.

Mesenchymal stem cells and endothelial progenitor cells accelerate intra-aneurysmal tissue organization after treatment with SDF-1α-coated coils

Recurrences of aneurysms remain the major drawback of detachable coils for the endovascular treatment of intracranial aneurysms. The aim of the present study is to develop new modified coils, coating the surface of platinum coils with silk fibroin (SF) consisting of stromal cell-derived factor-1α (SDF-1α), and evaluate its acceleration of organization of cavities and reduction of lumen size in a rat aneurysm model. The morphological characteristics of SDF-1α-coated coils were examined using scanning electron microscopy (SEM). Fifty experimental aneurysms were created and randomly divided into five groups: three groups were embolized with SDF-1α-coated coils (8 mm) and two of these groups need transplantation of mesenchymal stem cells (MSCs) or endothelial progenitor cells (EPCs); one group was embolized with bare coils (8 mm) and another group severed as control. After coil implantation for 14 or 28 days, the coils were harvested and histological analysis was performed. SEM photographs showed that SF/SDF-1α-coated coils have uniform size and a thin film compared with bare coils. In the group treated with SDF-1α-coated coils, tissue organization was accelerated and the proliferation of α-smooth muscle actin positive cells was promoted in the aneurysmal sac. Compared with unmodified coils, on day 28, tissue organization was significantly greater in the group treated with SDF-1α-coated coils and MSC or EPC transplantation. These results suggest that SDF-1α-coated coils with MSC or EPC transplantation may be beneficial in the aneurysm healing and endothelialization at the orifice of embolized aneurysm.

Safety and effectiveness of large volume coils in the treatment of small aneurysms

BACKGROUND AND PURPOSE

Large volume soft design coils facilitate quicker aneurysm filling and high packing density. Our purpose was to analyze the feasibility, safety, and effectiveness of the Penumbra Coil 400 (PC400) system in the treatment of small aneurysms.

MATERIALS AND METHODS

A retrospective analysis of prospective data collected at three different centers was performed on consecutive aneurysms <10 mm treated with the PC400 system. A total of 92 aneurysms were included in the study. Feasibility, procedure safety, angiographic and clinical results, and follow-up results were evaluated.

RESULTS

Mean aneurysm size was 5.8±2.0 mm. An average of 2.5±1.3 coils with a mean length of 18±16 cm per aneurysm was used, resulting in a mean packing density of 45.6±14.4%. The thromboembolic event rate was 3.3% and no procedural aneurysm rupture was observed. Immediate adequate occlusion was achieved in 66% of aneurysms. During a mean follow-up period of 7.4 months the number of adequate occlusions increased to 91%.

CONCLUSIONS

Large volume PC 400 coils are safe and effective in the treatment of small aneurysms with a low thromboembolic complication rate and no hemorrhagic events. High packing densities are achieved with a low average number of coils used per aneurysm treated. The aneurysms demonstrated progressive occlusion over time, which probably suggests stability in the long term.

Follow-up of cerebral aneurysm embolization with hydrogel embolic system: Systematic review and meta-analysis

BACKGROUND

Hydrogel embolic system (HES) for endovascular treatment of cerebral aneurysms was developed to reduce the risk of aneurysm recurrence and the rate of retreatment. The aim of this systematic review was to verify the efficacy of HES, also in comparison to bare platinum coils (BPC).

MATERIAL AND METHODS

A systematic literature search was performed by two independent reviewers for articles published until January 31st, 2013 on the follow-up recurrence rate of intracranial aneurysm embolization with hydrogel-coated coils.

RESULTS

Thirteen articles on the use of HES for embolization of cerebral aneurysms were included in this study, for a total of 1683 embolized aneurysms. Significant heterogeneity was found regarding patient populations, methods of aneurysm coiling, follow-up schedules, and recurrence definitions. The pooled rate of initial complete aneurysm occlusion was 55% (95%CI, 38-70%); 59% (95%CI, 43-74%) in the subgroup of aneurysms treated with the use of HES. The pooled total recurrence rate was 19% (95%CI, 15-24%); 17% (95%CI, 14-22%) in the HES-treated subgroup. The pooled major recurrence rate was 12% (95%CI, 8-18%); 11% (95%CI, 7-16%) in the HES-treated subgroup. Comparing both types of coils, the pooled odds ratio for total recurrence was 0.63 (95%CI, 0.45-0.88; p=0.008) in favor of HES.

CONCLUSIONS

Embolization of cerebral aneurysms using HES seems to result in a lower rate of recurrence than that obtained using BPC, which is in line with the only randomized controlled trial. High-quality prospective studies are needed to define specific indications for the use of hydrogel-coated coils.

Guidelines for the Management of Patients With Unruptured Intracranial Aneurysms: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

PURPOSE

The aim of this updated statement is to provide comprehensive and evidence-based recommendations for management of patients with unruptured intracranial aneurysms.

METHODS

Writing group members used systematic literature reviews from January 1977 up to June 2014. They also reviewed contemporary published evidence-based guidelines, personal files, and published expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulated recommendations using standard American Heart Association criteria. The guideline underwent extensive peer review, including review by the Stroke Council Leadership and Stroke Scientific Statement Oversight Committees, before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee.

RESULTS

Evidence-based guidelines are presented for the care of patients presenting with unruptured intracranial aneurysms. The guidelines address presentation, natural history, epidemiology, risk factors, screening, diagnosis, imaging and outcomes from surgical and endovascular treatment.

Occlusion of canine aneurysms using microporous self-expanding stent grafts: long-term follow-up

PURPOSE

The treatment of large or giant cerebral aneurysms by surgical and/or endovascular techniques is difficult and poses relatively high risks. Therefore, a microporous self-expanding (hybrid) stent graft composed of a thin, expandable, segmented polyurethane (SPU) membrane with micropores and a drug-delivery system was developed.

MATERIALS AND METHODS

A commercially available, self-expanding carotid stent was covered with a thin microporous SPU membrane fabricated by the dip-coating method and the excimer laser ablation technique, with an intraluminal coating of argatroban. Experimentally fabricated lateral-wall aneurysms in canine carotid arteries using venous pouches were occluded with the hybrid stent graft (bale-shaped pore density of 23.6%) on one side and a bare-metal stent on the other side without systemic antiplatelet therapy.

RESULTS

Angiography at 1, 6, and 12 months of stenting revealed that all arteries were patent without marked stenosis without systemic antiplatelet therapy. All aneurysms treated with hybrid stent grafts remained occluded throughout the 12-month period, while among those treated by bare-metal stents, 2 of 3 aneurysms were occluded at 6 months (67%) and only 1 of 3 aneurysms were occluded at 12 months (33%). Histology revealed that the novel hybrid stent graft had less intimal hyperplasia than the bare-metal stent. The hybrid stent graft was useful for the successful occlusion of these canine carotid aneurysms, even at 12 months.

CONCLUSIONS

The novel hybrid stent grafts are expected to overcome the disadvantages of fully covered stent grafts and simple bare-metal stents, while combining both their merits, and appear to be useful in the treatment of large or giant cerebral aneurysms.

Use of stent-assisted coil embolization for the treatment of wide-necked aneurysms: A systematic review

Background:

The use of stent-assisted coiling (SAC) has been shown to be a treatment option for complex aneurysms. We reviewed systematically the immediate and mid-term angiographic results following treatment of wide-necked aneurysms with self-expanding stents and coils, as well as the peri- and postprocedural rate of complications.

Methods:

A computerized database search was conducted from 01/2000 to 04/2011 using appropriate indexed terms on Pubmed. Inclusion criteria were: (1) homogeneous populations of ≥10 patients with wide-necked aneurysms; (2) use of a self-expandable neurovascular stent and coils for aneurysm treatment; (3) immediate and follow-up angiographic results; and (4) periprocedural and delayed thrombotic complications.

Results:

Seventeen studies were included, containing retrospectively collected data on 656 patients/702 aneurysms. The target aneurysm was located on the anterior circulation in 78.4% of patients. The immediate rate of complete occlusion was 46.3%, (19.3-98.1%). The intra- and postprocedural rate of intrastent thrombosis or thromboembolic event was 4.6% and 4.3%, respectively. Complete occlusion was documented in 71.9% at last angiographic follow-up. The rate of recanalization was 13.2% of aneurysms (0-28.8%). Delayed in-stent stenosis occurred in 5.3% cases (0-20.6%).

Conclusion:

SAC has been considered a treatment option for selected wide-necked aneurysms in some institutions. The use of intracranial stents should take into consideration the risk of ischemic complications, recanalization, delayed in-stent stenosis; and the currently unknown lifetime risks for stenosis, vascular injury, device failure, and aneurysm recurrence related to intracranial stenting. There is an evident need for a prospective multicenter registry for all treated patients with SAC.