Risk Factors for Recurrence of Intracranial Aneurysm After Coil Embolization: A Meta-Analysis

Risk factors for recanalization after coil embolization for cerebral aneurysms: importance of the first coil and prediction model

BACKGROUND

Endovascular coil embolization for cerebral aneurysms is a well-established treatment; however, postoperative recanalization remains a risk. This study aimed to clarify risk factors for cerebral aneurysm recanalization after coil embolization and to develop a predictive model for assessing risks.

METHODS

This retrospective study included patients with cerebral saccular aneurysms who underwent initial coil embolization at our hospital in Tokyo, Japan between 2012 and 2023. The following cases were excluded: follow-up of <1 year, re-treatment and use of bioactive coils. Outcomes included aneurysm characteristics and postoperative Raymond-Roy Occlusion Classification (RROC). Univariate and multivariate Cox proportional hazards models were used to identify independent predictors. A simplified risk score was constructed using LASSO logistic regression and β-coefficients from multivariable analysis. Internal validity was assessed by bootstrap resampling. External validation was performed using an independent cohort and model performance was evaluated in terms of discrimination and calibration.

RESULTS

Among the 150 patients with aneurysms, 79 were analyzed after applying exclusion criteria. Multivariate analysis identified four independent predictors of recanalization: rupture status, aneurysm size ≥7 mm, RROC without class I, and first volume embolization ratio <8 %. These variables were incorporated into an integer-based risk score ranging from 0 to 7. The model demonstrated strong discrimination in the internal validation cohort (C-statistic: 0.89), which remained acceptable in the external validation cohort (C-statistic: 0.81, 95 % CI: 0.74-0.89). Risk stratification showed increasing recanalization rates of 1.8 %, 13.5 %, and 41.5 % in low- (0-2), intermediate- (3-4), and high-risk (5-7) groups, respectively. Calibration in the external cohort showed slight overestimation of risk in high-score patients.

CONCLUSION

This study identified four significant risk factors for recanalization after coil embolization and proposed a practical, externally validated risk score. The model provides clinically relevant risk stratification and may support individualized follow-up strategies.

Interdependence of First-coil and Global volume embolization ratios (VERs) calculated by Sim&Size in predicting aneurysm occlusion outcomes

BackgroundCoil embolization is a standard therapeutic approach for intracranial aneurysms. Recurrence risk during follow-up is not negligible, with inadequate packing density identified as a potential risk factor. This study aims to identify patient- and procedure-related factors contributing to recurrence.MethodsWe retrospectively enrolled consecutive patients with unruptured intracranial aneurysms treated only with coils between January 2021 and December 2022. Aneurysms were included if 3D-rotational angiography and follow-up imaging were available. For each patient, the volume embolization ratio (VER) was computed using Sim&Size® (Sim&Cure, France) for both the framing coil (First-coil VER) and the entire coiling procedure (Global VER). Patient demographics and aneurysm characteristics were also recorded. Follow-up imaging classified patients into adequate- or inadequate-occlusion groups. Multivariate analyses assessed independent factors associated with recurrence.ResultsSeventy-nine unruptured aneurysms from 79 patients were included. At follow-up, n = 69 (87%) demonstrated adequate occlusion, defined as modified Raymond-Roy classification I-II. Adequate- and inadequate-occlusion groups differed in First-coil (13.5 ± 5.5% vs 7.1 ± 4.0% respectively, P = .002) and Global VER (24.5 ± 6.8% vs 17.3 ± 5.7% respectively, P = .004). Posterior aneurysm location (P = .013), aneurysm height (P = .007), and neck diameter (P = .018) were significantly associated with recurrence. In multivariate analysis, Global- (P = .029) and First-coil VER (P = .025) remained significant risk factors for recurrence, with their interaction term being statistically significant as well (P = .020).ConclusionsFirst-coil and Global VER computed using Sim&Size® are predictive of aneurysm occlusion at follow-up. These results highlight the potential value of virtual simulation in optimizing coil packing density to improve mid- to long-term occlusion outcomes.

Retreatment rate and strategies for recurrent and residual aneurysms after Woven EndoBridge (WEB) treatment: a comprehensive systematic review and meta-analysis

Woven Endo Bridge (WEB) is a flow diverter device used to treat wide-necked intracranial aneurysms. We conducted a systematic review and meta-analysis to determine the retreatment rate and strategies following aneurysmal recurrence after WEB treatment. A systematic literature search was conducted through four electronic databases. The Cochrane risk of bias tool for non-randomized trials (ROBINS-I) was used for risk of bias assessment. A meta-analysis and meta-regression were performed on relevant variables. A total of 29 studies with 2067 patients were included. Initially treated aneurysms had an adequate occlusion rate of 84.7% (20 studies, 980/1156, 95%CI: 79%-89%) at the last follow-up. The overall retreatment rate was 8.6% (24 studies, 251/2893, 95%CI: 6.5%-10.9%). Following retreatment, the immediate complete occlusion rate post retreatment and complete occlusion rate at last follow-up were 52% (six studies, 95%CI, 11%-91%) and 65% (six studies, 77/120, 95%CI: 56%-73%) respectively. Stent-assisted coiling achieved a 100% (95%CI: 57%-100%, P-value < 0.01) immediate adequate occlusion rate and 74% complete occlusion rate (95%CI: 16%-100%, P-value = 0.63) at last follow-up, which was higher than clipping, coiling, and flow diversion. On meta-regression, aneurysm height and neck width significantly associated with higher retreatment rate. The current meta-analysis showed a 9% retreatment rate after initial aneurysms treatment with WEB and overall adequate retreatment occlusion was high. Although stent-assisted coiling showed a higher adequate occlusion rate post-operatively, there was no significant difference between retreatment strategies in long-term radiological outcomes.

Evaluation of Early Recurrence after Coil Embolization for Ruptured Anterior Communicating Artery Aneurysms

Objective

We retrospectively examined the risk factors for early recurrence in patients with ruptured anterior communicating artery (AcomA) aneurysms who underwent coil embolization.

Methods

Forty-four patients with ruptured AcomA aneurysms who underwent coil embolization between January 2012 and June 2021 were included. Patient backgrounds, anatomical features, intraoperative anticoagulation, and radiological findings before and after treatment were reviewed retrospectively. Univariate analysis was performed separately for each item investigated in the early recurrence (ER) and non-early recurrence (NER) groups. Additionally, the relationship between changes in embolic status (Raymond-Roy classification [RRC]) from immediately after surgery to 2 weeks later and severity of disease was investigated.

Results

Re-treatment was performed in a total of 8 (18.2%) cases. Two cases were detected and treated in the chronic phase with no re-rupture. In the ER group, 6 (13.6%) cases had RRC class 3 filling without evidence of coil compaction on digital subtraction angiography performed 2 weeks after the initial embolization, and were re-treated. The mean intraoperative activated clotting time (ACT; p = 0.0226; NER median 189.5 s, ER median 149 s), contralateral A1 diameter (p = 0.0264; NER median 0.85 mm, ER median 0.26 mm), and volume embolization rate (VER; p = 0.02, NER median 35.57%, ER median 20.86%) were significantly lower in the ER group. The more severe the Hunt and Hess grade, the worse the embolic condition (RRC) tended to be after 2 weeks (p = 0.0339).

Conclusion

In this study, factors such as low intraoperative ACT, low VER, contralateral A1 hypoplasia, and condition severity may be associated with early recurrence after acute coil embolization for ruptured AcomA aneurysms.

Recurrence rate of intracranial aneurysms: a systematic review and a meta-analysis comparing craniotomy and endovascular coiling

Patients with intracranial aneurysm (IA) are at high risk of cerebral hemorrhage, which is associated with high mortality. Craniotomy or interventional endovascular coiling are common treatment methods in clinical practice, depending on the patient's condition. However, the recurrence rate of IA after either method remains unclear. This meta-analysis was conducted to study the relationship between different treatment regimens and IA recurrence. PubMed, CNKI, Web of Science, Wan Fang, and VIP databases were used to identify studies on "intracranial aneurysm," "craniotomy," "endovascular coiling," and "recurrence rate." Included studies adhered to rigorous screening and diagnostic criteria, and statistical models were applied based on homogeneity testing. This study encompassed 28 articles, including five on craniotomy and 23 on endovascular coiling, published between 2007 and 2022; among 1,448 cases treated with craniotomy, 20 experienced recurrences (recurrence rate: 1.4%, 95% CI: 0.2%), while among 5,975 cases treated with endovascular coiling, 872 cases experienced recurrence (recurrence rate: 14.6%, 95% CI: 14%, 20%). High heterogeneity (87%) was observed in the endovascular coiling, likely due to differences in patient demographics and aneurysm characteristics. For IAs, although endovascular coiling has advantages in terms of lower trauma and faster recovery, its high recurrence rate warrants closer post-treatment monitoring. Despite being more invasive, Craniotomy may be preferable in specific cases, such as when treating aneurysms with complex shapes or challenging locations. Treatment choice should be individualized, and future advancements in endovascular coiling technologies may help reduce recurrence rates.

Drill turn technique for enhanced visualization of wide-neck bifurcation aneurysms in Y-stent-assisted coiling with LVIS EVO stents: technical considerations and mid-term results

BACKGROUND

Crossing Y-stent-assisted coiling (CYSAC) is a feasible yet technically challenging technique for the treatment of wide-neck bifurcation aneurysms (WNBAs).

OBJECTIVE

To present mid-term results of Y-stent-assisted coiling (YSAC) using the LVIS EVO stent and to describe our "drill turn" technique for stent crossing.

METHODS

This retrospective, observational study included 37 consecutive patients treated with YSAC using LVIS EVO stents at five centres between September 2020 and March 2023.

RESULTS

Immediately after treatment, 31 of the 37 patients (83.8%) achieved Raymond-Roy occlusion classification (RROC) Class I occlusion, while 5 patients (13.5%) had Class II and 1 patient (2.7%) had Class III occlusion. The mean follow-up period was 32.8 months (range: 11-41 months), and all patients underwent follow-up imaging after ≥ 6 months. On follow-up imaging, 34 patients (92%), including all those with immediate RROC Class I occlusion, 2 with Class II, and 1 with Class III, showed Class I occlusion. One patient with RROC Class II occlusion demonstrated a gradual decrease in residual filling, while one large partially thrombosed middle cerebral artery aneurysm and one large basilar tip aneurysm (8%) with residual neck filling remained unchanged on the 6-month digital subtraction angiograph.

CONCLUSION

Utilizing the described drill turn technique, CYSAC with LVIS EVO stents was found to be feasible and safe for WNBA treatment, with high and stable occlusion rates observed during mid-term follow-up.

Long-Term Hemorrhage and Reperfusion Rates of Coiled Aneurysms: A Single-Center Experience

Background: The endovascular approach has emerged as standard therapy for many intracranial aneurysms (IAs) to prevent hemorrhage, yet its long-term durability varies considerably. The aim of this study was to evaluate the safety and effectiveness of an initially deliberate endovascular approach regarding IA hemorrhage rates over a long-term follow-up period. Methods: This retrospective single-center study included all consecutive patients with endovascularly treated IAs who presented between January 2008 and December 2020 with a follow-up of at least 12 months. The primary endpoint was the proportion of patients with long-term IA hemorrhage rates and reperfusion. The secondary endpoint was treatment-related morbidity and mortality. Independent risk factors for IA reperfusion over the long term were analyzed using multivariate logistic regression. Results: Endovascular treatment was the therapy of choice for 333 patients with IAs, among whom 188 (57%) experienced rupture upon presentation. Complete coiling (Raymond I) was noted in 162 (49%) of the patients, with primary supportive devices being used in 51 (15%) patients. After a median (±SD) follow-up time of 34 ± 41 months (range 12-265 months), IA reperfusion was noted in 158 (47%), necessitating retreatment in 105 (32%) of the patients. Over the long term, hemorrhage was noted in four (1%) patients. Multivariate analysis revealed aneurysmal multilobarity (HR 1.8, 95%CI 1.2-2.7; p = 0.004) and a patient age of ≥50 years (HR 1.7, 95% CI 1.1-2.5, p = 0.01) as independent predictors of reperfusion over time. Intervention-related morbidity was noted in 16 (4.8%) patients, namely, thrombosis formation and contrast extravasation in 8 (2.4%) patients each, while no intervention-induced mortality was observed. Conclusion: In the long term, the hemorrhage rate in patients with IA with an initially more conservative endovascular approach is low. Therefore, a deliberate endovascular treatment approach might be justified.

A 5-Year Follow-Up after Endovascular Treatment of 402 Intracranial Aneurysms-A Single-Centre Experience

The aim of our study was to evaluate the early and long-term clinical and morphological outcomes of the endovascular treatment of ruptured and non-ruptured intracranial aneurysms in a cohort of patients from a single centre. We retrospectively analysed the treatment outcomes of 402 endovascularly treated intracranial aneurysms with an average follow-up of 5.5 years. All included patients were treated with endovascular techniques (coil, stent or both). We analysed patient demographics, risk factors for an aneurysm rupture, aneurysm characteristics, and clinical and angiographic complications and outcomes. We analysed and compared the data from the two groups, ruptured aneurysms (RAs) and unruptured aneurysms (UAs), separately. Out of the 318 patients included, a good early clinical outcome was achieved in 78.5% of RAs and in 95.3% of UAs. No complications occurred in 87.71% of patients with UAs and in 80.45% with RAs. The periprocedural rupture rate for UAs and RAs was 0.8% and 2.2%, respectively. The rate of thromboembolic events was 4.8 and 8% for UAs and RAs, respectively. A retreatment due to the recanalisation was required in 9.21% of patients with UAs and in 16.66% of patients with RAs. The results from our centre showed an overall favourable clinical outcome with acceptable periprocedural complications for both RAs and UR aneurysms and proved the endovascular method as safe and effective in the treatment of intracranial aneurysms.

Progression from Early Minor Recanalization to Major Recanalization in Ruptured Intracranial Aneurysms After Successful Coil Embolization: Risk Factors and Proposal of a Novel Predicting Variable

BACKGROUND

The risk factors for the progression from early minor recanalization to major recanalization are not well established. Herein, we evaluated ruptured intracranial aneurysms (IAs) with minor recanalization within 1 year of coiling and their progression to major recurrence.

METHODS

We retrospectively reviewed our database of coiled IAs and searched for ruptured saccular IAs that were successfully embolized without residual sacs. We selected IAs with minor recanalization confirmed on radiological studies within 1 year of coil embolization. All the IA cases had a follow-up period longer than 36 months based on the radiological results.

RESULTS

Minor recanalization occurred in 45 IAs within 1 year of coil embolization. Among them, 14 IAs (31.1%) progressed to major recanalization, and 31 remained stable. Progression to major recanalization was detected 12 months after minor recanalization in 2 patients, 24 months in 7 patients, and 36 months in 5 patients. Moreover, the progression to major recanalization occurred more frequently in IAs at the posterior location (P = 0.024, odds ratio 11.20) and IAs with a proportional forced area > 9 mm2 (P = 0.002, odds ratio 17.13), which was a newly proposed variable in the present study.

CONCLUSIONS

Our results showed that approximately one third of the ruptured IAs with early minor recanalization after coiling progressed to major recanalization within 3 years. Physicians should focus on the progression of ruptured IAs from minor to major recanalization, especially those with a posterior circulation location and a proportional forced area >9 mm2.

A predictive model for the recurrence of intracranial aneurysms following coil embolization

Objective

This study aimed to identify risk factors for intracranial aneurysms (IAs) recurrence and establish a predictive model to aid evaluation.

Methods

A total of 302 patients with 312 IAs undergoing coil embolization between September 2017 and October 2022 were divided into two groups based on digital subtraction angiography follow-up. Clinical characteristics, operation-related factors, and morphologies were measured. Cox proportional hazard regression was used to identify the risk factors. Hazard ratios (HRs) were used to score points, and a predictive model was established. The test cohorts consisted of 51 IAs. Receiver operating characteristic curves were generated to determine the cutoff values and area under the curves (AUCs). A Delong test was performed to compare the AUCs.

Results

Diameter maximum (D max) (p < 0.001, HR = 1.221), Raymond-Roy occlusion classification (RROC) II or III (p = 0.004, HR = 2.852), and ruptured status (p < 0.001, HR = 7.782) were independent risk factors for the recurrence of IAs. A predictive model was established: D max + 2 * RROC (II or III; yes = 1, no = 0) + 6 * ruptured status (yes = 1; no = 0). The AUC of the predictive model (0.818) was significantly higher than those of D max (0.704), RROC (II or III) (0.645), and rupture status (0.683), respectively (Delong test, p < 0.05). The cutoff values of the predictive model and D max were 9.75 points and 6.65 mm, respectively.

Conclusion

The D max, RROC (II or III), and ruptured status could independently predict the recurrence of IAs after coil embolization. Our model could aid in practical evaluations.

Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis

OBJECTIVE

We aimed to compare the efficacy and safety of microsurgical clipping versus endovascular treatment (EVT) for paraclinoid aneurysms.

METHODS

A systematic search for studies including patients with paraclinoid aneurysms treated with a microsurgical or endovascular technique was conducted in 6 databases from inception to February 2022. Efficacy outcomes included complete angiographic occlusion at last follow-up, favorable functional outcome, and recurrence of the aneurysm. For safety, we assessed a composite of intraoperative and postoperative complications. Data were pooled using a random-effects model.

RESULTS

A total of 95 studies including 6711 patients, 3029 in the surgical group and 3682 in the EVT group were found. Pooled rates of complete occlusion were 94% (95% CI 91%-96%; I2 = 0%) in the surgical group and 69% (95% CI 63%-74%; I2 = 79%) in the EVT group, respectively. The favorable functional outcome rate was 86% (95% CI 76%-92%; I2 = 72%) with surgical treatment and 95% (95% CI 92%-97%; I2 = 61%) with EVT. The rate of aneurysm recurrence with surgical treatment was 1% (95% CI 0%-4%; I2 = 0%) and 12% (95% CI 9%-16%; I2 = 57%) with EVT. The composite safety outcome rate in the surgical group was 24% (95% CI 18%-30%; I2 = 90%) and 10% (95% CI 8%-13%; I2 = 71%) in the EVT group.

CONCLUSIONS

Our findings suggest that microsurgical clipping seems to have a higher efficacy than EVT in terms of angiographic occlusion and aneurysm recurrence; however, EVT seems to be safer in terms of intraoperative and postoperative complications. Considering the heterogeneity and low-level evidence of the data available, further prospective randomized studies are warranted to confirm our findings.

The current landscape of intracranial aneurysms in Africa: management outcomes, challenges, and strategies-a narrative review

Intracranial aneurysms (IAs) pose complex and potentially life-threatening challenges in Africa, where limited resources, restricted access to specialised healthcare facilities, and disparities in healthcare provision amplify the difficulties of management. Timely diagnosis and treatment are pivotal in preventing complications, including subarachnoid haemorrhage. Treatment options encompass observation, surgical clipping, endovascular coiling, and flow diversion. Positive outcomes observed in IA management in Africa include high survival rates, favourable functional outcomes, successful treatment techniques, and the absence of complications in some cases. However, negative outcomes such as postoperative complications, reduced quality of life, perioperative mortality, and the risk of recurrence persist. Challenges in IA management encompass limited access to diagnostic tools, a scarcity of specialised healthcare professionals, and an unequal distribution of services. Addressing these challenges requires interventions focused on improving access to diagnostic tools, expanding the number of trained professionals, and establishing specialised IA treatment centres. Collaboration, research, and capacity-building efforts hold significant importance in improving patient outcomes and reducing disparities in IA management across Africa.

Risk factors for repeated recurrence of cerebral aneurysms treated with endovascular embolization

Purpose

To explore the risk factors of recurrence after second endovascular embolization of recurrent aneurysms and the characteristics of recurrent refractory aneurysms to help clinical decision-making.

Materials and methods

Forty-nine patients with recurrent aneurysms who underwent repeated embolization were retrospectively enrolled and divided into the recurrent and non-recurrent group. The risk factors of recurrence, complications and follow-up results of repeated embolization, and characteristics of recurrent refractory aneurysms were analyzed.

Results

Among the 49 patients with the second embolization, 5 were lost to follow-up, 9 recurred, and 35 did not. Univariate analysis showed that aneurysm size (P = 0.022), aneurysm classification (P = 0.014), and Raymond-Roy grade after the second embolization (P = 0.001) were statistically different between the two groups. Multivariate analysis demonstrated the Raymond-Roy grade as an independent risk factor for the recurrence of aneurysms after the second embolization (P = 0.042). The complication rate after the second embolization was 4%. There were five recurrent refractory aneurysms with an average aneurysm size of 23.17 ± 10.45 mm, including three giant aneurysms and two large aneurysms. To achieve complete or near-complete embolization of the recurrent refractory aneurysms, multiple treatment approaches were needed with multiple stents or flow diverting devices.

Conclusion

Aneurysm occlusion status after the second embolization is an independent risk factor for the recurrence of intracranial aneurysms. Compared with near-complete occlusion, complete occlusion can significantly reduce the risk of recurrence after second embolization. In order to achieve complete or near-complete occlusion, recurrent refractory aneurysms need multiple treatments with the use of multiple stents or flow diverting devices.