Endovascular detachable coil treatment has become the therapy of choice for most cerebral aneurysms since the introduction of the Guglielmi detachable coil in the 1990s.10,11 With the publication of the results of the International Subarachnoid Aneurysm Trial (ISAT) in 2002,17 endovascular coiling for ruptured brain aneurysms has become the mainstay of cerebral aneurysm treatment in Western Europe. The treatment has also been widely applied to unruptured cerebral aneurysms, resulting in an exponential increase in the pace of innovation in the field of interventional neuroradiology. Adjuncts that have been developed to assist the coiling include stents, balloon remodeling, and flow diverters.3,5,14,20
The Woven EndoBridge (WEB) device (Sequent Medical) provides a potential alternative to coiling as a treatment option for certain cerebral aneurysms, mainly wide-necked bifurcation aneurysms that present challenges for simple coiling. The WEB device is particularly suited to treating wide-necked aneurysms that are difficult to treat and have a high recurrence rate when treated with conventional coiling techniques. The device is a sphere of mixed-diameter nitinol wires braided to form a dense compliant mesh causing blood flow disruption and to create thrombosis and occlusion, thus preventing rupture. Currently, 3 generations of WEB device are in use (Fig. 1): the double layer (WEB DL), single layer (WEB SL), and single-layer sphere (WEB SLS). The WEB DL has a distal and a proximal layer of mesh and 3 radiopaque markers. The WEB SL and SLS each have only 1 layer of mesh and 2 radiopaque markers. The SLS differs from the SL in having a spherical shape and larger diameters. The proximal surface of the WEB device is concave to prevent thrombus. All WEB devices are sized by width and height. A handheld device uses electrothermal energy for deployment of the WEB device. All 3 types of the WEB device were included in this study and in our results.
A: A WEB DL device deployed from a catheter into a bifurcation aneurysm. B: A WEB SL device. C: A WEB SLS device. Copyright Sequent Medical. Published with permission. Figure is available in color online only.
Clinical use of the WEB device was first described in 2011.12 Because of the novelty of the device, its use has been reserved for selected patients who have limited alternative treatment options and expected technical difficulty with conventional coil embolization and/or clipping. The complications and clinical outcome with the WEB device must be studied to assess safety and clinical efficacy. In this study we used a national database to assess adverse events and clinical outcome in 109 consecutive patients to better understand the safety profile of this device.
Methods
Study Design
A national audit database was set up in September 2013 to audit safety information from all patients treated with a WEB device in the United Kingdom (UK; 14 centers). The database was password protected. Each center was able to enter its patient information. One hundred nine consecutive patients who underwent 112 procedures between March 2012 and March 2014 were entered into the database. The decision to use the WEB device was made based on various criteria at each center following a multidisciplinary meeting among clinicians. The criteria were related to aneurysm and aneurysm neck size, aneurysm location, and whether a neurosurgical option was available. Aneurysms suitable for standard coiling or clipping were excluded (unless patients refused the surgical option). Information was collected on clinical status according to the modified Rankin scale (mRS) both pre- and postprocedure. Procedural adverse events, technical events, and adjunctive device use were recorded. Data from up to March 2014 were collected retrospectively and from thereafter prospectively.
Technique
The general technique used to deliver the WEB device to the aneurysm has been described elsewhere.15,21 An 8-Fr guide sheath is placed in the main artery for navigation. A distal access catheter is often used for stability for delivering the device. Microcatheter selection is based on the size of the WEB device. The guidewire used was operator dependent, and subtle differences in the endovascular approach according to the operator were accepted but recorded in the database. All patients at all centers received an intraprocedural dose of intravenous heparin. Additional anticoagulation pre-, intra-, and postprocedure was given depending on the clinician and the case.
Adverse Event Analyses
Two independent interventional neuroradiologists (A.M. and R.S.) adjudicated the relationship of all reported adverse events and classified them into 5 categories: device related, procedure related, aneurysm disease related, ancillary device related, or related to another incidental condition. Data from the database were also categorized, and we found them to be in agreement with the adjudicated data.
Statistical Analyses
The statistical analysis was performed independently. The distributions of continuous variables were described using the means and standard deviations, and discrete variables were described as percentages. All statistical analyses were performed using the SPSS system, version 18.0.0 (SPSS Inc.).
Results
Baseline Characteristics of Patients and Aneurysms
One hundred nine patients underwent 112 consecutive procedures between March 2012 and March 2014 at 14 centers in the UK. The mean age of the patients was 56.5 years (SD 9.9 years). Each patient had 1 aneurysm determined to be suitable for WEB treatment (109 aneurysms). Two patients had 2 procedures given the failure of the first treatment, and 1 patient had a second WEB procedure because of a recurrence. Of the 109 patients, 103 (94.5%, 95% CI 88.4, 98.0) had a successful implant of the WEB device. Eight procedures were abandoned because of access issues; 2 patients went on to have a successful procedure. The procedure was elective in 91 patients (83.5%) and acute in 18 (16.5%). All aneurysms were saccular. Eight of the elective patients (7.3%) had partial thrombosis of the aneurysm. All 109 patients had a recorded preprocedure and discharge mRS score. One hundred patients had a follow-up mRS score from more than 3 months after the procedure.
Location of Aneurysms
Basilar aneurysms were the most common at 44 (40.4%) of 109, followed by middle cerebral artery (MCA) aneurysms at 39 (35.8%) of 109. The remaining aneurysms comprised those of the internal carotid artery (9 [8.2%] of 109), anterior communicating artery (8 [7.3%] of 109), posterior communicating artery (4 [3.7%] of 109), posterior cerebral artery (1 [1%] of 109), and anterior cerebral artery (4 [3.7%] of 109; Fig. 2). All patients had difficult to treat aneurysms that would not be suitable for unassisted coiling. Ninety-four aneurysms (86.2%) had a wide neck, 49 (45.0%) were bifurcation aneurysms, and 21 (19.3%) were not surgical candidates. Aneurysms were incidental in 64 patients (58.7%), 18 patients (16.5%) had acute subarachnoid hemorrhage (SAH), and 20 patients (18.3%) were symptomatic. Seven of the patients (6.4%) had recurrent aneurysms. The maximum aneurysm diameter ranged from 3.82 to 18.38 mm (mean 8.21 mm; Table 1). The maximum diameter of the aneurysm neck ranged from 2.35 to 11.42 mm (mean 6.18 mm).
Pie chart demonstrating the distribution of aneurysm locations. ACA = anterior cerebral artery; ACOM = anterior communicating artery; ICA = internal carotid artery; PCA = posterior cerebral artery; PCOM = posterior communicating artery. Figure is available in color online only.
Aneurysm characteristics
Parameter | Value |
---|---|
Max aneurysm diameter in mm | |
Mean (SD) | 8.21 (3.00) |
Max | 18.38 |
Min | 3.82 |
Max neck diameter in mm | |
Mean (SD) | 6.18 (1.77) |
Max | 11.42 |
Min | 2.35 |
Max aneurysm diameter (%)* | |
<7 mm | 33 (30.3) |
≥7 to <10 mm | 47 (43.1) |
≥10 mm | 29 (26.6) |
Max neck diameter (%)* | |
<4 mm | 1 (0.9) |
≥4 mm | 108 (99.1) |
Total of 109 aneurysms.
Treatment Analysis
One hundred three of the 109 patients (104 of 112 procedures) had successful deployment of the WEB device. One patient had 2 successful procedures on separate occasions. Fifty-seven procedures (54.8%) involved the WEB DL device; 11 of these procedures were acute and 46 were elective. Forty-one procedures (39.4%) involved the WEB SL device; 5 were acute and 36 were elective. Six procedures (5.8%) involved the WEB SLS device; 1 was acute and 5 were elective.
Safety Analysis
Inclusive of the abandoned procedures, 40 of the 109 patients had adverse events. Twenty-three of these events were unrelated to the WEB device. Recorded events included all minor events and technical events such as failed integrity test, alopecia, and disease or other events unrelated to the procedure or device. Eleven of these patients had persistent clinical symptoms related to an adverse event (Table 2), and 29 of the adverse events were without permanent clinical sequelae (Table 3). (Exclusive of abandoned procedures, 32 patients had recorded events. Nine of these patients had clinical symptoms [Table 2]. Twenty-three patients recovered with no new clinical symptoms [Table 3]). Presentation was classified as delayed if new symptoms developed after the first 3 months of follow-up and/or there was new radiographic evidence of an event at the > 3-month follow-up (with a previously normal followup scan with a modality of equal or greater sensitivity). The minimum follow-up for patients was more than 3 months, but 59 were followed up for more than 6 months and 14 of them were followed up for over a year (longest follow-up period 16 months).
Persistent clinical symptoms related to an adverse event in 11 patients who underwent WEB device placement
Case No. | Complications | Complication Category | WEB Device | Acute or Elective Procedure | Pretreatment mRS Score | Discharge mRS Score | mRS Score at >3-Mo FU | Adjuncts Used | Days From Procedure to Event | Related to WEB device? |
---|---|---|---|---|---|---|---|---|---|---|
1 | TE, vasospasm | Procedure | DL | Elective | 0 | 3 | 2 | No | 0 | No |
2 | TE | Procedure | SL | Elective | 0 | 2 | 2 | Yes | 0 | No |
3 | Rupture, TE | Device | DL | Elective | 0 | 0 | 1 | No | 0/21 | Yes |
4 | Thrombo event | Procedure | DL | Elective | 0 | 3 | 3 | No | 5 | No |
5 | Delayed rupture, death (300 days) | Disease | DL | Elective | 0 | 0 | 6 | Yes | 300 | No |
6 | Death (delayed rupture of different aneurysm) | Disease | DL | Elective | 0 | 0 | 6 | No | 336 | No |
7 | Other (hydrocephalus, SAH, death) | 1st: disease, 2nd: disease | 1st: DL, 2nd: SL | Elective | 1st: 1, 2nd: 3 | 1st: 0, 2nd: 3 | 1st: 3, 2nd: 6 | No | 259 | No |
8 | Parent vessel occlusion, TE, over-sized WEB | Device | DL | Elective | 0 | 1 | 1 | Yes | 0/0/0 | Yes |
9 | Other (delayed thrombo event, death) | AD (stent) | DL | Elective | 0 | 0 | 6 | No | 279 | No |
10 | Patient died due to comorbidities, access issue (abandoned) | Other | DL | Elective | 1 | 0 | 6 | Yes | 306 | No |
11 | Access issue, TE (abandoned) | Procedure | DL | Elective | 1 | 1 | 1 | No |
1st = first procedure; 2nd = second procedure; AD = ancillary device; FU = follow-up; TE = thromboembolism; thrombo = thromboembolic.
Adverse events without permanent clinical sequelae in 29 patients who underwent WEB device placement
Case No. | Complications | Complication Category | WEB Device | Acute or Elective Procedure | Pretreatment mRS Score | Discharge mRS Score | mRS Score at >3-Mo FU | Adjunct Used | Days From Procedure to Event | Event Related to WEB Device? |
---|---|---|---|---|---|---|---|---|---|---|
1 | Failed integrity test, other (transient neurological symptoms) | Device | DL | Elective | 0 | 0 | 0 | No | 0/233 | Yes/no |
2 | Nondetachment | Device | DL | Acute | 4 | 0 | 0 | No | 0 | Yes |
3 | Delivery wire caught | AD | DL | Elective | 1 | 0 | 0 | Yes | 0 | No |
4 | WEB wrong size, device protrusion | Device | DL | Elective | 0 | 0 | 0 | Yes | 0 | Yes |
5 | WEB wrong size, TE | Device | SL | Elective | 0 | 0 | 0 | Yes | 0/0 | Yes |
6 | WEB wrong size | Device | SL | Acute | 1 | 0 | 0 | No | 183 | Yes |
7 | TE, other (peripheral vascular event) | Device, procedure | DL | Acute | 5 | 0 | 0 | No | 0/0 | Yes/no |
8 | TE | Device | DL | Elective | 0 | 0 | 0 | No | 70/4 | Yes |
9 | TE | Device | DL | Elective | 0 | 0 | 0 | No | 0 | Yes |
10 | TE | Device | DL | Elective | 0 | 0 | 0 | No | 0 | Yes |
11 | TE | Procedure | SLS | Acute | 5 | 0 | 0 | No | 0 | No |
12 | TE | AD | SLS | Acute | 3 | 2 | 2 | No | 0 | No |
13 | TE | Procedure | SL | Elective | 2 | 2 | 1 | No | 0 | No |
14 | TE | Device | DL | Elective | 0 | 0 | 0 | No | 72 | Yes |
15 | TE | Device | SL | Elective | 0 | 0 | 0 | No | 24 | Yes |
16 | Parent vessel occlusion, rupture, WEB twisted & compressed | Device, AD | DL | Acute | 1 | 2 | 0 | No | 0/0/0 | Yes/no |
17 | Parent vessel occlusion | Device | DL | Elective | 0 | 0 | 0 | Yes | 0 | Yes |
18 | Rupture | AD | SLS | Elective | 0 | 0 | 0 | Yes | 0 | No |
19 | Other (transient headache) | Disease | DL | Elective | 0 | 0 | 0 | No | 7 | No |
20 | Other (aneurysm edema causing confusion-resolved) | Device | SL | Elective | 0 | 0 | 0 | No | 18 | Yes |
21 | Other (wound infection) | Other | SL | Acute | 5 | 0 | 0 | No | 16 | No |
22 | Procedural (alopecia), other (transient neurological symptoms) | Disease, procedure | SL | Elective | 0 | 0 | 0 | No | 87/87 | No/no |
23 | Other (SAH on LP, delayed rupture) | Device | SL | Elective | 0 | 0 | 0 | No | 218 | Yes |
24 | Access issue (abandoned) | Procedure | DL/SL/SLS | Elective | 0 | 0 | NR | Yes | 0 | No |
25 | Groin hematoma, access issue (abandoned) | Procedure | NR | Elective | 0 | 0 | NR | No | 1 | No |
26 | Access issue (abandoned) | Procedure | DL | Elective | 0 | 0 | 0 | No | 0 | No |
27 | Access issue (abandoned) | Procedure | DL | Elective | 0 | 0 | NR | Yes | 0 | No |
28 | Access issue (abandoned) | Procedure | NR | Elective | 0 | 0 | 0 | No | 0 | No |
29 | Access issue (abandoned) | Procedure | DL | Elective | 0 | 0 | NR | No | 0 | No |
LP = lumbar puncture; NR = not recorded.
Clinical Outcomes at Discharge and Follow-Up
All patients (109) had a discharge mRS score recorded. One hundred of the 109 patients had a > 3-month follow-up mRS score recorded; 9 patients had missing mRS scores at 3 or more months. Thus, long-term follow-up results are considered among 100 patients. The latest follow-up appointment and/or radiographic studies available were used for the assessment.
Preoperatively, 96 patients (88.1%, 95% CI 80.5, 93.5) had an mRS score < 3 (44.4% acute procedures, 96.7% elective) and 13 patients (11.9%, 95% CI 6.5, 19.5) had a score ≥ 3 (55.6% acute, 3.3% elective). Eighty patients (73.4%) had an mRS score of 0 (6.3% acute), 11 patients (10.1%) had an mRS score of 1 (9% acute), 5 patients (4.6%) had an mRS score of 2 (0% acute), 4 patients (3.7%) had an mRS score of 3 (50% acute), 4 patients (3.7%) had a score of 4 (75% acute), and 5 patients (4.6%) had a score of 5 (100% acute).
At discharge, 102 patients (93.6%, 95% CI 87.2, 97.4) had an mRS score < 3 (94.4% acute procedures, 93.4% elective) and 7 patients (6.4%, 95% CI 2.6, 12.8) had a score ≥ 3 (5.6% acute, 6.6% elective). Eighty-six patients (78.9%) had an mRS score of 0 (15.1% acute), 9 (8.2%) had a score of 1 (22.2% acute), 7 (6.4%) had a score of 2 (28.6% acute), 6 (5.5%) had a score of 3 (0% acute), 1 (0.9%) had a score of 4 (100% acute), and none had a score of 5 or 6.
At the > 3-month follow-up (100 patients), 91 patients (91%, 95% CI 83.6, 95.8) had an mRS score < 3 (100% acute procedures, 89.2% elective) and 9 patients (9%, 95% CI 4.2, 16.4) had an mRS score ≥ 3 (0% acute, 10.8% elective). Seventy-seven patients (77%) had an mRS score of 0 (19.5% acute), 8 (8%) had a score of 1 (1.3% acute), 6 (6%) had a score of 2 (16.7% acute), 4 (4%) had a score of 3 (0% acute), 0% had a score of 4 or 5, and 5 (5%) had a score of 6 (0% acute).
The evolution of the mRS score from before surgery to discharge showed that for 17.4% of patients (95% CI 10.8, 25.9) the mRS score improved (61.1% acute procedures, 8.8% elective), for 7.3% of patients (95% CI 3.2, 14.0) the mRS score deteriorated (5.6% acute, 7.7% elective), and for 75.2% of patients (95% CI 66.0, 83.0) the mRS score stayed the same (33.3% acute, 83.5% elective). At the follow-up (compared with preoperatively) the mRS score was better for 21.0% of patients (95% CI 13.5, 30.3; 76.5% acute, 9.6% elective), was worse for 12% (95% CI 6.4, 20.0; 0% acute, 14.5% elective), and stayed the same for 67.0% (95% CI 56.9, 76.1; 23.5% acute, 75.9% elective).
Overall morbidity at discharge was 1.8% (2 of 109 patients). One patient (Case 1; Table 2) had thromboembolism secondary to the procedure in addition to vasospasm from an acute SAH. A second patient (Case 4) developed right cerebellar infarcts and cerebellar ataxia 5 days after the procedure. Overall morbidity at the > 3-month followup was 6% (6 of 100). Morbidity was present if there was an increase in the mRS score to > 2. The patient in Case 4 did not improve at follow-up and thus was included in this later morbidity group. The other 5 patients were also included in the mortality group. The patient in Case 2 had a procedural thromboembolic event and developed hemianopia. The patient in Case 3, who underwent an elective procedure, had a procedural aneurysm rupture from a Synchro microwire. This patient also had a thromboembolic event, thought to be the result of a WEB device, causing right upper limb weakness and numbness. The patient in Case 8 had parent-vessel occlusion secondary to the inferior edge of the WEB device sitting across the proximal edge of A2. The clinician attempted to stent with the aim of preventing occlusion; however, it failed, and aggressive antiplatelet and hypertensive therapy were chosen. The patient in Case 11 had difficult intracranial access and had some mild left-hand weakness postprocedure (mRS Score 1). Other complications without clinical sequelae can be reviewed in Table 3.
Mortality and Other Complications
There were no in-hospital deaths. Five (5%) of 100 patients died after discharge and after the > 3-month follow-up. There were no device-related deaths as judged by 2 independent interventional neuroradiologists (A.M. and R.S.).
All later deaths occurred in patients with electively treated basilar aneurysms, constituting approximately 10% of the basilar aneurysms treated. All aneurysms in these cases were wide necked, but none were giant. One patient had a large, partially thrombosed aneurysm. The WEB device in all of these cases was the DL type, although 1 patient had retreatment with an SL device. One of the patients had a rebleed from a partially thrombosed basilar aneurysm (14 × 14 × 11 mm, 9-mm neck) previously treated with a WEB device. A second patient died of rupture of a second untreated, incidental small aneurysm 1 year after WEB treatment of the first aneurysm. Nine months after the first treatment of a basilar artery, a third patient represented with an aneurysm recurrence causing hydrocephalus. This patient was treated a second time with another WEB device and adjunctive coiling. This same patient then presented a third time with an SAH from the same aneurysm. Coiling was again performed, but the SAH was extensive, and there was pressure on the brainstem. A fourth patient died of brainstem ischemia from the basilar artery 10 days after retreatment with Y stenting and coiling for recurrence of a basilar tip aneurysm (previously treated electively with the WEB device). The fifth patient died of comorbidities (no association with the procedure or device).
When considering the overall complications, 14 were procedural, 17 were device related, 5 were related to the ancillary device, 6 were disease related, and 2 were categorized as “other.” Six patients had multiple categories. Within the symptomatic patient group, 4 complications were procedural, 3 were disease related, 2 were device related, 1 was related to the ancillary device, and 1 was classified as “other” (Tables 2 and 3).
The most common adverse event was thromboembolism, affecting 17 (15.6%) of 109 patients; 7 of these patients were symptomatic, and 10 had no clinical symptoms associated with the observed thromboembolic event. Seven cases were procedural, 9 were device related, 2 were ancillary device related, and none were disease related or “other” complications.
Anticoagulants were administered at the discretion of the clinician. As can be seen in Table 4, the anticoagulation regimen was variable throughout the population. Figure 3 shows that there is no obvious pattern between those who had clinical sequelae from the adverse event and those who did not. No centers employed pretreatment testing of antiplatelet therapy.
Anticoagulation for the thromboembolic events
Case No. | Clinical Sequelae | Elective or Acute Procedure | Anticoagulation Regimen | ||
---|---|---|---|---|---|
Preprocedural | Intraprocedural | Postprocedural | |||
1 | Yes | Elective | Aspirin 200 mg 5 days, clopidogrel 75 mg 5 days | Heparin 5000 U | Aspirin 75 mg 3 mos, clopidogrel 75 mg 1 mo |
2 | Yes | Elective | Clopidogrel 75 mg (already on) | Heparin 5000 U, aspirin 500 mg | Clopidogrel 75 mg indefinitely |
3 | Yes | Elective | Clopidogrel 600 mg 1 day, aspirin 300 mg 1 day | Heparin 5000 U | None (due to aneurysm rupture) |
4 | Yes | Elective | Aspirin 300 mg 1 day | Heparin 7000 U | None |
5 | Yes | Elective | None | Heparin 5000 U + 4800 U | None |
6 | Yes | Elective | Aspirin 75 mg (already taking) | Heparin 9000 U, aspirin 500 mg | Aspirin 75 mg indefinitely |
7 | Yes | Elective | Aspirin 75 mg 5 days, clopidogrel 300 mg 1 day | Heparin 5000 U | Aspirin 75 mg 3 days |
8 | No | Elective | Aspirin 75 mg 7 days, clopidogrel 75 mg 7 days | Heparin 6000 U | Aspirin 75 mg 1 yr, clopidogrel 75 mg 5 mos |
9 | No | Elective | None | Heparin 5000 U | Aspirin 75 mg 6 wks |
10 | No | Elective | None | Heparin 5000 U, aspirin 500 mg, ReoPro 10 mg | Heparin 20,000 U 1 day, aspirin 150 mg 12 mos, clopidogrel 75 mg 12 mos |
11 | No | Acute | Aspirin 300 mg 1 day | Heparin 7000 U, clopidogrel 600 mg, ReoPro 20 mg | None (acute) |
12 | No | Elective | Aspirin 300 mg, clopidogrel 600 mg | Heparin 6500 U | Aspirin 75 mg 12 mos, clopidogrel 75 mg 3 mos |
13 | No | Elective | None | Heparin 5000 U, aspirin 1000 mg | Aspirin 75 mg 3 mos |
14 | No | Acute | None | Aspirin 500 mg, heparin 5000 U | None (acute) |
15 | No | Acute | None | Heparin 5000 U, aspirin 500 mg | None (acute) |
16 | No (delayed TE) | Elective | None | Heparin 5000 U, aspirin 500 mg | None |
17 | No | Elective | Clopidogrel 600 mg for 1 day, aspirin 300 mg for 1 day | Heparin 1500 U | Aspirin 75 mg 4 mos |
Bar graph showing the percentage of patients receiving anticoagulation preprocedurally, intraprocedurally, and postprocedurally and who suffered thromboembolic complications. Figure is available in color online only.
Complications specific to the WEB device numbered 17 (15.6%) among the 109 patients; 2 patients were symptomatic. Twelve patients (70.6%) had WEB DL devices, 5 had SL devices (29.4%), and none had SLS devices (11.8%). The percentage of WEB DL devices within the device complication group (70.6%) is higher than the overall percentage of successfully deployed DL devices (54.8%). This suggests that the DL device may be associated with more complications; however, the sample is not large enough to draw reliable conclusions. Among the 17 device-related complications, 12 (70.6%) were immediate (0–7days), 2 (11.8%) occurred more than 7 days but less than 1 month after the procedure, 2 (11.8%) occurred more than 1 month but less than 6 months after the procedure, and 1 (5.9%) occurred more than 6 months but less than 1 year after the procedure. No morbidity (an increase in the mRS score to > 2) or mortality was associated with complications specific to the WEB device.
Learning Curve
On performing statistical analysis, we found no correlation to suggest that there was a learning curve with the device, but the numbers are insufficient to establish this. The analysis was performed using a split after the fifth case at each center, a split after the first half of patients from the full population, and a split after the first half of cases at each center. However, 14 centers were included in the study, and many different factors were taken into account. Because we used a registry, we did not have data regarding which clinician performed the procedure, so the analysis was done for each center rather than for an individual clinician (and some centers had multiple clinicians). The WEB device evolved during the study; the DL device was used initially, and the SL and SLS devices were used more in the later cases.
Abandoned Procedures
In our patient cohort, 8 procedures had to be abandoned. Two of the patients went on to have successful insertion of a WEB device at a later date. All 8 of the abandoned procedures were elective, and all patients in these cases had access issues. One patient had a groin hematoma, 1 had a thromboembolism, and 1 died during the follow-up period due to comorbidities. Following the attempted procedure, 2 patients had clinical sequelae and 6 did not. All abandoned procedures were included in the data analysis.
Discussion
The prevalence of cerebral aneurysms is considered to be approximately 3% in the general population.25 Approximately 8 patients per 100,000 of the population will experience rupture of a brain aneurysm.27 Since the ISAT, most cerebral aneurysms in Western Europe have been treated using endovascular techniques. However, this procedure can be very technically challenging, particularly in wide-necked bifurcation aneurysms.
Current endovascular techniques involve balloon-assisted coiling, stent-assisted coiling, flow diverters, and in some cases Y or T stenting. These techniques are complex, need considerable experience, require dual antiplatelet therapy to prevent thromboembolic complications, and have a high rate of adverse events.5,7 The benefit of stenting is diminished by the use of long-term antiplatelet medications. Many of the aneurysms in the current study, particularly those arising at the MCA bifurcation, would be surgical candidates for the above reasons.
The WEB device has been designed to facilitate interventional treatment in wide-necked aneurysms. The procedure is simple and fast and avoids a long-term antiplatelet regimen. The device is a novel solution for the treatment of wide-necked, complex bifurcation aneurysms. As with any new device, discovering its safety profile is paramount to assessing its utility. This series has been published to provide real-world outcomes that include every consecutive UK patient who received a WEB implant during introduction of the device into clinical use. While Sequent Medical funded the database, data entry and analysis were conducted by clinicians and research nurses independent of the company and were externally adjudicated. The study provides an unbiased snapshot of current practice, outcomes, and initial experience with the WEB device in clinical practice. Adverse events entered into the database were independently adjudicated and categorized by 2 senior interventional neuroradiologists. Most patients selected were not eligible for standard coiling and would have required adjunct devices. The surgical option was considered in the selected patients, but they either could not or did not want to have their aneurysm clipped.
The first publication on the WEB device described an animal study by Ding et al. in 2011.6 The authors found that the WEB device performed in a fashion similar to the platinum coil in 24 rabbits over the time frame of 1 year, suggesting that the WEB device could compete as a primary treatment device. A second animal study showed that 4 of 5 aneurysms were completely occluded immediately after placement of the WEB device. This study was followed by a series of 3 clinical case reports between 2011 and 2013 with a total of 6 patients having no recorded complications.4,12,26 Later, a case series of 6 ruptured aneurysms showed a procedural thromboembolic rate of 33.3%.2 Another series of 7 elective anterior communicating artery aneurysms had a procedural thromboembolic event rate of 14.3%.9
Table 5 presents 9 larger case studies with between 20 and 109 patients,1,15,16,19,21–24 showing all events reported in the studies including those without clinical sequelae. Given the importance of data on the safety profile of the device, current observational studies are key to ensuring evidence-based practices. This study from the UK is a timely addition to the growing body of European data. Table 5 demonstrates that the safety profile is similar across the studies. Procedure-related thromboembolism is the most common complication, having an impact on all of these larger studies (7.8%–18.8%) and raising the question of whether a standard anticoagulation policy should be employed for a limited time in patients receiving a WEB device. In the acute situation, however, preprocedural and postprocedural anticoagulation may not be an option.
Larger case series assessing complications of WEB device placement*
Parameter | Present Study | Leeds Data† | Pierot et al., 2016 | Papagiannaki et al., 2014 | Lubicz et al., 2014 | Lubicz et al., 2013 | Behme et al., 2015 | Pierot et al., 2015 | Pierot et al., 2013 | Pierot et al., 2012 |
---|---|---|---|---|---|---|---|---|---|---|
No. of patients | 109 | 22 | 113 | 77 | 45 | 18 | 51 | 62 | 32 | 20 |
Mortality | 5.0% | 0.0% | 0.0% | 0.0% | 2.2% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% |
Morbidity (mRS score >2 + increase of 1 point on mRS from preop) | 6.0% | 4.5% | 2.7% | 0.0% | 6.7% | 5.6% | 0.0% | 3.2% | 3.1% | 0.0% |
Procedural complication | ||||||||||
TE (clinical sequelae) | 15.6% (6.4%) | 13.6% (4.5%) | 15.0% (1.8%) | 11.7% (3.9%) | 11.1% (‡) | 11.1% (5.6%) | 7.8% (0%) | 16.1% (1.6%) | 18.8% (9.4%) | 10% (0%) |
Intraop rupture | 2.8% | 4.5% | 0.9% | 1.3% | 2.2% | 5.6% | 2.0% | 1.6% | 3.1% | 0% |
Studies with >15 patients, excluding abandoned procedures.
Pending publication.
Percentage could not be determined based on information in the study.
There has been a question of whether the thromboembolic events are secondary to the small marker at the base of the WEB implant or related to the access devices. A similar incidence of thromboembolic problems has been seen in treatments with flow diverters.8,18 The present study includes the early experience of operators and a greater number of WEB DL devices, which need larger access devices. We believe that this complication is probably related to large access devices rather than the WEB marker. The more recent trend is toward the SL and SLS devices, which are used with better access devices and smaller catheters as well as greater experience with the devices, which may reduce the risk of thromboembolic events.
The frequency of adverse events in our paper does not appear to differ between the acute or elective cases. The 9 cases with a worsening postprocedural mRS score were all in the elective group in patients with complex and difficult to treat aneurysms.
Ten percent of the basilar aneurysms treated in our series occurred in patients who subsequently died. None of these late deaths were attributed to the WEB device, and all happened more than 250 days from the date of the WEB procedure. One case was a delayed rupture at 300 days after the procedure. There was 1 delayed rupture of a different aneurysm 336 days after the procedure, and there was a death from the rupture of a partially thrombosed complex aneurysm after 259 days. A thromboembolic event occurred after a second procedure with a Y stent 279 days after the WEB procedure. A fifth patient died of comorbidities after 306 days.
Study Limitations and Strengths
A limitation of this study is that it is based on a registry. The WEB DL device was used in the early part of the study and is no longer routinely used in our clinical practice. Nine patients were lost to follow-up. There was also no consistent antiplatelet regimen used across the centers in the UK. The strength of the study is its consecutive series of patients from multiple centers, so it is probably representative of the introduction of the device into clinical practice. Moreover, the results have been reviewed and adjudicated by senior consultant interventional neuroradiologists.
The Raymond occlusion scale was used to record aneurysm occlusion success in this database (assessed within a subgroup of patients). This scale was developed to assess coiling and does not take into account the morphology of the WEB device. Thus, aneurysms with a proximal recess, proximal basket opacification, or slow flow within the WEB will not be correctly categorized. The recently developed Leeds WEB aneurysm occlusion scale has been carefully developed to include the nuances of the WEB device and will be invaluable for future monitoring of the device.13
This series has a wide selection of predominantly wide-necked aneurysms, a range of aneurysm locations, and a significant proportion of acute cases. The data suggest that the WEB device is a useful treatment option that makes more complex, wide-necked bifurcation aneurysms good candidates for endovascular treatment. The selection of predominantly basilar and MCA aneurysms in this UK series is different from that in other previous WEB publications. This is because most aneurysms included in this series were unsuitable for standard coiling and for surgery, which was judged to present a higher risk.
Incorrect sizing was recorded as an adverse event 4 times. We suggest using precise anteroposterior and lateral 3D measurements of the aneurysm to identify the appropriate implant size. Experience in simulation training is recommended before WEB implantation.
Conclusions
The UK results show that the WEB device has an acceptable safety profile for clinical use in selected aneurysms. A small risk of thromboembolic events should be minimized with appropriate anticoagulation in the perioperative period and correct sizing of the device. There is scope for further evaluation and optimization of an anticoagulation regimen for the WEB device.
Acknowledgments
We acknowledge support from Sequent Medical via Patricia Boyer and Phillippa Braidley.
Appendix
Participating Centers
1) Dr. Bhattacharya, Dr. Dervin, Irene Scott, Glasgow; 2) Dr. Patankar, Dr. Goddard, Miss Lawson, Jon Pearce, Leeds General Infirmary (lead center); 3) Dr. Lamin, Dr. Thomas, Joe Leyon, Birmingham; 4) Dr. Gholkar, Dr. White, Dr. Mitra, Dr. Krishnan, Nicola Hind, Newcastle; 5) Dr. Maliakal, Dr. Harrison, Hull Royal Infirmary; 6) Dr. Joshi, Cardiff; 7) Dr. Nair, Dr. Nagaraja, Coventry; 8) Dr. Adam Rennie, London; 9) Dr. Hewadkar, Dr. Williams, Dr. Stockley, Manchester; 10) Dr. Sonwalkar, Siddharta Wuppalapati, Steven Brown, Preston; 11) Dr. Alkilani, Romford; 12) Dr. Nahser, Dr. Putheran, Dr. Chandran, Liverpool; 13) Dr. Rennie, Belfast; and 14) Dr. Keston, Dr. Downer, Brian Innes, Edinburgh.
Disclosures
Dr. Gholkar is a consultant for Sequent Medical. Dr. Lamin has a consulting and training contract with Covidien, Sequent Medical, and Medtronic. Dr. Molyneux is a consultant for Sequent Medical. Dr. Patankar is a consultant for Sequent Medical, Stryker, and Pulsar Vascular and has received funding from Sequent Medical for statistical analysis in this study. Dr. Sellar is a consultant for Sequent Medical. Sequent Medical funded Axiom Fusion eClinical Suite to build the WEB UK study database and provided funding for the statistical analysis.
Author Contributions
Conception and design: Patankar. Acquisition of data: all authors. Analysis and interpretation of data: Patankar, Lawson. Drafting the article: Patankar, Lawson. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Patankar. Statistical analysis: Lawson. Administrative/technical/material support: Lawson. Study supervision: Patankar.
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