Stent plus balloon-assisted coiling with low-profile braided stents in the treatment of complex wide-necked intracranial bifurcation aneurysms

Abstract

Introduction

Wide-necked bifurcation aneurysms pose significant challenges for endovascular treatment. A recent innovation, the stent plus balloon-assisted coiling technique, combines a stent and a balloon to address these aneurysms effectively.

Purpose

To evaluate the safety and efficacy of the stent plus balloon-assisted coiling for the treatment of wide-necked bifurcation aneurysms.

Methods

We conducted a retrospective review of our endovascular database to identify patients who were treated with this technique and had a satisfactory angiographic follow-up of at least 24 months. Technical success, initial clinical and angiographic outcomes, procedural complications, and follow-up results were analyzed. Angiographic and clinical outcomes were assessed using Modified Raymond-Roy Classification and Modified Rankin Scale, respectively.

Results

Our study included 37 aneurysms in 36 patients (26 females) with a mean age of 56.6 years. Mean aneurysm and neck sizes were 7.3 ± 3.5 mm and 3.7 ± 1.0 mm, respectively. Technical success reached 97.2%, with an immediate occlusion rate of 65.7%. At a mean follow-up of 36.5 ± 9.7 months, final angiographic follow-up showed a 91.9% complete occlusion rate. Three aneurysms did not achieve complete occlusion; however, none required retreatment. Complications developed in 32.4% of the procedures. Mortality and morbidity rates were 5.4% and 2.7%, respectively. A good clinical outcome was observed in 91.9% of patients.

Conclusion

Our results showed that stent plus balloon-assisted coiling technique allows good angiographic outcomes for wide-necked bifurcation aneurysms. However, overall complication rate is high. Subgroup analysis indicated promising safety and efficacy for MCA bifurcation aneurysms, suggesting this technique could be a valuable option for select aneurysms.

Introduction

Intracranial wide-necked bifurcation aneurysms (WNBAs) present significant challenges for endovascular treatments due to their broad neck and neck-associated daughter branches. Therefore, the primary goal of treatment is to achieve complete occlusion while preserving the patency of the neck-associated branches. To overcome these challenges, several techniques, such as double-balloon remodeling, dual stent-assisted coiling (DSAC), flow diverters, neck bridging, and intrasaccular devices, have been developed.^1,2

The stent plus balloon-assisted coiling (SBAC) technique was recently introduced for treating WNBAs. ³ This technique utilizes a partially deployed stent and a temporarily inflated balloon to protect the bifurcation branches. The stent and balloon also remodel the neck of the aneurysm for safe coiling (Figure 1). After coiling, the balloon is removed, and the stent is fully deployed. Essentially, this technique involves implanting just a single stent in the parent vessel. Thus, the SBAC technique provides a technically straightforward and cost-effective treatment alternative to DSAC for challenging complex WNBAs.

Figure 1.

The illustration demonstrates the stent plus balloon-assisted coiling technique: the stent and balloon protect both bifurcation branches and remodel the aneurysm neck. Additionally, a microcatheter is visible inside the aneurysm sac for coil delivery. © Kadir Kabadayi and Luiza Rangel Agostinho, used with permission. All rights reserved.

In the SBAC technique, both low-profile braided and laser-cut stents are options. However, our study exclusively utilized braided stents, ensuring uniform data and emphasizing the technique’s efficacy. This technique eliminates the need for a microcatheter to cross stent struts, making braided stents a fitting choice. Although their increased metal coverage and reduced cell size might raise the risk of dislocation during crossing maneuvers, the SBAC technique obviates this drawback. Braided stents, with their enhanced coil support and flow diversion capabilities, effectively contribute to aneurysm occlusion. ⁴ Their closed-cell design further allows for in-procedure reshaping and repositioning. ⁵ These attributes highlight the aptness of braided stents for the SBAC technique.

The SBAC technique has been proposed as a promising alternative for WNBAs. However, comprehensive data regarding its efficacy across different aneurysm localizations and sizes is very limited in the literature. In this retrospective study, we aimed to assess the initial and long-term angiographic and clinical outcomes of WNBAs treated using the SBAC technique with low-profile braided stents. Additionally, we evaluated the influence of aneurysm characteristics on these outcomes.

Methods

Population and study design

This single-center, retrospective study was conducted after receiving approval from the institutional ethics committee. Our institution started service in 2018. We reviewed our database from 2018 to December 2021 to identify patients with intracranial complex WNBAs treated with the SBAC technique using a low-profile braided stent. This period was chosen to filter patients who had a satisfactory follow-up of at least 24 months. Complex wide neck bifurcation aneurysms were defined as aneurysms with a neck diameter >4 mm or a dome-to-neck ratio <2 and having a neck associated with more than one daughter branch. We collected data on patient demographics, presenting symptoms, and aneurysm characteristics, including location and size. We also gathered details on the technical aspects of the endovascular procedures, any complications, and both clinical and angiographic outcomes. These outcomes were based on neurological evaluations and both invasive and non-invasive angiographic assessments. Given the retrospective nature of the study, patient consent was not sought.

Preprocedural evaluation

All aneurysms included in the study were scheduled for elective treatment. Two to 6 weeks prior to endovascular treatment, patients underwent diagnostic DSA. 2D and 3D rotational images were evaluated. This served as the gold standard for diagnosis and also assisted in treatment planning. Patients were prescribed dual antiplatelet therapy (DAPT) of 75 mg clopidogrel and 100 mg aspirin daily, starting 2 weeks before the procedure. Platelet aggregation inhibition was assessed using the Multiplate Analyzer [Roche, Basel, Switzerland] 7–10 days after commencing the therapy. Patients who responded inadequately to clopidogrel were switched to ticagrelor (2 × 90 mg/day).

Endovascular procedure

All procedures were performed under general anesthesia. Arterial access was achieved under ultrasound guidance with the Seldinger technique from either single or both common femoral arteries. Intraprocedural anticoagulation was initiated immediately after the insertion of the femoral introducer sheath with a bolus dose of 5000 IU, followed by 1000 IU heparin per hour. The activated clotting time was maintained within a target range of 250–300 s. For anterior system aneurysms, Neuron Max 088 [Penumbra, Alameda, California] long sheath was placed at the ICA distal cervical segment, and for posterior system aneurysms, it was positioned at the vertebral artery V4 segment level. A pre-nimodipinized saline flush bag, with 15 mL (of 10 mg/50 mL concentration) per 1000 mL, is used for the Neuron Max guiding sheath to prevent vasospasm and thrombus formation during the procedure. Then, both the bifurcation branches and the aneurysm sac were catheterized using distinct microcatheters, advanced over a soft tip 0.014-inch microwire. First, the balloon-protected branch was catheterized using either a single-lumen balloon microcatheter (HyperForm [Medtronic, Dublin, Ireland]) or a dual-lumen balloon microcatheter (Scepter XC [MicroVention, Tustin, California] or Eclipse 2L [Balt, Montmorency, France]). Next, the aneurysm sac was catheterized, and the coil catheter (Echelon-10) was jailed. Lastly, the bifurcation branch, which was more incorporated into the neck of the aneurysm, was catheterized using either a 0.017-inch microcatheter, Headway 17 [MicroVention/Terumo, Tustin, California] or the Echelon-10 [Medtronic, Dublin, Ireland] for stent delivery. Coiling was initiated after the stent was partially deployed and the balloon temporarily inflated. Once complete sac embolization was achieved, or it was determined that no further coils could be safely deployed, the balloon was removed, and the stent was then fully deployed. At the end of the procedure, immediate control DSA images were acquired to assess the degree of aneurysm occlusion, the patency of the stent, and the intracranial arteries in the territory of the target artery. The procedure then concluded, and the patient was extubated. Upon regaining consciousness on the Angio table, an immediate neurological examination was performed. With normal findings, the patient was moved to the Angio unit’s observation room. A 24-hour heparin infusion was initiated, targeting aPTT levels 2–2.5 times the norm. The patient had periodic neurological assessments for 2 h in the observation room and then transferred to the neurointensive care unit. The femoral sheath was retained overnight and removed the following day. A vascular closure device, AngioSeal [Terumo, Somerset, NJ, USA], was subsequently utilized. Following a neurological examination with normal findings, the patient was transferred to the ward and discharged after 6 h. DAPT was maintained for 6 months, followed by aspirin only thereafter.

Angiographic follow-up

The Modified Raymond-Roy Classification (mRRC) was utilized to determine the degree of aneurysm occlusion in immediate post-procedural and follow-up angiographic images. ⁶ The mRRC 1 signified complete aneurysm occlusion; mRRC 2, 3a, and 3b indicated incomplete occlusions. An mRRC score of 1 or 2 denoted a good angiographic outcome, while scores of 3a and 3b indicated a poor angiographic outcome. During follow-up imaging, an upgrade in mRRC score (from 3b, 3a, 2) to mRRC score 1, indicated progressive thrombosis of the aneurysm, while a deterioration in mRRC score signified recanalization. Follow-up invasive and non-invasive angiographies were performed to assess the degree of aneurysm occlusion and stent patency. The first MRA control was performed 3 months after the procedure, and the first DSA control was performed 6 months after the procedure, followed by a second DSA control after 12 months. Thereafter, patients underwent annual MRA follow-ups.

Clinical follow-up

Before the procedure, immediately afterward, at discharge, and during clinical follow-ups, the modified Rankin Scale (mRS) was used to assess the neurological status of patients. Clinical follow-up began in the second week following discharge. Subsequent neurological assessments were conducted during angiographic follow-ups. Any symptoms or clinical manifestations that arose during post-procedural follow-ups were documented. Periprocedural complications were defined as complications that occurred during the endovascular operation or within 14 days following the procedure. Complications identified after these 14 days were categorized as delayed complications. ³ A good clinical outcome was defined as an mRS score of 0 or 1. Permanent neurological deficit was defined as mRS scores ranging from 2 to 5, and mortality was defined as an mRS score of 6.

Statistical analysis

Data were analyzed using IBM SPSS Statistics 22 (SPSS, Inc., Chicago, IL, USA) software. The Shapiro–Wilk test was used to assess normality. For data that were normally distributed, the student’s t-test was employed to compare mean values. For data that were not normally distributed, the Mann–Whitney U test was used. Categorical data were analyzed using the chi-square test, with the Fisher’s exact test used where appropriate. Statistical significance was set at p < .05. The Bonferroni correction was applied when necessary.

Results

Patient demographics and aneurysm characteristics

During the search period, 504 intracranial aneurysms in 424 patients were treated. Of these, 54 complex WNBAs in 53 patients were managed with the SBAC technique. Sixteen aneurysms were excluded due to incomplete imaging follow-ups, and one patient was excluded due to treatment with a laser-cut stent. Of the 53 patients, 36 were included in the study, representing 37 aneurysms. One patient presented with bilateral MCA bifurcation aneurysms, which were treated using the SBAC technique in two separate sessions, with an interval of 1 year. The mean age of the patients was 56.6 ± 11.4 years, ranging from 27 to 78 years. Of these patients, 26 (70.2%) were female (Table 1). The majority of aneurysms were discovered incidentally. Thirty-four out of the 37 aneurysms had not undergone prior treatment. Three aneurysms (8.1%) had previously undergone treatment with balloon-assisted coiling due to SAH but had shown recurrence. Furthermore, six patients had been treated—either endovascularly or surgically—for another aneurysm in the past.

Table 1.

Patient demographics and aneurysm characteristics.

The mean age	56.7 ± 11.4
Sex
Female	26 (70.2%)
Male	11 (29.7%)
Comorbidities
Hypertension	12 (32.4%)
Diabetes mellitus	5 (13.5%)
Hypothyroidism	4 (10.8%)
Asthma	2 (5.4%)
Clinical finding
Incidental discovery	33
Recurrence	3
Compression	1
The mean aneurysm size (mm)	7.3 ± 3.5
Small (<7 mm)	20 (54.0%)
Medium (7–15 mm)	15 (40.5%)
Large (>15 mm)	2 (5.4%)
Aneurysm location	Number (%)
MCA bifurcation	22 (59.4%)
The mean aneurysm size (mm)	5.6 ± 2.0
The mean neck width (mm)	3.2 ± 0.7
AcomA	10 (27.0%)
The mean aneurysm size (mm)	8.6 ± 3.9
The mean neck width (mm)	4.1 ± 0.9
Basilar tip	3 (8.1%)
The mean aneurysm size (mm)	9.6 ± 1.9
The mean neck width (mm)	5.6 ± 0.8
ICA bifurcation	2 (5.4%)
The mean aneurysm size (mm)	13.5 ± 3.5
The mean neck width (mm)	4.8 ± 0.7

AcomA = Anterior communicating artery, MCA = Middle cerebral artery, ICA = Internal carotid artery.

In terms of location, 22 (59.4%) of the 37 aneurysms were at the MCA bifurcation, 10 (27.0%) at the AcomA. The mean aneurysm size was 7.3 ± 3.5 mm (range: 3.8-16 mm), and the mean neck width was 3.7 ± 1.0 mm (range: 2.0-6.5 mm). Neck width was ≥4 mm in 16 of 37 aneurysms; all aneurysms with a neck width <4 mm, and most of the aneurysms with a neck width ≥4 mm had a dome-to-neck ratio <2 (34/37). Aneurysm characteristics varied by location, as detailed in Table 1. The baseline mRS score was 0 for 34 patients (91.9%) and 1 for 3 patients (8.1%), attributable to age-related factors or previous SAH.

Immediate angiographic outcomes

The technical success rate of the treatment, in terms of preserving the patency of neck-associated vessels while allowing the coil embolization of the aneurysm sac, was 97.2%. A low-profile braided stent was fully deployed in 34 procedures (91.8%). The mean diameter of neck-associated branches, as well as the details of used stents and balloon catheters, are provided in Table 2. The immediate post-procedural control DSA revealed complete occlusion (mRRC 1) in 64.9% (24/37) of the aneurysms. Additionally, 16.2% (6/37) of the aneurysms scored as mRRC 2, 16.2% (6/37) as mRRC 3a, and 2.7% (1/37) as mRRC 3b. Overall, a good angiographic outcome was observed in 83.7% (31/37) of the aneurysms. Aneurysms of larger sizes (p = .037) and those with wider neck widths (p = .033) were significantly associated with poor immediate angiographic outcomes (Supplementary Table 1).

Table 2.

Mean diameters of bifurcation branches and endovascular tools.

The mean neck width (mm)	3.7 ± 1.10
The mean dome-to-neck ratio	1.5 ± 0.32
The mean diameter of parent arteries (mm)	2.6 ± 0.41
The mean diameter of stent-protected branches (mm)	2.2 ± 0.32
The mean diameter of balloon-protected branches (mm)	2.1 ± 0.26
Arterial access site
Single femoral	32 (86.4%)
Bilateral femoral	5 (13.5%)
Stents
Leo Baby (Balt)	31 (83.7%)
LVIS Jr (Microvention)	3 (8.1%)
LVIS Evo (Microvention)	3 (8.1%)
Balloon catheters
Scepter XC (Microvention)	33 (89.1%)
HyperForm (Medtronic)	2 (5.4%)
Eclipse (Balt)	2 (5.4%)
Stent fully deployed at the end of the procedure
Yes	34 (91.9%)
No	3 (8.1%)

Complications

Periprocedural complications were observed in 12 of 37 procedures (32.4%). The primary subtype of these complications was thromboembolic, comprising 6 in-stent thromboses and one distal embolus. In-stent thrombus occurred in one patient at the 1-week follow-up due to noncompliance with prescribed DAPT and in one patient at 6 h postoperatively. The remainder of the cases manifested intraoperatively. Periprocedural complications led to permanent morbidity for one patient (2.7%) and mortality in two patients (5.4%). The patient who experienced permanent neurological sequelae had a right MCA bifurcation aneurysm with a 5.3 mm sac and 3.8 mm neck. After the stent was fully deployed, an acute intraoperative partial in-stent thrombus developed. Although TICI 2b recanalization was achieved with tirofiban (0.5 mg Aggrastat diluted with 5 cc saline, bolus IV, twice at 5-minute intervals) and aspiration thrombectomy, the patient’s cranial MR revealed a right parietal cortical infarct. The patient had a clinical outcome of mRS 4 both at discharge and at the final follow-up.

Mortality was seen in two procedures involving aneurysms at AcomA, measuring 16 mm and 11 mm. In the first patient, despite an uncomplicated endovascular procedure, the patient remained unconscious post-procedure. Immediate CT imaging identified a large intraparenchymal hematoma. While the exact cause was unclear, there was a noted overresponse to intraoperative heparin, requiring reduced doses to achieve target ACT values. The anticoagulant effects of heparin were countered with protamine sulfate. A decompressive craniectomy was performed, but the patient progressed to brain death within a week in intensive care. The second patient developed an intraoperative in-stent thrombus, which was managed with aspiration thrombectomy and tirofiban (0.5 mg Aggrastat diluted with 5 cc saline, bolus IV, twice at 5-minute intervals) treatment. Intraoperative imaging showed no active bleeding. However, during postoperative follow-up, the patient developed a Fisher grade 3 SAH. While the exact cause of the SAH was undetermined, it occurred after the thromboembolic event and subsequent interventions, and the patient progressed to brain death.

The majority of periprocedural complications resulted in a good clinical outcome following prompt management (Table 3). Considering aneurysm characteristics, location, and patient demographics, we found no statistical differences between patients who developed procedural complications and those who did not (Supplementary Table 2). Patients who had poor clinical outcomes at discharge exhibited a higher dome-to-neck ratio compared to patients with good clinical outcomes at discharge. Notably, within our cohort, patients with medium to large aneurysms tended to have higher dome-to-neck-ratio (Supplementary Table 3).

Table 3.

Summary of periprocedural complications.

Age/Sex	Loc.	Sac mm	Neck mm	Baseline mRS	Event	Symptom	Management	Discharge mRS	Last mRS
54/F	AcomA	7	3.9	0	Intraoperative distal emboli	MW	2 mL IV tirofiban a	2	1
59/F	MCA	5	4	0	Partial in-stent thrombosis 1-week post-op due to non-adherence to DAPT	Hemiparesis	Aspiration mechanical thrombectomy	1	0
68/F	AcomA	14	4	0	Intraoperative partial in-stent thrombus	MW	Thrombus refractory to 4 mL IV tirofiban; stent removed post-coiling	1	0
62/F	MCA	5	3.2	0	Small temporoparietal subcortical intraparenchymal hematoma	Headache	Heparin reversed and Aspirin stopped. 2-week in-patient close follow-up	1	1
52/F	MCA	5	2.5	0	Intraoperative partial in-stent thrombus	MW	Thrombus refractory to 4 mL IV tirofiban; stent was removed post-coiling	1	0
68/F	MCA	6	3.1	0	Coil protrusion into stent interstices hindered full deployment, leading to in-stent thrombus. Retracting the stent further herniated the coil loop into the stent-protected branch	Hemiparesis	The first stent was fully retracted, followed by stabilization of the coil loop with the full deployment of another stent. Subsequently, a 2 mL IV tirofiban was administered, achieving TICI-2b recanalization	4	1
44/M	MCA	10	4.5	0	Intraoperative partial in-stent thrombus	None	2 mL IV tirofiban	0	0
52/M	AcomA	4	3.3	0	Intraoperative aneurysm rupture	Headache	Continued coiling; bleeding halted. Stent removed to avoid post-op heparin and DAPT use.	1	0
39/F	MCA	5	3	0	Stent occlusion 6h post-op	Hemiparesis	Immediate aspiration mechanical thrombectomy and 4 mL IV tirofiban -TICI 2c recanalization achieved	1	1

^a0.5 mg Aggrastat diluted with 5 cc saline, bolus IV (intravenous); Loc: Location; AcomA = Anterior communicating artery, MCA = Middle cerebral artery; MW = Mild weakness; DAPT = Dual antiplatelet; mRS = modified Rankin scale.

Angiographic follow-up

All patients in the follow-up underwent at least 2 DSA and 2 MRA examinations, with the shortest angiographic follow-up period lasting 24 months. At the final angiographic follow-up, complete occlusion was observed in 91.4% (32/35) of the aneurysms. Neck residue was noted in only one aneurysm, and overall, a good angiographic outcome was seen in 94.2% of the aneurysms. During subsequent follow-up periods, 4 aneurysms initially scored with mRRC 3a and 5 with mRRC 2 progressed to mRRC 1 occlusion (Figure 2). Notably, an AcomA aneurysm (9 mm sac, 6 mm neck) and an ICA bifurcation aneurysm (16 mm sac, 4.3 mm neck) displayed mRRC 3b and mRRC 3a occlusion scores, respectively, from immediate post-treatment to final angiographic follow-up. The sizes of these two aneurysms remained stable, and neither required retreatment.

Figure 2.

Intraprocedural and follow-up DSA images of a 40-year-old male patient with a right middle cerebral artery (MCA) bifurcation aneurysm. (a and d), Anterior-posterior and lateral DSA images demonstrate a 6 mm saccular aneurysm (arrows) with a 3.8 mm neck that incorporates both MCA trunks. (b), In the intraprocedural image, the white arrow indicates the balloon catheter in the upper MCA trunk, and the dashed arrows show the partially deployed 2.5 × 25 mm Leo Baby stent (Balt, Montmorency, France) in the inferior trunk. The black arrow highlights the coils in the aneurysm used to jail the microcatheter. (c), In the lateral intraprocedural image just before the coiling process, the white arrow shows the inflated balloon, and the dashed arrows indicate the partially deployed stent extending from the inferior trunk to the right MCA. The black arrow highlights the jailed microcatheter in the sac of the aneurysm. (e), Immediate postprocedural DSA image shows the stable coil mesh and the white arrow shows contrast within the coil interstices (mRRC 3a occlusion). (f), 1-year follow-up DSA image, the white arrow shows complete aneurysm occlusion (mRRC 1).

At the final follow-up, the location of the aneurysm showed a significant difference between completely occluded and incompletely occluded aneurysms (p = .034). Specifically, the MCA bifurcation was more prevalent among completely occluded aneurysms, while the ICA bifurcation was more common among incompletely occluded aneurysms (Supplementary Table 4). Furthermore, larger aneurysms (p = .024) and those with wider neck widths (p = .049) were significantly associated with poor angiographic outcomes (Supplementary Table 1).

Subgroup analyses based on aneurysm location and size showed that small aneurysms (<7 mm) achieved 100% good angiographic outcomes (19/20 mRRC1, 1/20 mRRC2) with a 2.7% morbidity rate (1/20) and no mortality at the last follow-up. MCA bifurcation aneurysms displayed a 100% complete occlusion rate (22/22) with a 2.7% morbidity rate (1/22) and no mortality. However, AcomA aneurysms had a 20% mortality rate (2/10) and no morbidity, with a 75% complete occlusion rate (6/8) at the last follow-up.

Clinical follow-up

The duration of clinical follow-up ranged from 24 to 54 months, with an average of 36.5 ± 9.7 months. Throughout this period, no delayed complications were identified. At the final clinical follow-up, a good clinical outcome was observed in 91.9% of patients. Of the 3 patients initially discharged with an mRS of 4 (n = 2) and mRS 2 (n = 1), two improved to an mRS of 1, while one remained at mRS 4. Patients with a poor clinical outcome had significantly larger aneurysm sizes compared to those with a good clinical outcome (p = .032). Furthermore, poor clinical outcomes at discharge were significantly associated with poor clinical outcomes at the last follow-up (p = .001) (Supplementary Table 3).

Discussion

The results of the current study demonstrated the applicability of the SBAC technique using low-profile braided stents, with a technical success rate of 97.2%. Braided stents contributed to progressive aneurysm occlusion, with higher rates of complete occlusion observed at follow-up. Safety and efficacy outcomes varied based on the location and size of the aneurysms. Outcomes were more favorable for small WNBAs, particularly those located at the MCA bifurcation.

In our study, immediate complete occlusion was achieved in 64.5% of the aneurysms. Even though it is a single stenting procedure, our immediate occlusion rates exceeded those of single stent-assisted coiling (SAC) series for WNBAs.^7–9 Our results were even comparable to or better than the DSAC series, with rates ranging from 25.4% to 59.1% reported.^10,11 Indeed, a drawback of DSAC is the potential immobilization of the coil catheter due to the trans-cell approach or fixation caused by fully deployed two stents. Bartolini et al. reported a 47.6% immediate occlusion rate in their series treated with X- or Y-configurated DSAC, primarily attributed to the immobilization of the coil catheter. ¹² In contrast, the SBAC technique allows catheterization of the aneurysm sac using a separate catheter, eliminating the need to navigate through the stents. This approach enables easier coil catheter repositioning for safer and more effective coiling. To our knowledge, there is only one reported SBAC series, where authors noted an 86.9% immediate occlusion rate for 61 aneurysms. However, it’s worth noting that 80.3% of the aneurysms in their study were small, with one-third being under 4 mm. ³

In the present study, we observed a complication rate of 32.4%, mainly due to thromboembolic complications. Aydin et al. reported a complications rate of 16%, with a 3.3% morbidity rate and no mortality. ³ We observed better safety and efficacy outcomes for small aneurysms. The larger average size of aneurysms and the higher incidence of AcomA cases (27%) may have contributed to our elevated complication rates. Our complication rates were either comparable to or higher than those in the DSAC series, which reported a range of 17% to 31.6%.^12–14 DSAC often requires catheterization through the struts of the initially placed stent, and deployment of the second stent from the struts of the first one. These maneuvers may lead to stent migration, thromboembolic, and hemorrhagic complications during the procedure.^12,15,16 Although SBAC technique offers a straightforward approach, we noted a high rate of complications. Possible reasons include the use of three microcatheters, which may elevate thromboembolic risk, and the requirement of DAPT, which is problematic if patients are non-compliant or have antiplatelet resistance. Additionally, our observed complication rate may appear disproportionately high due to our relatively small patient sample.

Single SAC series reported long-term complete occlusion rates ranging from of 31 to 70.3%.^7,9 The use of a single stent in the SBAC technique may raise concerns regarding the durability of this treatment. However, in our study, the long-term complete occlusion rate was 91.9%. These results are in line with a previously reported long-term complete occlusion rate of 89.1% and are also comparable to other techniques including clipping.^3,17,18 Adeep et al.'s SAC series for WNBAs introduced a scoring system to predict complete occlusion, observing a 100% rate for aneurysms under 4 mm. Our data shows a similar trend for smaller aneurysms, particularly in MCA bifurcation, underscoring size and location’s impact on complete occlusion rates. ⁷ Flow diverters have begun to be utilized for bifurcation aneurysms. Specifically, for MCA bifurcation aneurysms, complete occlusion rates have been reported at 78.7%, with a complication rate of 20.7%. ¹⁹ The WEB device remains an eligible and safe treatment option for WNBAs; however, a retreatment rate of 15.5% due to recanalization is clinically significant. ²⁰

The present study has several limitations. It is a non-randomized, retrospective, single-center investigation without a control group for alternative treatment. Furthermore, the limited sample size restricts the conclusiveness of our findings. The potential selection bias also cannot be dismissed. Prospective larger studies are needed to compare this technique’s safety and efficacy with other treatments, accounting for aneurysm characteristics.

Conclusion

The results of the present study show that the SBAC technique, when used with low-profile braided stents, is an effective and durable treatment for WNBAs. However, the overall complication rate is high. Subgroup analysis indicates promising safety and efficacy for MCA bifurcation aneurysms. For AcomA aneurysms, however, safety and efficacy profiles appear less favorable, suggesting that this technique could be a valuable option for select aneurysms.

Ethical statement

Ethical approval

This study obtained approval from the Ethics Committee for Clinical Research of Istanbul Fatih Sultan Mehmet Training and Research Hospital, University of Health Sciences, in the meeting held on 28.04.2022 with the study file number FSMEAH-KAEK 2022/37.

ORCID iDs

Ahmet Gunkan https://orcid.org/0000-0002-6236-5633

Esin Derin Cicek https://orcid.org/0000-0002-0391-3003