Long-term clinical and angiographic follow-up results of the dual-layer flow diverter device (FRED) for the treatment of intracranial aneurysms in a multicenter study

Long-term Follow-up After Aneurysm Treatment with the Flow Redirection Endoluminal Device (FRED) Flow Diverter

INTRODUCTION

This study focuses on long-term outcomes after aneurysm treatment with either the Flow Re-Direction Endoluminal Device (FRED) or the FRED Jr. to investigate the durability of treatment effect and long-term complications.

METHODS

This study is based on a retrospective analysis of a prospectively maintained patient data base. Patients treated with either FRED or FRED Jr. between 2013 and 2017 at our institution, and thus a possibility for ≥ 5 years of follow-up, were included. Aneurysm occlusion rates, recurrence rates, modified Rankin scale score shifts to baseline, and delayed complications were assessed.

RESULTS

In this study 68 patients with 84 aneurysms had long-term follow-up with a mean duration of 57.3 months and 44 patients harboring 52 aneurysms had a follow-up ≥ 5 years with a mean follow-up period of 69.2 months. Complete occlusion was reached in 77.4% at 2 years and increased to 84.9% when the latest available imaging result was considered. Younger age and the absence of branch involvement were predictors for aneurysm occlusion in linear regression analysis. After the 2‑year threshold, there were 3 reported symptomatic non-serious adverse events. Of these, one patient had a minor stroke, one a transitory ischemic attack and one had persistent mass effect symptoms due to a giant aneurysm, none of these resulted in subsequent neurological disability.

CONCLUSION

This long-term follow-up study demonstrates that the FRED and FRED Jr. are safe and effective for the treatment of cerebral aneurysms in the long term, with high rates of complete occlusion and low rates of delayed adverse events.

Flow diverter stents for endovascular treatment of aneurysms: a comparative study of efficacy and safety between FREDX and FRED

BACKGROUND

The FRED X flow diverter (FREDX), as the second generation in the FRED series, aims to improve the treatment of cerebral aneurysms. This study compares the efficacy and safety of FREDX with its predecessor, FRED.

METHODS

This prospective registry included patients treated with FRED and FREDX devices. Efficacy was assessed using digital subtraction angiography with 3D volumetric reconstruction at immediate and 1 year follow-ups. Safety was evaluated by recording complications, analyzed through univariate contrasts, generalized mixed models, and Bayesian network analyses.

RESULTS

We treated 287 patients with 385 aneurysms, with 77.9% receiving FRED and 22.1% FREDX. The median age was 55 years (IQR 47-65) and 78.4% were women. The FREDX group showed a higher prevalence of saccular-like aneurysms (70.6% vs 52.7%, P=0.012) and a higher rate of complete occlusion compared with FRED interventions (79.4% vs 59.3%, P=0.022). After adjusting for confounders, these differences represented a 3.04-fold increased likelihood (95% CI 1.44 to 6.41, P=0.003) of achieving complete occlusion at 1 year with FREDX interventions. Regarding safety, two (3.5%) complications (both non-symptomatic) were observed in the FREDX group and 23 (10.4%) in the FRED group (P=0.166). Bayesian network analysis suggested a trend towards fewer complications for FREDX, with a median reduction of 5.5% in the posterior distribution of the prevalence of complications compared with FRED interventions.

CONCLUSIONS

The FREDX device shows improved complete occlusion rates at 1 year compared with the FRED device while maintaining a favourable safety profile, indicating its potential advantage in the treatment of cerebral aneurysms.

Aneurysm Isolation is Associated with Complete Occlusion of Aneurysms After Flow Diverter Treatment

PURPOSE

Some aneurysms remain patent after treatment with flow diverters (FD) due to residual blood flow in the aneurysm. Several studies have proposed that branches and residual flow are associated with delayed aneurysm occlusion. We propose that aneurysm isolation (i.e., the complete disconnection of the aneurysm from surrounding vessels) might be a possible factor facilitating aneurysm occlusion. This study aimed to determine if aneurysm isolation was a factor associated with aneurysm occlusion after FD treatment.

METHODS

We reviewed 80 internal carotid artery (ICA) aneurysms treated with FDs between October 2014 and April 2021. Aneurysm isolation was assessed in high-resolution cone-beam computed tomograms at the end of each treatment. Aneurysms with incorporated branches and those with connections to other branches due to stent malapposition were deemed to be nonisolated. Other factors, such as patient age, sex, anticoagulant use, aneurysm size, adjunct coil use, and the presence of incorporated branches, were considered. The degree of aneurysm occlusion (complete or incomplete) was assessed by follow-up angiograms 12 months after treatment.

RESULTS

Complete occlusion was achieved in 57 of 80 aneurysms (71%). Completely occluded aneurysms had a significantly higher ratio of isolation compared to incompletely occluded aneurysms (91.2% vs. 69.6%, P = 0.032). Multivariate logistic regression analysis showed that aneurysm isolation was the sole significant predictor of complete aneurysm occlusion (odds ratio, OR 19.38; 95% confidence interval, CI 2.280-164.657; P = 0.007).

CONCLUSION

Aneurysm isolation is a significant factor contributing to complete occlusion after FD treatment.

The incidence and predictors of in-stent stenosis after pipeline flow-diverter stenting for intracranial aneurysm treatment

Background and purpose

Data on in-stent stenosis (ISS) following the flow diverter (FD) implantation method are scarce and inconsistent. In the present study, we sought to determine the incidence of ISS and identify the factors that predict its severity via the use of ordinal logistic regression.

Methods

A retrospective review of our center's electronic database was conducted to identify all patients with intracranial aneurysms (IAs) who received pipeline embolization device (PED) implantation between 2016 and 2020. Patient demographics, aneurysm characteristics, procedural information, and clinical and angiographic outcomes were reviewed. ISS was quantitatively assessed on angiographic follow-ups and graded as mild (<25%), moderate (25-50%), or severe (>50%). Ordinal logistic regression was conducted to determine the predictors of stenosis severity.

Results

A total of 240 patients with 252 aneurysms treated in 252 procedures were enrolled in this study. ISS has been detected in 135 (53.6%) lesions, with a mean follow-up time of 6.53 ± 3.26 months. The ISS was mild in 66 (48.9%) cases, moderate in 52 (38.5%) cases, and severe in 17 (12.6%) cases. All patients were asymptomatic, except for two of them with severe stenosis who presented with symptoms of acute cerebral thrombosis. Ordinal logistic regression identified that younger age and a longer procedure duration were independent predictors of a higher likelihood of ISS.

Conclusion

ISS is a common angiographic finding after PED implantation for IAs and is presented as a largely benign course through long-term follow-up. Patients who were younger in age and had a longer procedure duration were found to be at a greater risk of developing ISS.

Flow Diverting Stents in Cerebral Small Caliber Vessels (< 2 mm) for Aneurysm Treatment : A Three Center Retrospective Study

PURPOSE

The off-label use of flow diverting stents (FDS) for treating cerebral aneurysms in small distal vessels is increasing in clinical practice with encouraging results; however, data directly addressing the parent vessel size are still scarce. Our aim was to evaluate the safety and efficacy of FDS placement in anterior and posterior circulation aneurysms with parent arteries ≤ 2 mm in a real-world representative setting.

METHODS

We retrospectively reviewed patients treated with FDS at the three participating university hospitals between 2009 and 2021. The inclusion criteria were the placement of at least one FDS in a parent vessel with a maximum diameter of 2 mm or less. The primary clinical safety endpoint was the absence of death, major or minor symptomatic stroke, transient ischemic attack and procedure-related intracranial hemorrhage. Clinical outcome was assessed using the modified Rankin Scale (mRS) score at the follow-up visit at 1 year. The primary efficacy endpoint was defined as complete and near-complete occlusion at the 1‑year follow-up.

RESULTS

We identified 55 patients harboring 56 aneurysms. The primary clinical safety endpoint was obtained in 93% of cases. The hemorrhagic and thromboembolic complication rates were 4% and 9%, respectively. No patient died or had a relevant discrepancy (> 1 point) at the pre-mRS and post-mRS. The primary efficacy endpoint was reached in 80% of cases.

CONCLUSION

The use of FDS in vessels < 2 mm is technically feasible with good aneurysm occlusion rates and an acceptable safety profile. Nevertheless, it is essential to be aware of the of the main complications associated when operating in small diameter vessels.

Endovascular treatment of unruptured intracranial aneurysms with flow diverters: A retrospective long-term single center analysis

PURPOSE

The introduction of flow diverters (FDs) in 2007 greatly enhanced the treatment of intracranial aneurysms. Here, we present our long-term clinical experience in treating unruptured intracranial aneurysms with FDs.

METHODS

107 patients with unruptured aneurysms and treated with an FD between 2010 and 2019 were retrospectively reviewed. Aneurysm occlusion, procedural complications, and clinical outcome were evaluated.

RESULTS

Angiographic follow-up was available for 93 patients with a mean long-term follow-up time of 28.4 ± 21.6 months. Additional coiling was performed in 15.1% of patients (n = 14). Adequate aneurysm occlusion (Kamran grades 3 and 4) at long-term follow-up was achieved in 94.6% of patients (n = 88). 3.2% (n = 3) required endovascular retreatment since the last follow-up showed a lack of aneurysm occlusion (Kamran grade 0) due to a foreshortening of the FD. Incomplete opening of the FD and parent vessel occlusion was seen in 1.1% (n = 1) and 3.2% (n = 3) of patients, respectively. In-stent stenosis was observed in 57% (n = 53) of cases at short-term follow-up and 22.6% (n = 21) at long-term, which were moderate and asymptomatic overall. In-stent stenosis decreased significantly between short- and long-term follow-ups (31.4 ± 17.0% vs 9.7 ± 13.6%, respectively; p ≤ 0.001). Thromboembolic and hemorrhagic events occurred in 7.5% (n = 7) and 1.1% (n = 1) of patients, respectively. Good clinical outcome (modified Rankin scale: 0-2) was obtained in 97.8% (n = 91) leading to an overall treatment-related morbidity of 2.2% (n = 2). There was no procedural mortality.

CONCLUSION

Our study shows that FD treatment of unruptured intracranial aneurysms is effective and safe with high occlusion rates and low rates of permanent morbidity at long-term follow-up.

North American multicenter experience with the Flow Redirection Endoluminal Device in the treatment of intracranial aneurysms

OBJECTIVE

Flow diverters have revolutionized the endovascular treatment of intracranial aneurysms. Here, the authors present the first large-scale North American multicenter experience using the Flow Redirection Endoluminal Device (FRED) in the treatment of cerebral aneurysms.

METHODS

Consecutive cerebral aneurysms treated with FRED at 7 North American centers between June 2020 and November 2021 were included. Data collected included patient demographic characteristics, aneurysm characteristics, periprocedural and long-term complications, modified Rankin Scale (mRS) scores, and radiological follow-up.

RESULTS

In total, 133 aneurysms in 116 patients were treated with 123 FRED deployment procedures and included in this study. One hundred twenty-six aneurysms (94.7%) were unruptured, 117 (88.0%) saccular, and 123 (92.5%) located in anterior circulation. The mean (range) aneurysm maximal width and neck width sizes were 7.2 (1.5-42.5) mm and 4.1 (1.0-15.1) mm, respectively. Successful FRED deployment was achieved in 122 procedures (99.2%). Adjunctive coiling was used in 4 procedures (3.3%). Radiological follow-up was available for 101 aneurysms at a median duration of 7.0 months. At last follow-up, complete occlusion was observed in 55.4% of patients, residual neck in 8.9%, and filling aneurysm in 35.6%; among cases with radiological follow-up duration > 10 months, these values were 21/43 (48.8%), 3/43 (7.0%), and 19/43 (44.2%), respectively. On multivariate regression analysis, age (OR 0.93, p = 0.001) and aneurysm neck size (OR 0.83, p = 0.048) were negatively correlated with odds of complete occlusion at latest follow-up. The retreatment rate was 6/124 (4.8%). The overall complication rate was 31/116 (26.7%). Parent vessel occlusion, covered branch occlusion, and in-stent stenosis were detected in 9/99 (9.1%), 6/63 (9.5%), and 15/99 (15.2%) cases, respectively. The FRED-related, symptomatic, thromboembolic, and hemorrhagic complication rates were 22.4%, 12.9%, 6.9%, and 0.9% respectively. The morbidity rate was 10/116 patients (8.6%). There was 1 death due to massive periprocedural internal carotid artery stroke, and 3.6% of the patients had an mRS score > 2 at the last follow-up (vs 0.9% at baseline).

CONCLUSIONS

As the first large-scale North American multicenter FRED experience, this study confirmed the ease of successful FRED deployment but suggested lower efficacy and a higher rate of complications than reported by previous European and South American studies on FRED and other flow-diverting devices. The authors recommend judicious use of this device until future studies can better elucidate the long-term outcomes of FRED treatment.

Diversion-p64: results from an international, prospective, multicenter, single-arm post-market study to assess the safety and effectiveness of the p64 flow modulation device

BACKGROUND

The use of flow diversion to treat intracranial aneurysms has increased in recent years.

OBJECTIVE

To assess the safety and angiographic efficacy of the p64 flow modulation device.

METHODS

Diversion-p64 is an international, prospective, multicenter, single-arm, study conducted at 26 centers. The p64 flow modulation device was used to treat anterior circulation aneurysms between December 2015 and January 2019. The primary safety endpoint was the incidence of major stroke or neurologic death at 3-6 months, with the primary efficacy endpoint being complete aneurysm occlusion (Raymond-Roy Occlusion Classification 1) on follow-up angiography.

RESULTS

A total of 420 patients met the eligibility criteria and underwent treatment with the p64 flow modulation device (mean age 55±12.0 years, 86.2% female). Mean aneurysm dome width was 6.99±5.28 mm and neck width 4.47±2.28 mm. Mean number of devices implanted per patient was 1.06±0.47, with adjunctive coiling performed in 14.0% of the cases. At the second angiographic follow-up (mean 375±73 days), available for 343 patients (81.7%), complete aneurysm occlusion was seen in 287 (83.7%) patients. Safety data were available for 413 patients (98.3%) at the first follow-up (mean 145±43 days) with a composite morbidity/mortality rate of 2.42% (n=10).

CONCLUSIONS

Diversion-p64 is the largest prospective study using the p64 flow modulation device. The results of this study demonstrate that the device has a high efficacy and carries a low rate of mortality and permanent morbidity.

Long-term results and comparison of flow re-direction endoluminal device and pipeline embolization device in endovascular treatment of intracranial carotid aneurysms

OBJECTIVE

This study aims to compare the efficacy, safety, and long-term outcomes of two flow diverters, i.e., pipeline embolization device and flow re-direction endoluminal device, in the treatment of distal carotid aneurysms.

METHODS

A total of 138 patients with 175 aneurysms were included from February 2012 to September 2019. Ninety-nine aneurysms were treated with flow re-direction endoluminal device and 76 with pipeline embolization device. Angiographic follow-ups were at the 6th, 12th, 24th, 36th, and 60th months; the O'Kelly-Marotta grading scale was used to assess aneurysms occlusion. Outcomes of two devices were compared; possible associations regarding patient characteristics, aneurysm properties, treatment details, and adverse events were evaluated.

RESULTS

The mean follow-up period was 33 months, with 10 patients lost to follow-up. Occlusion rates at the 6th and 12th months and during the last follow-up were similar for flow re-direction endoluminal device (81%, 84%, and 90%) and pipeline embolization device (82%, 85%, and 93%). Occlusion rates were also similar after stand-alone use without coiling. There was no significant difference regarding adverse event rates with a 10.9% overall complication rate, 3.6% mortality, and 0.7% permanent morbidity. All the mortality and morbidity were related to hemorrhagic complications. Device deployment failure was observed with five flow re-direction endoluminal devices and two pipeline embolization devices, whereas two severe in-stent stenoses occurred with each device.

CONCLUSIONS

Both flow re-direction endoluminal device and pipeline embolization device are feasible and effective in flow diversion of distal internal carotid artery aneurysms, with similar adverse events rates and aneurysm occlusion success. Aneurysm occlusion rates increase with time, while the presence of an integrated branch significantly decreases treatment success.

Brazilian FRED Registry: A Prospective Multicenter Study for Brain Aneurysm Treatment-The BRED Study

BACKGROUND AND PURPOSE

The development of flow diverters has changed the endovascular approach to intracranial aneurysms. On the basis of good results, the indications for flow diverters have expanded to include aneurysms of different shapes, locations, and sizes. The objective of the study was to report on the performance of the Flow Re-Direction Endoluminal Device (FRED) in intracranial aneurysm treatment at early and medium-term follow-up.

MATERIALS AND METHODS

This single-arm, multicentric, prospective, observational study assessed aneurysm treatment with the FRED. The primary outcome was complete aneurysm occlusion at 6 and 12 months, and the secondary outcome was to evaluate the safety of the FRED with respect to stroke and death rates.

RESULTS

Between June 2016 and August 2018, a total of 100 consecutive patients with 131 aneurysms were treated in 107 procedures. Total occlusion rates were 91% and 95% at 6 and 12 months. There was 1 death, and the total final morbidity rate was 1.8%. The complication rate was 4.6%.

CONCLUSIONS

As reported previously, the FRED has proved to be a safe and effective tool, with high occlusion rates. The design of the stent makes it more difficult to perform balloon angioplasty compared with similar devices. A branch arising from the aneurysm sac was found to be a predictor of nonocclusion at 12 months, though larger series are needed to estimate the magnitude of the association.

Flow redirection endoluminal device (FRED) for treatment of intracranial aneurysms: A systematic review

INTRODUCTION

The Flow Redirection Endoluminal Device (FRED; MicroVention) is a dual-layered flow diverter used for the treatment of intracranial aneurysms. The objective of this systematic review was to compile device-related safety and effectiveness data.

METHODS

The literature from January 1, 2013 to April 30, 2021 was searched for studies describing use of the FRED for intracranial aneurysm treatment irrespective of aneurysm location and morphology. The review included anterior and posterior circulation ruptured and unruptured saccular, fusiform or dissection, and blister aneurysms. MeSH terms related to "flow re-direction endoluminal device" and "FRED for aneurysms" were used. Data related to indication, complications, and rates of aneurysm occlusion were retrieved and analyzed.

RESULTS

Twenty-two studies with 1729 intracranial aneurysms were included in this review. Overall reported morbidity was 3.9% (range 0-20%). Overall procedure-related mortality was 1.4% (range 0-6%). Complication rates fell into 5 categories: technical (3.6%), ischemic (3.8%), thrombotic or stenotic (6%), hemorrhagic (1.5%), and non-neurological (0.8%). The aneurysm occlusion rate between 0 and 3 months (reported in 11 studies) was 47.8%. The occlusion rate between 4 and 6 months (reported in 14 studies) was 73.8%. Occlusion rates continued to increase to 75.1% at 7-12 months (reported in 10 studies) and 86.6% for follow-up beyond 1 year (reported in 10 studies).

CONCLUSION

This review indicated that the FRED is a safe and effective for the treatment of intracranial aneurysms. Future studies should directly compare the FRED with other flow diverters for a better understanding of comparative safety and effectiveness among the different devices.