Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices
Original research
Long term follow-up of bifurcation aneurysms treated with braided stent assisted coiling and complex Tand Y- stent constructs Nicholas K Cheung,1 Albert HY Chiu,2,3,4 Andrew Cheung,2,4,3 Jason D Wenderoth2,4,3 1
Department of Medical Imaging, Royal Hobart Hospital, Tasmania, Australia 2 Department of Interventional Neuroradiology, Prince of Wales Hospital, New South Wales, Australia 3 Department of Interventional Neuroradiology, Prince of Wales Private Hospital, New South Wales, Australia 4 Department of Interventional Neuroradiology, Liverpool Hospital, New South Wales, Australia Correspondence to Dr Jason D Wenderoth, Suite 19, Level 7, Prince of Wales Private Hospital, Barker Street,Randwick, NSW 2031, Australia; dwenderoth@gmail. com Received 11 August 2017 Revised 5 September 2017 Accepted 8 September 2017
Abstract Background Stent assisted coil embolization (SACE) of bifurcation aneurysms is challenging. Heterogeneous results have been achieved to date, but largely for laser cut stents. While braided stents offer multiple technical advantages, their long term efficacy has yet to be validated. Objective To report the first long term 18 month results for the durability of bifurcation aneurysms treated with braided stents. Materials and methods Over a 4 year period, 59 consecutive patients with 60 bifurcation aneurysms underwent elective braided SACE across three Australian neurovascular centers. 17 of these aneurysms underwent T- or Y-shaped stent constructs. All patients had immediate, 6 month and 18 month clinical and radiological follow-up. Radiological assessment was made on modified Raymond–Roy occlusion scores while clinical assessment was based on the modified Rankin Scale. Subgroup analysis of 17 aneurysms treated with multi-stent constructs was conducted. Results 6 month follow-up data were available for 59 aneurysms and 18 month follow-up data for 58 aneurysms. Satisfactory aneurysm occlusion was achieved in 97% at inception and at 6 months, and 98% at 18 months. Good neurological outcomes were achieved in 95% at 18 months. Similar satisfactory results were achieved with the multi-stent construct cohort. Intraprocedural thromboembolic events were recorded in 5% and delayed events in 2%. Technical complications were found in 5%. All complication rate was 13%. Conclusion Braided SACE was safe, efficacious, and durable at the long term 18 month follow-up, including for multi-stent constructs. Preliminary results indicate favorable clinical and radiological outcomes compared with laser cut stents.
Introduction
To cite: Cheung NK, Chiu AHY, Cheung A, et al. J NeuroIntervent Surg Published Online First: [please include Day Month Year]. doi:10.1136/ neurintsurg-2017-013399
Wide necked bifurcation aneurysms represent a subset of aneurysms with specific treatment challenges due to the increased risk of coil prolapse.1 Stent assisted coil embolization (SACE) uses stents as a scaffold to prevent coil protrusion and is increasingly used for bifurcation aneurysms.2 3 However, SACE from the parent artery into one daughter branch predominantly protects the stented branch. A number of multi-stent configurations have since been proposed for protection of other branches, including the X-, T- and Y-shaped constructs.1 4–19 These results have been
promising, with low complication and occlusion rates.5 However, these studies reflect the use of laser cut stents only. Only three papers to date have reported follow-up results for braided stent constructs. However, only short term results are available, limiting understanding of the delayed complications and long term efficacy.6 20 21 This study is the first to report long term (minimum 18 months) clinical and radiological outcomes of elective treatment of bifurcation aneurysms with braided SACE, with a subgroup treated using complex T- or Y-stent constructs.
Methods Patient population
Between May 2012 and May 2015, 59 consecutive patients with 60 bifurcation aneurysms underwent braided SACE across three Australian neurovascular centers. All patients were treated for incidental (non-ruptured) saccular cerebral aneurysms. Prior to endovascular treatment, all patients were discussed in a neurovascular multidisciplinary team meeting where both open and endovascular approaches were considered and a consensus was reached; patients then gave informed consent after being presented with the treatment options, including no intervention, endovascular, or open surgical treatment. This study was approved by the Australian National Health and Medical Research Council.
Antithrombotic regimen
All braided SACE patients were premedicated with two antiplatelet medications. From May 2012 to February 2014 inclusive, all patients received a loading dose of 300 mg aspirin and 75 mg clopidogrel 7 days before the procedure, followed by 100 mg aspirin and 75 mg clopidogrel daily thereafter. From March 2014 onwards, clopidogrel was replaced with prasugrel, with 30 mg prasugrel loading 7 days before the procedure, followed by 5 mg prasugrel daily. Patients were continued on their dual antiplatelet regimen until 6 months post-procedure, where clopidogrel or prasugrel was stopped after evaluation with 3T MRI to ensure stent and parent vessel patency. Aspirin was continued indefinitely. Compliance with premedication was verified via telephone calls and a routine preadmission clinic appointment 2–5 days prior to the procedure.
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
1
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Intraprocedural systemic heparinization was given to reach a doubling of activated clotting time. This was followed by 24 hours of intravenous heparin infusion to maintain an activated partial thromboplastin time of 50–90 s.
Endovascular operation
All procedures were performed under general anesthesia. A 6–8 F guiding catheter was introduced through a femoral sheath into the carotid and/or vertebral artery. Evaluation and final measurements of the target vessel and aneurysm were obtained using both planar digital subtraction and three-dimensional rotational angiography. The choice of stents (Leo and Leo Baby (Balt Extrusion, Montmorency, France); Low Profile Visualized Intraluminal Support—LVIS and LVIS Jr (Microvention, Tustin, California, USA)) was based on operator preference. Tor Y-shaped stent constructs were used at the discretion of the senior operator. For T-shaped constructs, both daughter branches were catheterized. The short limb of the T-construct was deployed first. The choice of the short limb was based on which daughter branch had an origin closest to the orthogonal with the parent artery and parallel to the axis of the aneurysm neck. Deployment is achieved by pushing the proximal end of the stent out of the microcatheter in the final stages of deployment (rather than retrieving the catheter over the pusher wire), such that the last part of the stent is pushed free of the microcatheter around 2–4 mm proximal to the vessel bifurcation. The natural shortening tendency of the braided stent therefore results in shortening of the proximal end to lie parallel with and cover the aneurysm neck. After deployment of the short limb, the microcatheter is advanced over a wire into the aneurysm sac. The long limb of the T-construct is then deployed, and as the stent is deployed at the bifurcation, the microcatheter/stent system is given additional forward load to encourage a slight bulge of the mid-portion of the stent across the neck, such that it abuts the open proximal end of the short limb stent. Care is taken to ensure that there is sufficient length to achieve stable deployment of the proximal end of the long limb in the parent artery. Final deployment of the long limb of the T-construct results in jailing of the first microcatheter in the aneurysm sac. For Y-stent constructs, the coiling microcatheter is initially jailed by the deployment of the first stent, after which the second daughter branch artery is re-accessed through the cells of the first stent with the stent delivery microcatheter, followed by deployment of the second stent. Figure 1 and figure 2 show examples of the aneurysms treated in our series.
Data collection
Preoperatively, demographic data were collected from each patient while aneurysm data, including location, morphology, and size, stent devices used, and construct type were obtained perioperatively and placed in a de-identified registry. All intraoperative technical and any periprocedural and/or postoperative clinical complications were documented. Aneurysmal sac filling was reviewed by two authors (NKC and JDW) and quantified according to the modified Raymond–Roy occlusion scale.
Clinical follow-up
according to the modified Rankin Scale (mRS). Independent clinical follow-up was also undertaken at 3–12 months by the referring clinician.
Imaging follow-up
Cranial CT and CT angiography were performed routinely on day 1 post procedure to examine for any evidence of thromboembolic sequelae and stent patency. The first radiological follow-up imaging was performed using 3T MRI with time of flight angiography and/or gadolinium enhanced MR angiography (MRA) at 6 months. The 6 month cerebral DSA was performed in patients with contraindications to MRI. The second clinical follow-up was performed at 18 months with an accompanying DSA. In the rare occurrence where the patient was unable to undergo DSA, MRA was performed instead. Any patient with aneurysm recurrence or remnants were counseled accordingly.
Results
Patients were clinically reviewed by the treating interventional neuroradiologist immediately post procedure, at 2–4 hours, on day 1 post procedure, and at the 3 month clinic visit. Functional status was quantified at discharge, at the 3 month follow-up, and at the 18 month follow-up angiography visit, 2
Figure 1 T-stent deconstruction of the anterior communicating artery aneurysm. Top left: control DSA at inception. Top right: DSA immediately post-procedure (unsubtracted). Bottom left: post-procedural DSA (masked). Bottom right: 30 month DSA demonstrating complete occlusion of the aneurysm with no neck remnant. Normal flow through the stent construct, parent, and daughter arteries.
Fifty-nine patients with 60 elective unruptured aneurysms were included, of whom 59 underwent 6 month clinical and radiological follow-up. One was lost to the 6 month follow-up as the patient died of unrelated causes. Fifty-eight of the 60 aneurysms had an 18 month radiological follow-up. One patient refused to return, but was fit and asymptomatic. Fifty-one patients had
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices
Figure 2 T-stent deconstruction of a wide necked anterior communicating artery aneurysm. Top left: control three-dimensional DSA at inception. Top right: working projection during the procedure, demonstrating deployment of the T-stent construct, with the microcatheter jailed for deployment of coils. Bottom left: second working projection during the procedure. Bottom right: 18 month DSA demonstrating normal contrast opacification through the T-stent construct, parent, and daughter arteries. No aneurysm neck remnant or recurrence. an 18 month follow-up DSA, and seven patients had MRA. Table 1 demonstrates the patient cohort characteristics, aneurysm features, devices used, and bifurcation aneurysm location. All aneurysms except one were treated de novo. This patient had uncomplicated SACE treatment of a post-clipping aneurysmal remnant.
Procedural complications
Intraprocedural thromboembolic events occurred in three patients (5%), all in patients taking clopidogrel. Two cases involved intraoperative platelet aggregation, recognized and cleared with intraprocedural abciximab infusion. One patient developed transient hemiparesis, which recovered postoperatively with continued abciximab infusion over 12 hours. On discharge, he continued to have residual mild right upper limb weakness, which fully recovered to an 18 month mRS of 0. The second patient developed transient hypobulia and left hemiparesis post procedure, which recovered with intra-arterial abciximab. Her symptoms recovered fully prior to discharge, with no long term sequelae. The third patient developed a small left hemispheric embolic event post procedure, but no demonstrated stent thrombosis, resulting in right-handed weakness (mRS 2), which
responded very well to rehabilitation and occupational therapy interventions. Follow-up MRI results demonstrated a 5 mm ischemic focus within the deep white matter of the left frontal lobe. This was the only patient in our series that underwent SACE in two stages, initially with Y-stent construct placement, followed by coiling 4 months later. This was due to a technically difficult stent placement during the initial procedure, where one limb of a Y-construct did not fully open. One delayed stent thrombosis was encountered to date (2%), also on clopidogrel therapy. In this patient treated for an anterior communicating artery aneurysm, no complication was encountered on the 6 month MRA study. The 18 month DSA however demonstrated occlusion of the proximal limb of the stent situated within the A1 segment, with good distal A2 flow due to collateralization and the patient was asymptomatic (mRS 0). Since the substitution of prasugrel for clopidogrel in March 2014, no further cases of acute or delayed thromboembolic events were encountered in the 26 patients treated to date. Technical difficulties with stent positioning occurred in three patients (5%). One patient suffered an asymptomatic wire perforation and low volume subarachnoid hemorrhage during a T-stenting procedure, controlled with balloon inflation. There
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
3
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Table 1 Patient profiles. Demographic features of patients who underwent stent assisted coil embolization for treatment of cerebral aneurysm(s) and the stent type used for their treatment
Table 2 Summary of complications. Entire total encountered complications within this study, including those for the bifurcation subgroup cohort
Demographic variable
Complication
Total occurrence rate
Intraprocedural thromboembolic events
Without long term morbidity
2%(n=1/60)
With long term morbidity (mRS=2)
3% (n=2/60)
Number
Sex Male
19
Female
41
Age (years) Median
53
IQR
48–63
Stent type used
Without long term morbidity
2% (n=1/60)
Intraprocedural technical difficulties
Without long term morbidity
2% (n=1/60)
With long term morbidity (mRS=2 and 3)
3% (n=2/60)
Aneurysm recurrence
With mortality (mRS=6)
2% (n=1/59)
Technical complication rate
Without long term morbidity
5% (n=3/60)
With long term morbidity
7% (n=4/60)
Leo
5
Leo Baby
48
LVIS
6
Technical complication rate
LVIS Junior
1
All complications rate
Median
7
IQR
6–10
the only recurrence encountered in this series. No other aneurysms were retreated.
Aneurysm location (total cohort of 60) ICA terminus
6
Anterior communicating
29
MCA bifurcation
15
Basilar tip
10
Subanalysis of multi-stent constructs
Of the 17 aneurysms treated by T- and Y-stent constructs (15 with T-stents and 2 with Y-stents), 16 patients had 6 month follow-up. One died of unrelated causes prior to follow-up. A further 15 patients had 18 month DSA follow-up. The patient that declined follow-up was completely asymptomatic (mRS 0). Complications within this cohort included one asymptomatic wire perforation described above, and the single aneurysm recurrence with delayed hemorrhage resulting in death. Satisfactory occlusion at treatment was achieved in 88% of aneurysms, remaining at 88% at 6 months, and 94% at the 18 month follow-up. A detailed breakdown of these occlusion results is provided in table 3.
Complex T- or Y-stent construct aneurysm location (total cohort of 17) ICA terminus
0
Anterior communicating
7 (6 T-stents, 1 Y stent)
MCA bifurcation
7 (6 T-stents, 1 Y stent)
Basilar tip
3 (3 T-stents)
ICA, internal carotid artery; MCA, middle cerebral artery.
was no resultant neurological deficit post procedure or at the long term follow-up (mRS 0). In the second patient, a microcatheter aneurysm perforation occurred during deployment of a Leo Baby stent. This patient had an mRS score of 3 at the 18 month follow-up. The third patient is the same patient previously described who required a second stage coiling procedure, as one of the limbs of the Y-stent construct did not open completely. The breakdown of complications is summarized in table 2.
Aneurysmal occlusion
13% (n=8/60)
mRS, modified Rankin Scale.
Aneurysm size (max) (mm)
Aneurysms were deemed satisfactorily occluded if a Raymond– Roy occlusion score of 1 or 2 was achieved. Ninety-seven per cent of aneurysms were occluded at treatment. At the 6 month MRI follow-up, 97% were occluded. At the 18 month DSA follow-up, 98% were occluded. Further breakdown of the occlusion results for the bifurcation aneurysms is provided in table 3. One aneurysm recurred (2%) with coil compaction. This was the same patient who required a two stage procedure, due to technical difficulties with Y-stent deployment. The occlusion grade was 3b at the end of the first procedure, and 2 following the second coiling procedure. However, at the 18 month DSA follow-up, there was coil compaction evident, resulting in a Raymond-Roy score of 3a. This patient refused elective repacking and the aneurysm later ruptured resulting in death 2 years after the initial treatment. This was the only mortality and 4
Delayed stent thrombosis
Discussion
Wide necked sidewall and bifurcation aneurysms represent different technical entities, as side wall aneurysms requiring SACE are protected with a single stent whereas it can be challenging to protect both bifurcation branches with a single stent.13 This is because the stent provides definitive coil support for only one daughter branch, potentially allowing coils to prolapse into the other branch.22 The difficulty of treating bifurcation aneurysms is highlighted by previously published studies, with an 8% technical complication rate, intraoperative stent thrombosis in 20%, permanent morbidity in 4.3–17%, and occlusion rates of only 71% at the 6 month follow-up.22–24 Recurrence rates as high as 8% may occur as early as 1 month follow-up.22 A recent systematic review totaling 496 wide necked bifurcation aneurysms reported concordant results, including satisfactory neurological outcome of 86.3%, 72% occlusion rates, 5% retreatment rates, and permanent morbidity and mortality rates of 4.4% and 1%, respectively, but the majority included only 6 months of follow-up and hence not answering the persistent questions regarding long term treatment stability.2 This uncertainty has stimulated debate as to whether endovascular treatment or open surgical clipping is preferred. The endovascular community response has been the development of multiple stent constructs,23 particularly for treatment of wide necked anterior communicating artery bifurcation aneurysms.16 To date, however, there has been little published long term evidence for
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Table 3 Raymond–Roy occlusion scores for the total cohort, further segregated into bifurcation aneurysms and complex T- and Y-stent constructs subgroups Occlusion at 6 month follow-up (ROS=1, 2)
Occlusion at 18 month followup (ROS=1, 2) mRS score=0–1 at last follow-up mRS score=2–6 at last follow-up
Aneurysm
No treated
Occlusion at initial treatment (ROS=1, 2)
Bifurcation aneurysms
60
58/60 (97%)
57/59 (97%)
57/58 (98%)
ROS 1 ROS 2 ROS 3a ROS 3b
46/60 (77%) 12/60 (20%) 1/60 (2%) 1/60 (2%)
44/59 (75%) 13/59 (22%) 1/59 (2%) 1/59 (2%)
50/58 (86%) 7/58 (12%) 1/58 (6%) 0/58 (0%)
T- and Y-stents
17
15/17 (88%)
15/16 (94%)
15/16 (94%)
ROS 1 ROS 2 ROS 3a ROS 3b
7/17 (41%) 8/17 (47%) 1/17 (6%) 1/17 (6%)
6/16 (38%) 8/16 (50%) 2/16 (13%) 0/16 (0%)
11/16 (79%) 4/16 (29%) 1/16 (7%) 0/16 (0%)
56/59 (95%)
3/59 (5%)*
15/16 (94%)
1/16 (6%)
Satisfactory occlusion is determined by a Raymond–Roy occlusion score of 1 or 2. Modified Raymond–Roy occlusion score of 3a or 3b is deemed as a residual (or recurrent) aneurysm. *One patient with an mRS score of 3 had an mRS score of 3 at baseline, with an uncomplicated stent assisted coil embolization procedure. mRS, modified Rankin Scale; ROS, Raymond–Roy occlusion score.
the safety, efficacy, and durability of SACE for bifurcation aneurysms, including using multi-stent constructs. Many literature case series describe results for laser cut stents only,1 5–18 25 including those above. However, laser cut stents have limiting characteristics, including an inability to re-sheath and reposition when partially delivered, low radial force, and difficulties with visualization with only proximal and distal markers.26 Newer braided stents, such as the Leo and LVIS stents, addresses these problems. Their closed cell design includes a compliant cell size, enabling better wall apposition and scaffolding, while providing greater protection across the aneurysm neck and improved flow diversion.6 Thus they have a theoretical advantage over laser cut stents in that they can be ‘loaded’ into the bifurcation, focally increasing the stent diameter, cell density, and neck coverage in the region of the bifurcation, allowing greater coverage of both the aneurysm neck and the un-stented daughter branch. Furthermore, their variable cell size permits access with 0.017 inch microcatheters for coiling and/or insertion of a second stent in an X- or Y-configuration.19 In our experience, aneurysms located at bifurcations can usually be treated with a single braided stent, achieving good reconstruction of the bifurcation due to their superior conformity. In addition, braided stents possess radiopaque markers along their length, making them visible during deployment. For multiple stent constructs, braided stents also have advantages, since the compliance of cell size permits easier microcatheter passage through the stent, and reduced constraint of the second stent within the construct intersection. This allows better expansion and easier catheterization of the aneurysm.6 Despite the potential advantages, there are few braided SACE studies reporting treatment for bifurcation aneurysms and for aneurysms treated with multiple stent constructs. Some authors have even raised concerns with occlusion rates of braided stents, stating concerns with possible lack of full contact with aneurysm necks secondary to their homogeneous stretching closed cell design,27 and the potential unsuitability for use with bifurcation reconstructions28 Preliminary results indicate that short term results of braided stents are favorable, but long term results remain unknown. Some studies have reported the use of braided stents, but did not examine differences between laser cut and braided stents.29 Others used braided stents, but did not examine differences between side wall and bifurcation aneurysms.9 26 30 Outcomes
for aneurysms treated with multiple braided stent constructs are even more limited, with some employing this technique in only a very small proportion of patients,9 and braided stent results not separately reported from majority laser cut stent cohorts.1 Only four studies recorded aneurysms treated with braided SACE with subanalysis of bifurcation aneurysms. The first reported 6 month follow-up for 12 bifurcation aneurysms, with immediate occlusion in 92%, two technical complications, and one parent artery occlusion. However, nine patients received a second laser cut stent, rendering the efficacy of braided stents alone unknown.6 The second reported 22 aneurysms, achieving 73% occlusion at treatment and 91% at 6 months. One in-stent stenosis was encountered. However, the results were ambiguous as only 9/22 aneurysms were presumably bifurcation aneurysms, but the results were not reported separately.20 The third study recorded 34 aneurysms, with 50% immediate occlusion and 94% at follow-up, although some only had 1 month results. Of the 11 bifurcation aneurysms, the results were not segregated for this group.19 Lastly, a recent study reported 24 aneurysms treated with braided T-shaped stent constructs, recording 16.7% intraprocedural complications, delayed thromboembolic events in 4.2%, and permanent morbidity in 4.2%. Total occlusion rates of 81.2% at 3 month follow up, with a recurrence of 4.5% were reported. However, follow-up was as short as 3 months. Mid to long term results were unclear.21 To our knowledge, this study is the only series in the literature to date providing a minimum of 18 months of follow-up results for bifurcation aneurysms treated with braided SACE. We achieved overall 97% satisfactory occlusion rates at treatment, 97% at 6 months, and 98% at 18 months, with only 1 (2%) delayed recurrence. In our hands, treatment of bifurcation aneurysms with braided stents appeared to be safe, with 95% of patients scoring mRS of 0 or 1 at the 18 month follow-up. Only 2 (3%) patients had poor neurological outcomes (mRS >2) related to their procedure. Of these, there was 1 permanent neurological deficit and 1 delayed mortality. Although this study is not a direct comparison with laser cut SACE, our technical and clinical outcomes, in particular our occlusion rates, appear superior to those in a meta-analysis of 9.8% recanalization, retreatment in 5.2%, and long term occlusion rates of only 71.9% for laser cut treated bifurcation aneurysms. Reported permanent morbidity rates of 4.4% and a mortality rate of 1.0%
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
5
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices are similar.2 Within the multiple stent construct subgroup, our recorded occlusion rates of 88% at treatment, 94% at 6 months, and 94% at 18 months are comparable with a recent braided SACE study using T-shaped constructs, of 79% at treatment and 81.2% at the 3 month follow-up.21 Our overall all complication rate of 13% is also similar to the reported 16.7% total complication rate in the meta-analysis.2 The limitations of this study include the mixed retrospective and prospective nature of the cohort. Further longer term follow-up with a larger cohort of patients would validate our 18 month findings that braided SACE is a durable treatment for bifurcation aneurysms, including using T- and Y-stent constructs. Large scale randomized controlled trials comparing open repair with stent assisted coiling of these aneurysms would also be a valuable addition. Lastly, while our occlusion rates with braided stents appear superior compared with laser cut stents, we acknowledge that there are advantages laser cut stents offer over braided stents, including the predictability of deployed stent length. Braided stents, on the contrary, have the tendency to shorten after deployment from the catheter, and the length depends greatly on the diameter of the vessel that they are deployed into. For some authors, this may be a critical factor in determining the choice of stent used.
Conclusion
Our study, which represents the largest and most complete series to date with long term follow-up, suggests that braided SACE is safe, durable, and efficacious for the treatment of wide necked bifurcation aneurysms up to 18 months. It demonstrates the efficacy of this class of devices, including for use in multi-stent complex constructs for bifurcation aneurysms, especially when compared with the laser cut stent literature. This is likely due to the intrinsic properties of the stent, enhancing stent apposition, and contributions from flow diverting effects. Contributors All authors contributed to the planning and conducting of the research. Competing interests None declared. Patient consent Obtained. Ethics approval The study was approved by the National Health and Medical Research Council, Australian Research Council. Provenance and peer review Not commissioned; externally peer reviewed. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
References
1 Bartolini B, Blanc R, Pistocchi S, et al. "Y" and "X" stent-assisted coiling of complex and wide-neck intracranial bifurcation aneurysms. AJNR Am J Neuroradiol 2014;35:2153–8. 2 Zhao B, Yin R, Lanzino G, et al. Endovascular coiling of wide-neck and wide-neck bifurcation aneurysms: a systematic review and meta-analysis. AJNR Am J Neuroradiol 2016;37:1700–5. 3 McLaughlin N, McArthur DL, Martin NA. Use of stent-assisted coil embolization for the treatment of wide-necked aneurysms: a systematic review. Surg Neurol Int 2013;4:43. 4 Chow MM, Woo HH, Masaryk TJ, et al. A novel endovascular treatment of a widenecked basilar apex aneurysm by using a Y-configuration, double-stent technique. AJNR Am J Neuroradiol 2004;25:509–12. 5 Limbucci N, Renieri L, Nappini S, et al. Y-stent assisted coiling of bifurcation aneurysms with Enterprise stent: long-term follow-up. J Neurointerv Surg 2016;8:158–62.
6
6 Akmangit I, Aydin K, Sencer S, et al. Dual stenting using low-profile LEO baby stents for the endovascular management of challenging intracranial aneurysms. AJNR Am J Neuroradiol 2015;36:323–9. 7 Akgul E, Balli T, Aksungur EH. Hybrid, Y-configured, dual stent-assisted coil embolization in the treatment of wide-necked bifurcation aneurysms. Interv Neuroradiol 2015;21:29–39. 8 Ko JK, Han IH, Cho WH, et al. Crossing Y-stent technique with dual open-cell stents for coiling of wide-necked bifurcation aneurysms. Clin Neurol Neurosurg 2015;132:54–60. 9 Machi P, Costalat V, Lobotesis K, et al. LEO baby stent use following balloon-assisted coiling: single- and dual-stent technique-immediate and midterm results of 29 consecutive patients. AJNR Am J Neuroradiol 2015;36:2096–103. 10 Jeon P, Kim BM, Kim DJ, et al. Y-configuration double-stent-assisted coiling using two closed-cell stents for wide-neck basilar tip aneurysms. Acta Neurochir 2014;156:1677–86. 11 Cohen JE, Melamed I, Itshayek E. X-microstenting and transmesh coiling in the management of wide-necked tent-like anterior communicating artery aneurysms. J Clin Neurosci 2014;21:664–7. 12 Fargen KM, Mocco J, Neal D, et al. A multicenter study of stent-assisted coiling of cerebral aneurysms with a Y configuration. Neurosurgery 2013;73:466–72. 13 Yavuz K, Geyik S, Cekirge S, et al. Double stent-assisted coil embolization treatment for bifurcation aneurysms: immediate treatment results and long-term angiographic outcome. AJNR Am J Neuroradiol 2013;34:1778–84. 14 Spiotta AM, Gupta R, Fiorella D, et al. Mid-term results of endovascular coiling of wide-necked aneurysms using double stents in a Y configuration. Neurosurgery 2011;69:421–9. 15 Zhao KJ, Yang PF, Huang QH, et al. Y-configuration stent placement (crossing and kissing) for endovascular treatment of wide-neck cerebral aneurysms located at 4 different bifurcation sites. AJNR Am J Neuroradiol 2012;33:1310–6. 16 Cho YD, Park SW, Lee JY, et al. Nonoverlapping Y-configuration stenting technique with dual closed-cell stents in wide-neck basilar tip aneurysms. Neurosurgery 2012;70(2 Suppl Operative):ons244–ons249. 17 Menendez JY, Harrigan MR. X-configuration stent-assisted coiling. World Neurosurg 2010;74:143–4. 18 Lozen A, Manjila S, Rhiew R, et al. Y-stent-assisted coil embolization for the management of unruptured cerebral aneurysms: report of six cases. Acta Neurochir 2009;151:1663–72. 19 Behme D, Weber A, Kowoll A, et al. Low-profile visualized intraluminal support device (LVIS Jr) as a novel tool in the treatment of wide-necked intracranial aneurysms: initial experience in 32 cases. J Neurointerv Surg 2015;7:281–5. 20 Möhlenbruch M, Herweh C, Behrens L, et al. The LVIS Jr. microstent to assist coil embolization of wide-neck intracranial aneurysms: clinical study to assess safety and efficacy. Neuroradiology 2014;56:389–95. 21 Aydin K, Sencer S, Barburoglu M, et al. Midterm results of T-stent-assisted coiling of wide-necked and complex intracranial bifurcation aneurysms using low-profile stents. J Neurosurg 2017;0:1–9. 22 Huang Q, Xu Y, Hong B, et al. Stent-assisted embolization of wide-neck anterior communicating artery aneurysms: review of 21 consecutive cases. AJNR Am J Neuroradiol 2009;30:1502–6. 23 Yang P, Liu J, Huang Q, et al. Endovascular treatment of wide-neck middle cerebral artery aneurysms with stents: a review of 16 cases. AJNR Am J Neuroradiol 2010;31:940–6. 24 Vendrell JF, Costalat V, Brunel H, et al. Stent-assisted coiling of complex middle cerebral artery aneurysms: initial and midterm results. AJNR Am J Neuroradiol 2011;32:259–63. 25 Juszkat R, Nowak S, Smól S, et al. Leo stent for endovascular treatment of broadnecked and fusiform intracranial aneurysms. Interv Neuroradiol 2007;13:255–69. 26 Lv X, Li Y, Jiang C, et al. Potential advantages and limitations of the Leo stent in endovascular treatment of complex cerebral aneurysms. Eur J Radiol 2011;79:317–22. 27 Gross BA, Frerichs KU. Stent usage in the treatment of intracranial aneurysms: past, present and future. J Neurol Neurosurg Psychiatry 2013;84:244–53. 28 Krischek O, Miloslavski E, Fischer S, et al. A comparison of functional and physical properties of self-expanding intracranial stents [Neuroform3, Wingspan, Solitaire, Leo+, Enterprise]. Minim Invasive Neurosurg 2011;54:21–8. 29 Geyik S, Yavuz K, Yurttutan N, et al. Stent-assisted coiling in endovascular treatment of 500 consecutive cerebral aneurysms with long-term follow-up. AJNR Am J Neuroradiol 2013;34:2157–62. 30 Poncyljusz W, Biliński P, Safranow K, et al. The LVIS/LVIS Jr. stents in the treatment of wide-neck intracranial aneurysms: multicentre registry. J Neurointerv Surg 2015;7:524–9.
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
Long term follow-up of bifurcation aneurysms treated with braided stent assisted coiling and complex T- and Y- stent constructs Nicholas K Cheung, Albert HY Chiu, Andrew Cheung and Jason D Wenderoth J NeuroIntervent Surg published online September 29, 2017
Updated information and services can be found at: http://jnis.bmj.com/content/early/2017/09/28/neurintsurg-2017-01339 9
These include:
References Email alerting service
Topic Collections
This article cites 30 articles, 15 of which you can access for free at: http://jnis.bmj.com/content/early/2017/09/28/neurintsurg-2017-01339 9#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Articles on similar topics can be found in the following collections New devices (171)
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
New Devices
Original research
Long term follow-up of bifurcation aneurysms treated with braided stent assisted coiling and complex Tand Y- stent constructs Nicholas K Cheung,1 Albert HY Chiu,2,3,4 Andrew Cheung,2,4,3 Jason D Wenderoth2,4,3 1
Department of Medical Imaging, Royal Hobart Hospital, Tasmania, Australia 2 Department of Interventional Neuroradiology, Prince of Wales Hospital, New South Wales, Australia 3 Department of Interventional Neuroradiology, Prince of Wales Private Hospital, New South Wales, Australia 4 Department of Interventional Neuroradiology, Liverpool Hospital, New South Wales, Australia Correspondence to Dr Jason D Wenderoth, Suite 19, Level 7, Prince of Wales Private Hospital, Barker Street,Randwick, NSW 2031, Australia; dwenderoth@gmail. com Received 11 August 2017 Revised 5 September 2017 Accepted 8 September 2017
Abstract Background Stent assisted coil embolization (SACE) of bifurcation aneurysms is challenging. Heterogeneous results have been achieved to date, but largely for laser cut stents. While braided stents offer multiple technical advantages, their long term efficacy has yet to be validated. Objective To report the first long term 18 month results for the durability of bifurcation aneurysms treated with braided stents. Materials and methods Over a 4 year period, 59 consecutive patients with 60 bifurcation aneurysms underwent elective braided SACE across three Australian neurovascular centers. 17 of these aneurysms underwent T- or Y-shaped stent constructs. All patients had immediate, 6 month and 18 month clinical and radiological follow-up. Radiological assessment was made on modified Raymond–Roy occlusion scores while clinical assessment was based on the modified Rankin Scale. Subgroup analysis of 17 aneurysms treated with multi-stent constructs was conducted. Results 6 month follow-up data were available for 59 aneurysms and 18 month follow-up data for 58 aneurysms. Satisfactory aneurysm occlusion was achieved in 97% at inception and at 6 months, and 98% at 18 months. Good neurological outcomes were achieved in 95% at 18 months. Similar satisfactory results were achieved with the multi-stent construct cohort. Intraprocedural thromboembolic events were recorded in 5% and delayed events in 2%. Technical complications were found in 5%. All complication rate was 13%. Conclusion Braided SACE was safe, efficacious, and durable at the long term 18 month follow-up, including for multi-stent constructs. Preliminary results indicate favorable clinical and radiological outcomes compared with laser cut stents.
Introduction
To cite: Cheung NK, Chiu AHY, Cheung A, et al. J NeuroIntervent Surg Published Online First: [please include Day Month Year]. doi:10.1136/ neurintsurg-2017-013399
Wide necked bifurcation aneurysms represent a subset of aneurysms with specific treatment challenges due to the increased risk of coil prolapse.1 Stent assisted coil embolization (SACE) uses stents as a scaffold to prevent coil protrusion and is increasingly used for bifurcation aneurysms.2 3 However, SACE from the parent artery into one daughter branch predominantly protects the stented branch. A number of multi-stent configurations have since been proposed for protection of other branches, including the X-, T- and Y-shaped constructs.1 4–19 These results have been
promising, with low complication and occlusion rates.5 However, these studies reflect the use of laser cut stents only. Only three papers to date have reported follow-up results for braided stent constructs. However, only short term results are available, limiting understanding of the delayed complications and long term efficacy.6 20 21 This study is the first to report long term (minimum 18 months) clinical and radiological outcomes of elective treatment of bifurcation aneurysms with braided SACE, with a subgroup treated using complex T- or Y-stent constructs.
Methods Patient population
Between May 2012 and May 2015, 59 consecutive patients with 60 bifurcation aneurysms underwent braided SACE across three Australian neurovascular centers. All patients were treated for incidental (non-ruptured) saccular cerebral aneurysms. Prior to endovascular treatment, all patients were discussed in a neurovascular multidisciplinary team meeting where both open and endovascular approaches were considered and a consensus was reached; patients then gave informed consent after being presented with the treatment options, including no intervention, endovascular, or open surgical treatment. This study was approved by the Australian National Health and Medical Research Council.
Antithrombotic regimen
All braided SACE patients were premedicated with two antiplatelet medications. From May 2012 to February 2014 inclusive, all patients received a loading dose of 300 mg aspirin and 75 mg clopidogrel 7 days before the procedure, followed by 100 mg aspirin and 75 mg clopidogrel daily thereafter. From March 2014 onwards, clopidogrel was replaced with prasugrel, with 30 mg prasugrel loading 7 days before the procedure, followed by 5 mg prasugrel daily. Patients were continued on their dual antiplatelet regimen until 6 months post-procedure, where clopidogrel or prasugrel was stopped after evaluation with 3T MRI to ensure stent and parent vessel patency. Aspirin was continued indefinitely. Compliance with premedication was verified via telephone calls and a routine preadmission clinic appointment 2–5 days prior to the procedure.
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
1
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Intraprocedural systemic heparinization was given to reach a doubling of activated clotting time. This was followed by 24 hours of intravenous heparin infusion to maintain an activated partial thromboplastin time of 50–90 s.
Endovascular operation
All procedures were performed under general anesthesia. A 6–8 F guiding catheter was introduced through a femoral sheath into the carotid and/or vertebral artery. Evaluation and final measurements of the target vessel and aneurysm were obtained using both planar digital subtraction and three-dimensional rotational angiography. The choice of stents (Leo and Leo Baby (Balt Extrusion, Montmorency, France); Low Profile Visualized Intraluminal Support—LVIS and LVIS Jr (Microvention, Tustin, California, USA)) was based on operator preference. Tor Y-shaped stent constructs were used at the discretion of the senior operator. For T-shaped constructs, both daughter branches were catheterized. The short limb of the T-construct was deployed first. The choice of the short limb was based on which daughter branch had an origin closest to the orthogonal with the parent artery and parallel to the axis of the aneurysm neck. Deployment is achieved by pushing the proximal end of the stent out of the microcatheter in the final stages of deployment (rather than retrieving the catheter over the pusher wire), such that the last part of the stent is pushed free of the microcatheter around 2–4 mm proximal to the vessel bifurcation. The natural shortening tendency of the braided stent therefore results in shortening of the proximal end to lie parallel with and cover the aneurysm neck. After deployment of the short limb, the microcatheter is advanced over a wire into the aneurysm sac. The long limb of the T-construct is then deployed, and as the stent is deployed at the bifurcation, the microcatheter/stent system is given additional forward load to encourage a slight bulge of the mid-portion of the stent across the neck, such that it abuts the open proximal end of the short limb stent. Care is taken to ensure that there is sufficient length to achieve stable deployment of the proximal end of the long limb in the parent artery. Final deployment of the long limb of the T-construct results in jailing of the first microcatheter in the aneurysm sac. For Y-stent constructs, the coiling microcatheter is initially jailed by the deployment of the first stent, after which the second daughter branch artery is re-accessed through the cells of the first stent with the stent delivery microcatheter, followed by deployment of the second stent. Figure 1 and figure 2 show examples of the aneurysms treated in our series.
Data collection
Preoperatively, demographic data were collected from each patient while aneurysm data, including location, morphology, and size, stent devices used, and construct type were obtained perioperatively and placed in a de-identified registry. All intraoperative technical and any periprocedural and/or postoperative clinical complications were documented. Aneurysmal sac filling was reviewed by two authors (NKC and JDW) and quantified according to the modified Raymond–Roy occlusion scale.
Clinical follow-up
according to the modified Rankin Scale (mRS). Independent clinical follow-up was also undertaken at 3–12 months by the referring clinician.
Imaging follow-up
Cranial CT and CT angiography were performed routinely on day 1 post procedure to examine for any evidence of thromboembolic sequelae and stent patency. The first radiological follow-up imaging was performed using 3T MRI with time of flight angiography and/or gadolinium enhanced MR angiography (MRA) at 6 months. The 6 month cerebral DSA was performed in patients with contraindications to MRI. The second clinical follow-up was performed at 18 months with an accompanying DSA. In the rare occurrence where the patient was unable to undergo DSA, MRA was performed instead. Any patient with aneurysm recurrence or remnants were counseled accordingly.
Results
Patients were clinically reviewed by the treating interventional neuroradiologist immediately post procedure, at 2–4 hours, on day 1 post procedure, and at the 3 month clinic visit. Functional status was quantified at discharge, at the 3 month follow-up, and at the 18 month follow-up angiography visit, 2
Figure 1 T-stent deconstruction of the anterior communicating artery aneurysm. Top left: control DSA at inception. Top right: DSA immediately post-procedure (unsubtracted). Bottom left: post-procedural DSA (masked). Bottom right: 30 month DSA demonstrating complete occlusion of the aneurysm with no neck remnant. Normal flow through the stent construct, parent, and daughter arteries.
Fifty-nine patients with 60 elective unruptured aneurysms were included, of whom 59 underwent 6 month clinical and radiological follow-up. One was lost to the 6 month follow-up as the patient died of unrelated causes. Fifty-eight of the 60 aneurysms had an 18 month radiological follow-up. One patient refused to return, but was fit and asymptomatic. Fifty-one patients had
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices
Figure 2 T-stent deconstruction of a wide necked anterior communicating artery aneurysm. Top left: control three-dimensional DSA at inception. Top right: working projection during the procedure, demonstrating deployment of the T-stent construct, with the microcatheter jailed for deployment of coils. Bottom left: second working projection during the procedure. Bottom right: 18 month DSA demonstrating normal contrast opacification through the T-stent construct, parent, and daughter arteries. No aneurysm neck remnant or recurrence. an 18 month follow-up DSA, and seven patients had MRA. Table 1 demonstrates the patient cohort characteristics, aneurysm features, devices used, and bifurcation aneurysm location. All aneurysms except one were treated de novo. This patient had uncomplicated SACE treatment of a post-clipping aneurysmal remnant.
Procedural complications
Intraprocedural thromboembolic events occurred in three patients (5%), all in patients taking clopidogrel. Two cases involved intraoperative platelet aggregation, recognized and cleared with intraprocedural abciximab infusion. One patient developed transient hemiparesis, which recovered postoperatively with continued abciximab infusion over 12 hours. On discharge, he continued to have residual mild right upper limb weakness, which fully recovered to an 18 month mRS of 0. The second patient developed transient hypobulia and left hemiparesis post procedure, which recovered with intra-arterial abciximab. Her symptoms recovered fully prior to discharge, with no long term sequelae. The third patient developed a small left hemispheric embolic event post procedure, but no demonstrated stent thrombosis, resulting in right-handed weakness (mRS 2), which
responded very well to rehabilitation and occupational therapy interventions. Follow-up MRI results demonstrated a 5 mm ischemic focus within the deep white matter of the left frontal lobe. This was the only patient in our series that underwent SACE in two stages, initially with Y-stent construct placement, followed by coiling 4 months later. This was due to a technically difficult stent placement during the initial procedure, where one limb of a Y-construct did not fully open. One delayed stent thrombosis was encountered to date (2%), also on clopidogrel therapy. In this patient treated for an anterior communicating artery aneurysm, no complication was encountered on the 6 month MRA study. The 18 month DSA however demonstrated occlusion of the proximal limb of the stent situated within the A1 segment, with good distal A2 flow due to collateralization and the patient was asymptomatic (mRS 0). Since the substitution of prasugrel for clopidogrel in March 2014, no further cases of acute or delayed thromboembolic events were encountered in the 26 patients treated to date. Technical difficulties with stent positioning occurred in three patients (5%). One patient suffered an asymptomatic wire perforation and low volume subarachnoid hemorrhage during a T-stenting procedure, controlled with balloon inflation. There
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
3
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Table 1 Patient profiles. Demographic features of patients who underwent stent assisted coil embolization for treatment of cerebral aneurysm(s) and the stent type used for their treatment
Table 2 Summary of complications. Entire total encountered complications within this study, including those for the bifurcation subgroup cohort
Demographic variable
Complication
Total occurrence rate
Intraprocedural thromboembolic events
Without long term morbidity
2%(n=1/60)
With long term morbidity (mRS=2)
3% (n=2/60)
Number
Sex Male
19
Female
41
Age (years) Median
53
IQR
48–63
Stent type used
Without long term morbidity
2% (n=1/60)
Intraprocedural technical difficulties
Without long term morbidity
2% (n=1/60)
With long term morbidity (mRS=2 and 3)
3% (n=2/60)
Aneurysm recurrence
With mortality (mRS=6)
2% (n=1/59)
Technical complication rate
Without long term morbidity
5% (n=3/60)
With long term morbidity
7% (n=4/60)
Leo
5
Leo Baby
48
LVIS
6
Technical complication rate
LVIS Junior
1
All complications rate
Median
7
IQR
6–10
the only recurrence encountered in this series. No other aneurysms were retreated.
Aneurysm location (total cohort of 60) ICA terminus
6
Anterior communicating
29
MCA bifurcation
15
Basilar tip
10
Subanalysis of multi-stent constructs
Of the 17 aneurysms treated by T- and Y-stent constructs (15 with T-stents and 2 with Y-stents), 16 patients had 6 month follow-up. One died of unrelated causes prior to follow-up. A further 15 patients had 18 month DSA follow-up. The patient that declined follow-up was completely asymptomatic (mRS 0). Complications within this cohort included one asymptomatic wire perforation described above, and the single aneurysm recurrence with delayed hemorrhage resulting in death. Satisfactory occlusion at treatment was achieved in 88% of aneurysms, remaining at 88% at 6 months, and 94% at the 18 month follow-up. A detailed breakdown of these occlusion results is provided in table 3.
Complex T- or Y-stent construct aneurysm location (total cohort of 17) ICA terminus
0
Anterior communicating
7 (6 T-stents, 1 Y stent)
MCA bifurcation
7 (6 T-stents, 1 Y stent)
Basilar tip
3 (3 T-stents)
ICA, internal carotid artery; MCA, middle cerebral artery.
was no resultant neurological deficit post procedure or at the long term follow-up (mRS 0). In the second patient, a microcatheter aneurysm perforation occurred during deployment of a Leo Baby stent. This patient had an mRS score of 3 at the 18 month follow-up. The third patient is the same patient previously described who required a second stage coiling procedure, as one of the limbs of the Y-stent construct did not open completely. The breakdown of complications is summarized in table 2.
Aneurysmal occlusion
13% (n=8/60)
mRS, modified Rankin Scale.
Aneurysm size (max) (mm)
Aneurysms were deemed satisfactorily occluded if a Raymond– Roy occlusion score of 1 or 2 was achieved. Ninety-seven per cent of aneurysms were occluded at treatment. At the 6 month MRI follow-up, 97% were occluded. At the 18 month DSA follow-up, 98% were occluded. Further breakdown of the occlusion results for the bifurcation aneurysms is provided in table 3. One aneurysm recurred (2%) with coil compaction. This was the same patient who required a two stage procedure, due to technical difficulties with Y-stent deployment. The occlusion grade was 3b at the end of the first procedure, and 2 following the second coiling procedure. However, at the 18 month DSA follow-up, there was coil compaction evident, resulting in a Raymond-Roy score of 3a. This patient refused elective repacking and the aneurysm later ruptured resulting in death 2 years after the initial treatment. This was the only mortality and 4
Delayed stent thrombosis
Discussion
Wide necked sidewall and bifurcation aneurysms represent different technical entities, as side wall aneurysms requiring SACE are protected with a single stent whereas it can be challenging to protect both bifurcation branches with a single stent.13 This is because the stent provides definitive coil support for only one daughter branch, potentially allowing coils to prolapse into the other branch.22 The difficulty of treating bifurcation aneurysms is highlighted by previously published studies, with an 8% technical complication rate, intraoperative stent thrombosis in 20%, permanent morbidity in 4.3–17%, and occlusion rates of only 71% at the 6 month follow-up.22–24 Recurrence rates as high as 8% may occur as early as 1 month follow-up.22 A recent systematic review totaling 496 wide necked bifurcation aneurysms reported concordant results, including satisfactory neurological outcome of 86.3%, 72% occlusion rates, 5% retreatment rates, and permanent morbidity and mortality rates of 4.4% and 1%, respectively, but the majority included only 6 months of follow-up and hence not answering the persistent questions regarding long term treatment stability.2 This uncertainty has stimulated debate as to whether endovascular treatment or open surgical clipping is preferred. The endovascular community response has been the development of multiple stent constructs,23 particularly for treatment of wide necked anterior communicating artery bifurcation aneurysms.16 To date, however, there has been little published long term evidence for
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices Table 3 Raymond–Roy occlusion scores for the total cohort, further segregated into bifurcation aneurysms and complex T- and Y-stent constructs subgroups Occlusion at 6 month follow-up (ROS=1, 2)
Occlusion at 18 month followup (ROS=1, 2) mRS score=0–1 at last follow-up mRS score=2–6 at last follow-up
Aneurysm
No treated
Occlusion at initial treatment (ROS=1, 2)
Bifurcation aneurysms
60
58/60 (97%)
57/59 (97%)
57/58 (98%)
ROS 1 ROS 2 ROS 3a ROS 3b
46/60 (77%) 12/60 (20%) 1/60 (2%) 1/60 (2%)
44/59 (75%) 13/59 (22%) 1/59 (2%) 1/59 (2%)
50/58 (86%) 7/58 (12%) 1/58 (6%) 0/58 (0%)
T- and Y-stents
17
15/17 (88%)
15/16 (94%)
15/16 (94%)
ROS 1 ROS 2 ROS 3a ROS 3b
7/17 (41%) 8/17 (47%) 1/17 (6%) 1/17 (6%)
6/16 (38%) 8/16 (50%) 2/16 (13%) 0/16 (0%)
11/16 (79%) 4/16 (29%) 1/16 (7%) 0/16 (0%)
56/59 (95%)
3/59 (5%)*
15/16 (94%)
1/16 (6%)
Satisfactory occlusion is determined by a Raymond–Roy occlusion score of 1 or 2. Modified Raymond–Roy occlusion score of 3a or 3b is deemed as a residual (or recurrent) aneurysm. *One patient with an mRS score of 3 had an mRS score of 3 at baseline, with an uncomplicated stent assisted coil embolization procedure. mRS, modified Rankin Scale; ROS, Raymond–Roy occlusion score.
the safety, efficacy, and durability of SACE for bifurcation aneurysms, including using multi-stent constructs. Many literature case series describe results for laser cut stents only,1 5–18 25 including those above. However, laser cut stents have limiting characteristics, including an inability to re-sheath and reposition when partially delivered, low radial force, and difficulties with visualization with only proximal and distal markers.26 Newer braided stents, such as the Leo and LVIS stents, addresses these problems. Their closed cell design includes a compliant cell size, enabling better wall apposition and scaffolding, while providing greater protection across the aneurysm neck and improved flow diversion.6 Thus they have a theoretical advantage over laser cut stents in that they can be ‘loaded’ into the bifurcation, focally increasing the stent diameter, cell density, and neck coverage in the region of the bifurcation, allowing greater coverage of both the aneurysm neck and the un-stented daughter branch. Furthermore, their variable cell size permits access with 0.017 inch microcatheters for coiling and/or insertion of a second stent in an X- or Y-configuration.19 In our experience, aneurysms located at bifurcations can usually be treated with a single braided stent, achieving good reconstruction of the bifurcation due to their superior conformity. In addition, braided stents possess radiopaque markers along their length, making them visible during deployment. For multiple stent constructs, braided stents also have advantages, since the compliance of cell size permits easier microcatheter passage through the stent, and reduced constraint of the second stent within the construct intersection. This allows better expansion and easier catheterization of the aneurysm.6 Despite the potential advantages, there are few braided SACE studies reporting treatment for bifurcation aneurysms and for aneurysms treated with multiple stent constructs. Some authors have even raised concerns with occlusion rates of braided stents, stating concerns with possible lack of full contact with aneurysm necks secondary to their homogeneous stretching closed cell design,27 and the potential unsuitability for use with bifurcation reconstructions28 Preliminary results indicate that short term results of braided stents are favorable, but long term results remain unknown. Some studies have reported the use of braided stents, but did not examine differences between laser cut and braided stents.29 Others used braided stents, but did not examine differences between side wall and bifurcation aneurysms.9 26 30 Outcomes
for aneurysms treated with multiple braided stent constructs are even more limited, with some employing this technique in only a very small proportion of patients,9 and braided stent results not separately reported from majority laser cut stent cohorts.1 Only four studies recorded aneurysms treated with braided SACE with subanalysis of bifurcation aneurysms. The first reported 6 month follow-up for 12 bifurcation aneurysms, with immediate occlusion in 92%, two technical complications, and one parent artery occlusion. However, nine patients received a second laser cut stent, rendering the efficacy of braided stents alone unknown.6 The second reported 22 aneurysms, achieving 73% occlusion at treatment and 91% at 6 months. One in-stent stenosis was encountered. However, the results were ambiguous as only 9/22 aneurysms were presumably bifurcation aneurysms, but the results were not reported separately.20 The third study recorded 34 aneurysms, with 50% immediate occlusion and 94% at follow-up, although some only had 1 month results. Of the 11 bifurcation aneurysms, the results were not segregated for this group.19 Lastly, a recent study reported 24 aneurysms treated with braided T-shaped stent constructs, recording 16.7% intraprocedural complications, delayed thromboembolic events in 4.2%, and permanent morbidity in 4.2%. Total occlusion rates of 81.2% at 3 month follow up, with a recurrence of 4.5% were reported. However, follow-up was as short as 3 months. Mid to long term results were unclear.21 To our knowledge, this study is the only series in the literature to date providing a minimum of 18 months of follow-up results for bifurcation aneurysms treated with braided SACE. We achieved overall 97% satisfactory occlusion rates at treatment, 97% at 6 months, and 98% at 18 months, with only 1 (2%) delayed recurrence. In our hands, treatment of bifurcation aneurysms with braided stents appeared to be safe, with 95% of patients scoring mRS of 0 or 1 at the 18 month follow-up. Only 2 (3%) patients had poor neurological outcomes (mRS >2) related to their procedure. Of these, there was 1 permanent neurological deficit and 1 delayed mortality. Although this study is not a direct comparison with laser cut SACE, our technical and clinical outcomes, in particular our occlusion rates, appear superior to those in a meta-analysis of 9.8% recanalization, retreatment in 5.2%, and long term occlusion rates of only 71.9% for laser cut treated bifurcation aneurysms. Reported permanent morbidity rates of 4.4% and a mortality rate of 1.0%
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
5
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
New Devices are similar.2 Within the multiple stent construct subgroup, our recorded occlusion rates of 88% at treatment, 94% at 6 months, and 94% at 18 months are comparable with a recent braided SACE study using T-shaped constructs, of 79% at treatment and 81.2% at the 3 month follow-up.21 Our overall all complication rate of 13% is also similar to the reported 16.7% total complication rate in the meta-analysis.2 The limitations of this study include the mixed retrospective and prospective nature of the cohort. Further longer term follow-up with a larger cohort of patients would validate our 18 month findings that braided SACE is a durable treatment for bifurcation aneurysms, including using T- and Y-stent constructs. Large scale randomized controlled trials comparing open repair with stent assisted coiling of these aneurysms would also be a valuable addition. Lastly, while our occlusion rates with braided stents appear superior compared with laser cut stents, we acknowledge that there are advantages laser cut stents offer over braided stents, including the predictability of deployed stent length. Braided stents, on the contrary, have the tendency to shorten after deployment from the catheter, and the length depends greatly on the diameter of the vessel that they are deployed into. For some authors, this may be a critical factor in determining the choice of stent used.
Conclusion
Our study, which represents the largest and most complete series to date with long term follow-up, suggests that braided SACE is safe, durable, and efficacious for the treatment of wide necked bifurcation aneurysms up to 18 months. It demonstrates the efficacy of this class of devices, including for use in multi-stent complex constructs for bifurcation aneurysms, especially when compared with the laser cut stent literature. This is likely due to the intrinsic properties of the stent, enhancing stent apposition, and contributions from flow diverting effects. Contributors All authors contributed to the planning and conducting of the research. Competing interests None declared. Patient consent Obtained. Ethics approval The study was approved by the National Health and Medical Research Council, Australian Research Council. Provenance and peer review Not commissioned; externally peer reviewed. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
References
1 Bartolini B, Blanc R, Pistocchi S, et al. "Y" and "X" stent-assisted coiling of complex and wide-neck intracranial bifurcation aneurysms. AJNR Am J Neuroradiol 2014;35:2153–8. 2 Zhao B, Yin R, Lanzino G, et al. Endovascular coiling of wide-neck and wide-neck bifurcation aneurysms: a systematic review and meta-analysis. AJNR Am J Neuroradiol 2016;37:1700–5. 3 McLaughlin N, McArthur DL, Martin NA. Use of stent-assisted coil embolization for the treatment of wide-necked aneurysms: a systematic review. Surg Neurol Int 2013;4:43. 4 Chow MM, Woo HH, Masaryk TJ, et al. A novel endovascular treatment of a widenecked basilar apex aneurysm by using a Y-configuration, double-stent technique. AJNR Am J Neuroradiol 2004;25:509–12. 5 Limbucci N, Renieri L, Nappini S, et al. Y-stent assisted coiling of bifurcation aneurysms with Enterprise stent: long-term follow-up. J Neurointerv Surg 2016;8:158–62.
6
6 Akmangit I, Aydin K, Sencer S, et al. Dual stenting using low-profile LEO baby stents for the endovascular management of challenging intracranial aneurysms. AJNR Am J Neuroradiol 2015;36:323–9. 7 Akgul E, Balli T, Aksungur EH. Hybrid, Y-configured, dual stent-assisted coil embolization in the treatment of wide-necked bifurcation aneurysms. Interv Neuroradiol 2015;21:29–39. 8 Ko JK, Han IH, Cho WH, et al. Crossing Y-stent technique with dual open-cell stents for coiling of wide-necked bifurcation aneurysms. Clin Neurol Neurosurg 2015;132:54–60. 9 Machi P, Costalat V, Lobotesis K, et al. LEO baby stent use following balloon-assisted coiling: single- and dual-stent technique-immediate and midterm results of 29 consecutive patients. AJNR Am J Neuroradiol 2015;36:2096–103. 10 Jeon P, Kim BM, Kim DJ, et al. Y-configuration double-stent-assisted coiling using two closed-cell stents for wide-neck basilar tip aneurysms. Acta Neurochir 2014;156:1677–86. 11 Cohen JE, Melamed I, Itshayek E. X-microstenting and transmesh coiling in the management of wide-necked tent-like anterior communicating artery aneurysms. J Clin Neurosci 2014;21:664–7. 12 Fargen KM, Mocco J, Neal D, et al. A multicenter study of stent-assisted coiling of cerebral aneurysms with a Y configuration. Neurosurgery 2013;73:466–72. 13 Yavuz K, Geyik S, Cekirge S, et al. Double stent-assisted coil embolization treatment for bifurcation aneurysms: immediate treatment results and long-term angiographic outcome. AJNR Am J Neuroradiol 2013;34:1778–84. 14 Spiotta AM, Gupta R, Fiorella D, et al. Mid-term results of endovascular coiling of wide-necked aneurysms using double stents in a Y configuration. Neurosurgery 2011;69:421–9. 15 Zhao KJ, Yang PF, Huang QH, et al. Y-configuration stent placement (crossing and kissing) for endovascular treatment of wide-neck cerebral aneurysms located at 4 different bifurcation sites. AJNR Am J Neuroradiol 2012;33:1310–6. 16 Cho YD, Park SW, Lee JY, et al. Nonoverlapping Y-configuration stenting technique with dual closed-cell stents in wide-neck basilar tip aneurysms. Neurosurgery 2012;70(2 Suppl Operative):ons244–ons249. 17 Menendez JY, Harrigan MR. X-configuration stent-assisted coiling. World Neurosurg 2010;74:143–4. 18 Lozen A, Manjila S, Rhiew R, et al. Y-stent-assisted coil embolization for the management of unruptured cerebral aneurysms: report of six cases. Acta Neurochir 2009;151:1663–72. 19 Behme D, Weber A, Kowoll A, et al. Low-profile visualized intraluminal support device (LVIS Jr) as a novel tool in the treatment of wide-necked intracranial aneurysms: initial experience in 32 cases. J Neurointerv Surg 2015;7:281–5. 20 Möhlenbruch M, Herweh C, Behrens L, et al. The LVIS Jr. microstent to assist coil embolization of wide-neck intracranial aneurysms: clinical study to assess safety and efficacy. Neuroradiology 2014;56:389–95. 21 Aydin K, Sencer S, Barburoglu M, et al. Midterm results of T-stent-assisted coiling of wide-necked and complex intracranial bifurcation aneurysms using low-profile stents. J Neurosurg 2017;0:1–9. 22 Huang Q, Xu Y, Hong B, et al. Stent-assisted embolization of wide-neck anterior communicating artery aneurysms: review of 21 consecutive cases. AJNR Am J Neuroradiol 2009;30:1502–6. 23 Yang P, Liu J, Huang Q, et al. Endovascular treatment of wide-neck middle cerebral artery aneurysms with stents: a review of 16 cases. AJNR Am J Neuroradiol 2010;31:940–6. 24 Vendrell JF, Costalat V, Brunel H, et al. Stent-assisted coiling of complex middle cerebral artery aneurysms: initial and midterm results. AJNR Am J Neuroradiol 2011;32:259–63. 25 Juszkat R, Nowak S, Smól S, et al. Leo stent for endovascular treatment of broadnecked and fusiform intracranial aneurysms. Interv Neuroradiol 2007;13:255–69. 26 Lv X, Li Y, Jiang C, et al. Potential advantages and limitations of the Leo stent in endovascular treatment of complex cerebral aneurysms. Eur J Radiol 2011;79:317–22. 27 Gross BA, Frerichs KU. Stent usage in the treatment of intracranial aneurysms: past, present and future. J Neurol Neurosurg Psychiatry 2013;84:244–53. 28 Krischek O, Miloslavski E, Fischer S, et al. A comparison of functional and physical properties of self-expanding intracranial stents [Neuroform3, Wingspan, Solitaire, Leo+, Enterprise]. Minim Invasive Neurosurg 2011;54:21–8. 29 Geyik S, Yavuz K, Yurttutan N, et al. Stent-assisted coiling in endovascular treatment of 500 consecutive cerebral aneurysms with long-term follow-up. AJNR Am J Neuroradiol 2013;34:2157–62. 30 Poncyljusz W, Biliński P, Safranow K, et al. The LVIS/LVIS Jr. stents in the treatment of wide-neck intracranial aneurysms: multicentre registry. J Neurointerv Surg 2015;7:524–9.
Cheung NK, et al. J NeuroIntervent Surg 2017;0:1–6. doi:10.1136/neurintsurg-2017-013399
Downloaded from http://jnis.bmj.com/ on September 29, 2017 - Published by group.bmj.com
Long term follow-up of bifurcation aneurysms treated with braided stent assisted coiling and complex T- and Y- stent constructs Nicholas K Cheung, Albert HY Chiu, Andrew Cheung and Jason D Wenderoth J NeuroIntervent Surg published online September 29, 2017
Updated information and services can be found at: http://jnis.bmj.com/content/early/2017/09/28/neurintsurg-2017-01339 9
These include:
References Email alerting service
Topic Collections
This article cites 30 articles, 15 of which you can access for free at: http://jnis.bmj.com/content/early/2017/09/28/neurintsurg-2017-01339 9#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Articles on similar topics can be found in the following collections New devices (171)
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
