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The Silk Vista Baby Study: A Multicenter Aneurysm Report From North America and Europe. BACKGROUND AND OBJECTIVES: The Silk Vista Baby (SVB) flow diverter (FD) stent (Balt SAS) is the first device designed for treating distally located brain aneurysms. It can be delivered through a 0.017-inch ID microcatheter, enabling access to small, distal vessels. The aim of this study was to evaluate the effectiveness, safety, technical success, occlusion rate, and clinical outcomes of the SVB device. METHODS: This retrospective, multicenter study included data from 18 centers from November 2023 to September 2024. Procedures were performed by experienced neurointerventionalists following institutional standards of care. Outcomes analyzed included effectiveness, safety, and aneurysm occlusion rates. Descriptive analyses and Pearson χ 2 or Independent t -Test were used for statistical evaluation. RESULTS: A total of 95 patients, mean age 55.4 years, were included. A total of 31% of aneurysms were ruptured at admission. Most (58.3%) were located in the anterior circulation, and 45% had previous treatment, mainly coiling (69.4%). Complication rates were higher for ruptured aneurysms (24.1%) compared with unruptured ones (9.2%). Two deaths occurred, 1 (1.1%) related to the procedure. At discharge, 87% of patients had modified Rankin Scale ≤2. The latest follow-up showed overall complete/near-complete occlusion rates of 76.1%, with 81.14% for ruptured and 73.43% for unruptured aneurysms. Technical success was higher in unruptured cases (100% vs 93.1%). CONCLUSION: Our case series demonstrated the efficacy of the SVB with a high rate of technical success. The occlusion rates for ruptured cases are comparable with those of other FDs. However, the rates are lower for unruptured cases. This discrepancy is likely due to the characteristics of the aneurysms, particularly in the presence of side branches in bifurcation lesions. The SVB safety profile is similar to other FDs in unruptured cases, while the ruptured group presented more complications.

This is a retrospective, multicenter experience involving primarily patients from North America (17 Centers in the United States [US] and 1 Center in Canada) and 1 center in Austria between November 2023 and September 2024. Local ethics committees and/or institutional review boards at each institution approved the retrospective analysis of deidentified patient data, which did not require informed consent. Inclusion criteria encompassed all consecutive patients with intracranial aneurysms who were treated with the SVB device and had at least 1 imaging follow-up. Patients were excluded if there was no information regarding the outcome in the follow-ups. This study was performed according to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines.6 The data collected at each center were predefined by a study protocol and entered into a standardized data form, and imaging was reviewed by each center. Data included age, sex, race, clinical presentation, modified Rankin Score, comorbidities, family aneurysm history, index aneurysm features, rupture status, previous treatment, branch involvement, vessel dimensions, antiplatelet regimen, platelet test, SVB device details, adjunct coiling/stent use, angioplasty, complications, technical success, occlusion rates, and treatment-related issues.

e, comorbidities, family aneurysm history, index aneurysm features, rupture status, previous treatment, branch involvement, vessel dimensions, antiplatelet regimen, platelet test, SVB device details, adjunct coiling/stent use, angioplasty, complications, technical success, occlusion rates, and treatment-related issues. Complete occlusion was defined as Raymond-Roy (RR) classification I. Near-complete occlusion was defined as either RR I or RR II, and residual aneurysm was defined as RR III. Treatment complications were categorized into early (<30 days) and delayed (>30 days) events. Subjects were considered to have treatment-related morbidity if symptoms persisted for more than 30 days. Complications were further categorized by type; ischemic-thromboembolic complications were classified as symptomatic (whether persistent or transitory) or asymptomatic, as well as in-stent thrombosis. Additional procedure-related complications included aneurysm perforation, vessel dissection or perforation, hemorrhagic complications, postoperative aneurysm rupture, access complications, and others. Technical success was defined as achieving complete neck coverage and optimal wall apposition of the device after deployment, without requiring a second bail-out (unplanned) stent placement because of the first device experiencing malfunctions, such as failure to open.

neurysm rupture, access complications, and others. Technical success was defined as achieving complete neck coverage and optimal wall apposition of the device after deployment, without requiring a second bail-out (unplanned) stent placement because of the first device experiencing malfunctions, such as failure to open. Given the limitation of previous publications with limited sample size and heterogeneity because of the grouping of patients with ruptured and nonruptured aneurysms when reporting outcomes, our cohort was divided into 2 subgroups: ruptured and nonruptured aneurysms. The primary outcomes of this study included the following: (1) effectiveness, defined as the rate of near-complete occlusion (RRI + RII) in intracranial aneurysms treated with the SVB; (2) safety, defined as the rate of morbidity procedure–related complications (eg, the incidence of major stroke [ischemic or hemorrhagic] in the territory supplied by the treated artery and neurological death associated with the procedure). Additional outcomes included rates of complete aneurysm occlusion at follow-up, overall procedure-related complications, and mortality; procedure-related or delayed aneurysm rupture; and technical challenges included device shortening, angioplasty, and additional stent deployment. Additional outcomes included aneurysm rupture, mortality, and other complications.

te aneurysm occlusion at follow-up, overall procedure-related complications, and mortality; procedure-related or delayed aneurysm rupture; and technical challenges included device shortening, angioplasty, and additional stent deployment. Additional outcomes included aneurysm rupture, mortality, and other complications. The SVB is a FD designed specifically for deployment using a 0.017″ microcatheter, facilitating navigation through challenging and distal vessel anatomies. This design innovation allows the treatment of lesions previously considered untreatable by endovascular methods. The SVB is indicated for use in intracranial vessels with diameters ranging from 1.5 mm to 3.5 mm. The device is available commercially in the EU (Conformité Européenne mark on 12 May 2018) and in Canada (License Amendment on 15 March 2022). Since SVB has not yet gained commercial approval in the United States, all cases performed in the United States were approved through the Food and Drug Administration Expanded Access to Medical Device pathway.

ally in the EU (Conformité Européenne mark on 12 May 2018) and in Canada (License Amendment on 15 March 2022). Since SVB has not yet gained commercial approval in the United States, all cases performed in the United States were approved through the Food and Drug Administration Expanded Access to Medical Device pathway. The procedures were performed by experienced neurointerventionalists under either general anesthesia or local anesthesia with conscious sedation, using femoral or radial artery access. In elective cases, dual-antiplatelet therapy was initiated according to each institution's standard protocols, typically 5-7 days before the procedure. Antiplatelet responsiveness testing (eg, VerifyNow Accumetrics) was used when available. For urgent cases, an immediate antiplatelet loading dose was administered, or an intravenous antiplatelet agent (eg, cangrelor, eptifibatide) was used. The antiplatelet regimen was maintained for a minimum of 3 months postprocedure to ensure vessel patency and minimize thromboembolic risks. Categorical variables are presented as n and percentage, and continuous variables are presented as median with standard deviation. The Pearson χ2 test was used to compare categorical variables (eg, morbidity, mortality, complete occlusion, near-complete occlusion, presence of residual aneurysm, and technical success). Independent t-Test was used to compare continuous variables (eg, age, aneurysm neck, width, height, proximal and distal parent vessel diameters); P-values <0.05 were considered statistically significant.

This is a retrospective, multicenter experience involving primarily patients from North America (17 Centers in the United States [US] and 1 Center in Canada) and 1 center in Austria between November 2023 and September 2024. Local ethics committees and/or institutional review boards at each institution approved the retrospective analysis of deidentified patient data, which did not require informed consent. Inclusion criteria encompassed all consecutive patients with intracranial aneurysms who were treated with the SVB device and had at least 1 imaging follow-up. Patients were excluded if there was no information regarding the outcome in the follow-ups. This study was performed according to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines.6

The data collected at each center were predefined by a study protocol and entered into a standardized data form, and imaging was reviewed by each center. Data included age, sex, race, clinical presentation, modified Rankin Score, comorbidities, family aneurysm history, index aneurysm features, rupture status, previous treatment, branch involvement, vessel dimensions, antiplatelet regimen, platelet test, SVB device details, adjunct coiling/stent use, angioplasty, complications, technical success, occlusion rates, and treatment-related issues. Complete occlusion was defined as Raymond-Roy (RR) classification I. Near-complete occlusion was defined as either RR I or RR II, and residual aneurysm was defined as RR III. Treatment complications were categorized into early (<30 days) and delayed (>30 days) events. Subjects were considered to have treatment-related morbidity if symptoms persisted for more than 30 days. Complications were further categorized by type; ischemic-thromboembolic complications were classified as symptomatic (whether persistent or transitory) or asymptomatic, as well as in-stent thrombosis. Additional procedure-related complications included aneurysm perforation, vessel dissection or perforation, hemorrhagic complications, postoperative aneurysm rupture, access complications, and others. Technical success was defined as achieving complete neck coverage and optimal wall apposition of the device after deployment, without requiring a second bail-out (unplanned) stent placement because of the first device experiencing malfunctions, such as failure to open.

Given the limitation of previous publications with limited sample size and heterogeneity because of the grouping of patients with ruptured and nonruptured aneurysms when reporting outcomes, our cohort was divided into 2 subgroups: ruptured and nonruptured aneurysms. The primary outcomes of this study included the following: (1) effectiveness, defined as the rate of near-complete occlusion (RRI + RII) in intracranial aneurysms treated with the SVB; (2) safety, defined as the rate of morbidity procedure–related complications (eg, the incidence of major stroke [ischemic or hemorrhagic] in the territory supplied by the treated artery and neurological death associated with the procedure). Additional outcomes included rates of complete aneurysm occlusion at follow-up, overall procedure-related complications, and mortality; procedure-related or delayed aneurysm rupture; and technical challenges included device shortening, angioplasty, and additional stent deployment. Additional outcomes included aneurysm rupture, mortality, and other complications.

The SVB is a FD designed specifically for deployment using a 0.017″ microcatheter, facilitating navigation through challenging and distal vessel anatomies. This design innovation allows the treatment of lesions previously considered untreatable by endovascular methods. The SVB is indicated for use in intracranial vessels with diameters ranging from 1.5 mm to 3.5 mm. The device is available commercially in the EU (Conformité Européenne mark on 12 May 2018) and in Canada (License Amendment on 15 March 2022). Since SVB has not yet gained commercial approval in the United States, all cases performed in the United States were approved through the Food and Drug Administration Expanded Access to Medical Device pathway. The procedures were performed by experienced neurointerventionalists under either general anesthesia or local anesthesia with conscious sedation, using femoral or radial artery access. In elective cases, dual-antiplatelet therapy was initiated according to each institution's standard protocols, typically 5-7 days before the procedure. Antiplatelet responsiveness testing (eg, VerifyNow Accumetrics) was used when available. For urgent cases, an immediate antiplatelet loading dose was administered, or an intravenous antiplatelet agent (eg, cangrelor, eptifibatide) was used. The antiplatelet regimen was maintained for a minimum of 3 months postprocedure to ensure vessel patency and minimize thromboembolic risks.

Categorical variables are presented as n and percentage, and continuous variables are presented as median with standard deviation. The Pearson χ2 test was used to compare categorical variables (eg, morbidity, mortality, complete occlusion, near-complete occlusion, presence of residual aneurysm, and technical success). Independent t-Test was used to compare continuous variables (eg, age, aneurysm neck, width, height, proximal and distal parent vessel diameters); P-values <0.05 were considered statistically significant.

A total of 95 patients were included in this study after being treated using the SVB device, and a total of 97 aneurysms were treated. Most patients were female (68.1%), and the age ranged from 13 to 84 years (mean 55.3 years [SD 14.84]). The incidence of hypertension, diabetes, and coronary disease were 61.4%, 4.8%, and 3.7%, respectively. A total of 11% of the patients had a history of previous stroke, and 37.4% had a history of smoking. A total of 31% of aneurysms presented as ruptured status at admission. Regarding aneurysm location, 58.3% were in the anterior circulation. The posterior inferior cerebellar artery was the most frequent location for aneurysm presentation, encompassing 24% of the aneurysms from our cohort. Saccular aneurysms represented 57.4% of the cases, followed by fusiform, dissecting, and blister aneurysms, presenting 18.1%, 12.8%, and 11.7% of the cases, respectively. The mean size of the aneurysm neck was 3.60 mm, with aneurysm width of 7.72 mm and height of 6.10 mm. The proximal parent vessel presented a mean diameter of 2.83 mm and the distal parent vessel a mean diameter of 2.48 mm (Table 1). Demographics and Aneurysm Information ACA, anterior cerebral artery; MCA, middle cerebral artery; mRS, modified Rankin Scale; PICA, posterior inferior cerebellar artery.

A total of 31% of aneurysms presented as ruptured status at admission. Regarding aneurysm location, 58.3% were in the anterior circulation. The posterior inferior cerebellar artery was the most frequent location for aneurysm presentation, encompassing 24% of the aneurysms from our cohort. Saccular aneurysms represented 57.4% of the cases, followed by fusiform, dissecting, and blister aneurysms, presenting 18.1%, 12.8%, and 11.7% of the cases, respectively. The mean size of the aneurysm neck was 3.60 mm, with aneurysm width of 7.72 mm and height of 6.10 mm. The proximal parent vessel presented a mean diameter of 2.83 mm and the distal parent vessel a mean diameter of 2.48 mm (Table 1). Demographics and Aneurysm Information ACA, anterior cerebral artery; MCA, middle cerebral artery; mRS, modified Rankin Scale; PICA, posterior inferior cerebellar artery. A total of 45% of the cases had a previous treatment of the index aneurysm. Among these cases, 69.4% were treated with coiling, 16.7% with clipping, 8.3% with stent-assisted coiling, 2.8% with flow diverters, and 2.8% with Woven EndoBridge devices. The size of the SVB devices deployed ranged from 2.25 × 10 mm to 3.25 × 30 mm. In the index treatment, more than 1 SVB was deployed in 14.9% of cases. Considering this aspect, more than 1 SVB was required in 24.1% of the ruptured aneurysm cases and 10.8% of the unruptured cases. Adjunct coiling was performed in 22.9% of cases, whereas adjunct stenting and angioplasty were required in 7.1% and 10.4% of the cases, respectively. There was a trend of increased use of multiple SVB devices in ruptured cases, at 24.1% compared with 10.8% in unruptured cases. The same scenario was found regarding angioplasty; this was required in 20% of the ruptured aneurysms and 6.1% of the unruptured aneurysms. Adjuvant use of stent was performed in 4 cases, and the Leo Baby (Balt) and Neuroform Atlas (Styker) stents were used in this scenario (Table 2).

ed with 10.8% in unruptured cases. The same scenario was found regarding angioplasty; this was required in 20% of the ruptured aneurysms and 6.1% of the unruptured aneurysms. Adjuvant use of stent was performed in 4 cases, and the Leo Baby (Balt) and Neuroform Atlas (Styker) stents were used in this scenario (Table 2). Procedure Characteristics FD, flow diverter; SVB, Silk Vista Baby; WEB, Woven EndoBridge. The overall complication incidence was 13.8%, with most of them occurring in ruptured aneurysm cases. This group presented complications in 24.1% of the cases, whereas the unruptured cases presented a 9.2% overall complication rate. Intraprocedural complications were 4.3%, whereas periprocedural complications were 9.6%. Ruptured aneurysms had 6.9% intraprocedural complications and 17.2% periprocedural complications, whereas unruptured aneurysms presented 3.1% of intraprocedural and 6.2% of periprocedural complications. Ischemic thromboembolic complications were present in 17.2% of ruptured aneurysms and 6.2% of unruptured aneurysms. Among these cases, 44.4% were symptomatic, and 55.6% were asymptomatic.

riprocedural complications, whereas unruptured aneurysms presented 3.1% of intraprocedural and 6.2% of periprocedural complications. Ischemic thromboembolic complications were present in 17.2% of ruptured aneurysms and 6.2% of unruptured aneurysms. Among these cases, 44.4% were symptomatic, and 55.6% were asymptomatic. Intraprocedural complications included a case of complete occlusion of the anterior inferior cerebellar artery caused by a severe kinking proximal to the device, demanding the deployment of a second partially overlapping SVB, a case of dissection at the origin of the posterior inferior cerebellar artery, and an aneurysm rupture. No morbidity cases were found neither in ruptured nor in unruptured cases. Two cases (2.1%) of mortality occurred within our cohort, 1 in the ruptured and the other in the unruptured aneurysms group (Table 3). One death was related to the intraprocedural rupture of the anterior communicating artery, which required bilateral anterior cerebral artery sacrifice. This procedure was performed immediately after the SVB deployment, and the ruptured point was secured with coils, 23 days after the procedure brain death was declared. The second death was assessed as not directly related to the procedure; a patient with poor neurological condition at admission (Glasgow Coma Scale 4) demonstrated delayed cerebral ischemia and died from sepsis 20 days after hospital admission. Safety, Complications, Mortality, Clinical, and Effectiveness Outcomes mRS, modified Rankin Scale; RR, Raymond-Roy. There were no morbidity cases. Mean time of follow-up 14.94 months.

Intraprocedural complications included a case of complete occlusion of the anterior inferior cerebellar artery caused by a severe kinking proximal to the device, demanding the deployment of a second partially overlapping SVB, a case of dissection at the origin of the posterior inferior cerebellar artery, and an aneurysm rupture. No morbidity cases were found neither in ruptured nor in unruptured cases. Two cases (2.1%) of mortality occurred within our cohort, 1 in the ruptured and the other in the unruptured aneurysms group (Table 3). One death was related to the intraprocedural rupture of the anterior communicating artery, which required bilateral anterior cerebral artery sacrifice. This procedure was performed immediately after the SVB deployment, and the ruptured point was secured with coils, 23 days after the procedure brain death was declared. The second death was assessed as not directly related to the procedure; a patient with poor neurological condition at admission (Glasgow Coma Scale 4) demonstrated delayed cerebral ischemia and died from sepsis 20 days after hospital admission. Safety, Complications, Mortality, Clinical, and Effectiveness Outcomes mRS, modified Rankin Scale; RR, Raymond-Roy. There were no morbidity cases. Mean time of follow-up 14.94 months. A total of 87% of patients presented modified Rankin Scale (mRS) equal to or lower than 2 at discharge, with 79.3% of ruptured cases and 90.6% of unruptured cases falling within this score range. A total of 13% of patients had a mRS score of 3 or higher. This included 20.7% of patients with ruptured cases and 9.4% with unruptured cases. No differences were observed in mRS values from discharge to the last follow-up. The mean time of follow-up was 14.94 months, with magnetic resonance angiography (MRA) being the most used imaging modality. Regarding the occlusion rate, complete occlusion (RR 1) was observed in 56.5% of the patients, 71.43% of ruptured cases, and 50% of unruptured, demonstrating a trend of higher occlusion rate among the ruptured cases. The presence of side branches was statistically significantly related to a higher incidence of residual aneurysms (P-value 0.011, 95% CI: 1.305-8.641). Overall, the near-complete occlusion (RR1 + RR2) rate was 76.1%, corresponding to 81.14% and 73.43% for ruptured and unruptured aneurysms, respectively. Residual aneurysms (RR2 + RR3) were present in 43.47% of cases, presenting an incidence of 28.57% in the ruptured cases and 50% in the unruptured ones. A significant difference was observed in the technical success rate, with the unruptured cases presenting an optimal rate of 100% vs 93.1% (P-value 0.032, 95% CI: 0.218-0.406) success rate in the ruptured cases (Table 3; Figure).

s, presenting an incidence of 28.57% in the ruptured cases and 50% in the unruptured ones. A significant difference was observed in the technical success rate, with the unruptured cases presenting an optimal rate of 100% vs 93.1% (P-value 0.032, 95% CI: 0.218-0.406) success rate in the ruptured cases (Table 3; Figure). A, DSA and volume rendering of 3D-DSA. B, demonstrating an aneurysm at the origin of the PICA. C, Postdeployment-contrasted cone beam CT demonstrating good apposition of the SVB device. D, 6-month DSA follow-up demonstrating complete occlusion (Raymond-Roy 1) of the PICA aneurysm. E, DSA and volume rendered 3D-DSA. F, demonstrating a fusiform aneurysm of the PICA. G, 1-year DSA follow-up demonstrating complete occlusion (Raymond-Roy 1) of the PICA aneurysm. H, 1-year unsubtracted angiography demonstrating good apposition of the SVB device. I, DSA and volume rendered 3D-DSA. J, demonstrating a recurrent anterior communicating artery aneurysm. Postdeployment cone beam CT (K) and DSA (L) demonstrating good apposition of the SVB device. 3D, 3-dimensional; CT, computed tomography; DSA, digital subtraction angiography; PICA, posterior inferior cerebellar artery; SVB, Silk Vista Baby.

A total of 45% of the cases had a previous treatment of the index aneurysm. Among these cases, 69.4% were treated with coiling, 16.7% with clipping, 8.3% with stent-assisted coiling, 2.8% with flow diverters, and 2.8% with Woven EndoBridge devices. The size of the SVB devices deployed ranged from 2.25 × 10 mm to 3.25 × 30 mm. In the index treatment, more than 1 SVB was deployed in 14.9% of cases. Considering this aspect, more than 1 SVB was required in 24.1% of the ruptured aneurysm cases and 10.8% of the unruptured cases. Adjunct coiling was performed in 22.9% of cases, whereas adjunct stenting and angioplasty were required in 7.1% and 10.4% of the cases, respectively. There was a trend of increased use of multiple SVB devices in ruptured cases, at 24.1% compared with 10.8% in unruptured cases. The same scenario was found regarding angioplasty; this was required in 20% of the ruptured aneurysms and 6.1% of the unruptured aneurysms. Adjuvant use of stent was performed in 4 cases, and the Leo Baby (Balt) and Neuroform Atlas (Styker) stents were used in this scenario (Table 2). Procedure Characteristics FD, flow diverter; SVB, Silk Vista Baby; WEB, Woven EndoBridge.

The overall complication incidence was 13.8%, with most of them occurring in ruptured aneurysm cases. This group presented complications in 24.1% of the cases, whereas the unruptured cases presented a 9.2% overall complication rate. Intraprocedural complications were 4.3%, whereas periprocedural complications were 9.6%. Ruptured aneurysms had 6.9% intraprocedural complications and 17.2% periprocedural complications, whereas unruptured aneurysms presented 3.1% of intraprocedural and 6.2% of periprocedural complications. Ischemic thromboembolic complications were present in 17.2% of ruptured aneurysms and 6.2% of unruptured aneurysms. Among these cases, 44.4% were symptomatic, and 55.6% were asymptomatic.

A total of 87% of patients presented modified Rankin Scale (mRS) equal to or lower than 2 at discharge, with 79.3% of ruptured cases and 90.6% of unruptured cases falling within this score range. A total of 13% of patients had a mRS score of 3 or higher. This included 20.7% of patients with ruptured cases and 9.4% with unruptured cases. No differences were observed in mRS values from discharge to the last follow-up. The mean time of follow-up was 14.94 months, with magnetic resonance angiography (MRA) being the most used imaging modality. Regarding the occlusion rate, complete occlusion (RR 1) was observed in 56.5% of the patients, 71.43% of ruptured cases, and 50% of unruptured, demonstrating a trend of higher occlusion rate among the ruptured cases. The presence of side branches was statistically significantly related to a higher incidence of residual aneurysms (P-value 0.011, 95% CI: 1.305-8.641). Overall, the near-complete occlusion (RR1 + RR2) rate was 76.1%, corresponding to 81.14% and 73.43% for ruptured and unruptured aneurysms, respectively. Residual aneurysms (RR2 + RR3) were present in 43.47% of cases, presenting an incidence of 28.57% in the ruptured cases and 50% in the unruptured ones. A significant difference was observed in the technical success rate, with the unruptured cases presenting an optimal rate of 100% vs 93.1% (P-value 0.032, 95% CI: 0.218-0.406) success rate in the ruptured cases (Table 3; Figure).

To the best of our knowledge, this is the largest combined experience of SVB published alongside the longest mean follow-up. The device demonstrated similar occlusion and morbi-mortality rates compared with the previous series. At 15-month follow-up, occlusion rates were 56% complete occlusion rates and 76% near-complete occlusion rates, specifically in the unruptured aneurysm group complete rate of complete occlusion was 50%. Since SVB received the Conformité Européenne mark in 2018, multiple studies have reported occlusion in the early-term follow-up angiographic results for SVB. The complete occlusion rate in these reports varied from 57.1% to 76.9%, and the near-complete occlusion rate ranged from 69.6% to 92.3%.3,7,8 Raymond-Roy scale is not ideal for FD aneurysm assessment, in special when branches are involved. The concept of stable remodeling in aneurysms harboring branches has been described and can explain the lower rate of complete aneurysm occlusion when compared with side wall aneurysms.9

te ranged from 69.6% to 92.3%.3,7,8 Raymond-Roy scale is not ideal for FD aneurysm assessment, in special when branches are involved. The concept of stable remodeling in aneurysms harboring branches has been described and can explain the lower rate of complete aneurysm occlusion when compared with side wall aneurysms.9 This heterogeneity in the occlusion rate could be attributed to factors such as sample size, variability in aneurysm characteristics, differences in the location, presence of incorporated branches on treated aneurysms, treatment of bifurcation lesions, and definition of outcomes, as well as imaging modality used for post-treatment assessment. This variability was demonstrated in our series, where there was a high utilization of MRA for follow-up and a high incidence of complex aneurysms (rupture and fusiform). Interestingly, unruptured aneurysms presented a higher incidence of fusiform aneurysms compared with ruptured cases. As a result, the occlusion rates were notably lower in the cases of unruptured fusiform aneurysms.10 The rates of adjunctive coiling (22.7%), stenting (7.1%), and angioplasty (10.3%) in our series were consistent with previous studies using SVB.3,7,8,11

gher incidence of fusiform aneurysms compared with ruptured cases. As a result, the occlusion rates were notably lower in the cases of unruptured fusiform aneurysms.10 The rates of adjunctive coiling (22.7%), stenting (7.1%), and angioplasty (10.3%) in our series were consistent with previous studies using SVB.3,7,8,11 Previous FD studies have shown that the occlusion rate, inherent to FD treatment modality, increases most significantly within the first 12 months with some further progression of occlusion or stabilization beyond that.12,13 However, as previously mentioned, intrinsic aneurysm characteristics significantly influence occlusion rates. Among these factors, branches originating from the aneurysm can result in a hemodynamic compensation phenomenon that interferes with aneurysm occlusion.11,14 This phenomenon was reflected in our series, where 59% of aneurysms had branches originating from the aneurysm, which was related to a higher incidence of residual aneurysms. Similarly, Rodríguez-Fernández et al11 reported a comparable rate of 64%, with a 66% complete occlusion rate observed at the 12-month follow-up. In our cohort, we found that among the unruptured cases with incomplete occlusion, the incidence of side branches was 75%.

related to a higher incidence of residual aneurysms. Similarly, Rodríguez-Fernández et al11 reported a comparable rate of 64%, with a 66% complete occlusion rate observed at the 12-month follow-up. In our cohort, we found that among the unruptured cases with incomplete occlusion, the incidence of side branches was 75%. The present series had 97.9% technical success, which matches a systematic review by Hanel et al,5 which reported 98.8% technical success among various studies. This high technical success rate has been consistently reported because of the device being delivered using a 0.017-inch catheter, which enhances navigability. Its design allows navigation through tortuous anatomy in vessels smaller than 3.5 mm.1 This high technical success rate has been shared by FRED Jr. (Microvention) and the p48 movable wire (MW) flow-diverting device (Phenox GmbH).

se of the device being delivered using a 0.017-inch catheter, which enhances navigability. Its design allows navigation through tortuous anatomy in vessels smaller than 3.5 mm.1 This high technical success rate has been shared by FRED Jr. (Microvention) and the p48 movable wire (MW) flow-diverting device (Phenox GmbH). In contrast to the SVB, FRED Jr. and the p48 MW FD were designed to be delivered using a 0.021-inch microcatheter. Despite this difference in the delivery system, FRED Jr. reported a complete occlusion rate of 70% at 6 months and a near-complete occlusion rate of 77%, whereas the p48 MW showed complete occlusion rates of 37.5% and near-complete occlusion of 93.1%, both achieving high delivery success.15,16 Hohenstatt et al17 observed an improvement in the occlusion rate over time after treating 68 patients with 84 aneurysms using either FRED or FRED Jr., with adjunctive coiling in 21% of cases. These authors reported a complete occlusion of 77.4% and near-complete occlusion of 97.8% at 2-year follow-up, with a subsequent complete occlusion of 84.9% and near-complete occlusion of 100% after 5-year follow-up. On the other hand, a literature review by Vivanco-Suarez et al.18 reported that the p48 MW device, with adjunctive coiling in 4% of cases, demonstrated a 67% complete angiographic occlusion rate at varying follow-up times ranging from 2 to 14.5 months in 156 patients with 156 aneurysms. Based on these results, the paradigm that stiff FDs were incompatible with small (<2.5 mm) or distal arteries aneurysms treatment changed, with the SVB device now proportioning a treatment option to previously untreatable aneurysms.19

ing follow-up times ranging from 2 to 14.5 months in 156 patients with 156 aneurysms. Based on these results, the paradigm that stiff FDs were incompatible with small (<2.5 mm) or distal arteries aneurysms treatment changed, with the SVB device now proportioning a treatment option to previously untreatable aneurysms.19 Regarding safety, the multicenter study using FRED Jr. 15 reported an incidence of ischemic complications of 12% (5/42). Symptomatic ischemic complications occurred in 7% (3/42) of cases: 1 major stroke resulting in a disabling condition, 1 minor stroke with complete recovery at discharge, and 1 transient ischemic attack. The remaining 5% (2/42) were asymptomatic, completely reversible side-branch occlusions. Notably, no hemorrhagic complications were reported. By contrast, a meta-analysis by El-Naamani et al20 reported 5.3% stroke rate, 0.4% hemorrhagic event rate, and 0% mortality at midterm follow-up. Alternatively, the overall complication rate for the p48 MW FD was 3%, and the mortality rate was 2%.18

ranch occlusions. Notably, no hemorrhagic complications were reported. By contrast, a meta-analysis by El-Naamani et al20 reported 5.3% stroke rate, 0.4% hemorrhagic event rate, and 0% mortality at midterm follow-up. Alternatively, the overall complication rate for the p48 MW FD was 3%, and the mortality rate was 2%.18 Our study demonstrated an overall complication rate of 13.8%. Intraprocedural complications occurred in 4.3% of cases, whereas periprocedural complications were observed in 9.6%, with a rate of periprocedural complication in unruptured aneurysms of 6.2%. The incidence of complications was higher in ruptured cases (17.2%). Interestingly, the only treatment-related mortality occurred in an unruptured case. Previous studies have reported procedural complication rates ranging from 0% to 15.9% and neurological mortality rates from 0% to 3.3%.3,7,8,11 Our study included a higher proportion of acute and previously ruptured aneurysms compared with similar studies3,11 while maintaining a similar range of overall complications and neurological mortality rates, including comparable periprocedural complication rates of 5.6% and 5.9%.21,22 The main limitations are the retrospective design, operator self-adjudication, interobserver variability in the RR classification, and its limitation accounting for flow-diverting devices. Most follow-ups used MRA, risking aneurysm occlusion overestimation.

The main limitations are the retrospective design, operator self-adjudication, interobserver variability in the RR classification, and its limitation accounting for flow-diverting devices. Most follow-ups used MRA, risking aneurysm occlusion overestimation.

Our case series demonstrated the efficacy of the SVB device with high technical success rates. The occlusion rates for ruptured cases are comparable with those of other FDs. However, the rates are lower for unruptured cases. This discrepancy is likely due to the characteristics of the aneurysms, particularly in the presence of side branches in bifurcation lesions. The safety profile remained comparable in the unruptured group, whereas the ruptured group exhibited a higher overall complication rate. Importantly, morbidity and mortality rates were consistent with those reported in other FDs. These findings highlight the utility of SVB for distally located aneurysms and underscore the need for prospective studies to better address the inherent limitation of the current one.