A Meta-Analysis of Mid-Term Outcomes of Endovascular Aneurysm Sealing

Abstract

Background-Aim:

Several studies have been published showing conflicting results on the outcome after endovascular aneurysm sealing (EVAS). The aim of the present study is to conduct a systematic review and meta-analysis of published evidence to assess the efficacy of EVAS in the management of patients with abdominal aortic aneurysm (AAA).

Methods:

An electronic search of the English medical literature, from 2010 to March 2021, was conducted using MEDLINE, EMBASE, and Cochrane databases to find studies relevant to outcome after EVAS.

Results:

The final analysis included 12 articles published between 2011 and 2021, including 1440 patients. In total, 79.3% of the included patients underwent aneurysm treatment according to the instructions for use. Technical success was 98.8%. Overall, 30-day mortality was 1.3%. Procedure-related complications were reported in 4% of the cohort. During median follow-up of 28.1 months (range 9–72 months), the pooled estimate of endoleak type I, migration and reinterventions was 16% (95% confidence interval [CI]=7–25), 16% (95% CI=9–23), and 19% (95% CI=11–28), respectively. In a sub-analysis, 7 studies (703 patients) reported outcome with a mean follow-up of more than 2 years (range 24–72 months). In these studies, the pooled estimate of endoleak type I, migration, and reinterventions was 25% (95% CI=13–38), 22% (95% CI=19–26), and 27% (95% CI=21–33), respectively.

Conclusion:

Patients who have been treated with EVAS are in high risk for reintervention especially beyond 2 years following implantation. Close surveillance for patients treated with EVAS is mandatory.

Keywords

EVAS Nellix endovascular aneurysm sealing abdominal aortic aneurysm aneurysm sac endovascular aneurysm repair

Introduction

Endovascular aneurysm repair (EVAR) has gained wide acceptance as the primary treatment choice in patients with abdominal aortic aneurysm (AAA) and favorable anatomy.¹ Even though randomized controlled trials showed a marked benefit in 30-day outcomes, such benefit declines or even become lost over the mid-term follow-up.² Aneurysm-related adverse events such as endoleak and migration still occur consisting major contributors of reinterventions. Especially, type II endoleak (EII) seems a common finding after EVAR and despite its usual benign course may sometimes lead to a worse outcome.³ New devices are continuously being developed to eliminate or even prevent EVAR-related complications and enforce EVAR durability.

In 2011, a novel concept of endovascular AAA treatment was introduced in clinical practice.⁴ Endovascular aneurysm sealing (EVAS) technique is characterized by obliteration of the aneurysmal sac by polymer-ﬁlled endobags, while maintaining the normal flow to lower extremities with two balloon expandable stent grafts. This design was specifically developed to overcome EII, by sealing the device at the top and bottom proximally and distally and additionally, providing positional stability of the endograft and preventing retrograde side branch flow, by filling the aneurysm sac. The single-piece conformation of the stents eliminates the threat of component separation and type III endoleaks. Other benefits of the system include reduced procedure times and radiation dose, compared with standard endografts, while there is also no need for contralateral limb catheterization.^3–5 The device was also supposed to be able to treat anatomies not suited for standard EVAR.⁶ The early results of EVAS were encouraging with a high aneurysm exclusion and low endoleak and migration rates, even when used outside of the initial 2013 instructions for use (IFUs).^4–7 Despite this, in response to observations of device failure made in some registries, the endograft’s IFUs were refined in 2016 (Table 1). The revised IFUs narrowed considerably the range of morphological characteristics that render an aneurysm suitable for on-label EVAS.⁸

Table 1.

Modifications of the IFU of the Nellix Device Between the Original IFU-2013 and the Revised IFU-2016.

IFU 2013	IFU 2016
Proximal neck diameter 18–32mm	Proximal neck diameter 18–28mm
Infrarenal neck length ≥10mm	Criteria remain the same; definition of proximal neck length is changed to diameter change of 10% vs previous 20%
Infrarenal neck angle ≤60°	No change
Aneurysm blood lumen diameter ≤70mm	No change
Not applicable	Ratio of maximum aortic aneurysm diameter to maximum aortic blood lumen diameter <1.4
Iliac artery luminal diameter 9–35mm	Iliac artery lumen diameter 9–35mm outside the distal seal zone Distal iliac artery seal zone length ≥10mm with maximum 25mm diameter (inner to inner)
Femoral access ≥ 7mm	No change

Abbreviation: IFU, instructions for use.

In recent years several studies have been published showing conflicting results on EVAS outcomes. Recently, device manufacturer (Endologix Inc., Irvine, CA, USA) voluntarily recalled the device and sent security issues to all users. The aim of this study was to conduct a systematic review and meta-analysis of the literature assessing the efficacy of EVAS in AAA treatment.

Methods

Eligibility criteria: The objectives, methodology of the systematic review and analysis, and the inclusion criteria for study enrollment were prespecified. Standard Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed and documented in advance in a formal protocol.⁹ Ethics approval was not required. Data extraction and methodological assessment were performed by 2 independent investigators (G.K., P.N.). Types of outcome measures included type I endoleak, stent-graft migration, aneurysm-related reinterventions, thrombosis, and mortality. Standardized and accepted definitions of device failure were used. Technical success was defined as successful deployment without any sign of a type I or III endoleak, limb occlusion, or stent fracture at completion angiography. Reintervention was defined as any procedure required to maintain aneurysm exclusion. Stent-graft migration was defined as migration of the most proximal end at least 5mm in a caudal direction. Aneurysm-related death was defined as any death related to the aneurysm itself. Studies considered for inclusion and full-text review fulfilled the following criteria: (1) to report on EVAS, (2) to include at least 5 patients treated, and (3) to provide data on 30-day and follow-up outcomes including migration, endoleak, thrombosis, and death. The exclusion criteria included (1) case reports or case series reporting on less than 10 patients; (2) reviews, letters to the editor, and editorials; (3) studies with potential overlap (the latest published study or the study with the higher number of patients was considered for eligibility), (4) studies reporting only on anatomic evaluations and eligibility; (5) studies reporting on outcomes other than the aforementioned (endoleak, migration, thrombosis, and death); (6) studies including patients with abdominal pathologies other than infrarenal AAA or reporting on urgent and/or emergent cases. The same reviewers (G.K., P.N.) evaluated the eligibility of studies for inclusion in this review independently in a nonblinded standardized manner. Disagreements were resolved by discussion with the senior author (E.V.).

Search: An electronic search of the English medical literature from 2010 to March 2021 was conducted using MEDLINE, EMBASE, and Cochrane databases to find studies relevant to EVAS. Search terms included “Nellix” OR “aneurysm sealing” OR “endovascular sealing” OR “sac sealing” OR “EVAS.” Related articles suggested by the PubMed search engine and reviews on this subject were searched for additional relevant articles. Further articles were also identified via examination of the references cited in the initially identified reports. The following data were extracted from each study: publication year, country of origin, reporting centers, study period, number of patients, age, gender, aneurysm anatomic properties, technical success, 30-day and follow-up outcome.

Quality assessment: The quality of observational studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies or cohort studies (as applicable).¹⁰ This tool evaluates 3 main methodological domains of cohort studies: (1) selection methods (representativeness of the exposed cohort, selection of the nonexposed cohort, ascertainment of exposure and demonstration that outcome of interest was not present at the start of the study), (2) comparability of cohorts on the basis of the design or analysis, and (3) assessment of outcomes (ascertainment of outcome, adequacy of follow-up). The scale uses a star system, with a maximum of 9 stars; studies achieving at least 6 stars were considered to be of higher quality.

Data synthesis and analysis: The outcomes were summarized as proportion incidence along with their 95% confidence intervals (CI), through a proportion meta-analysis. The inter-study heterogeneity was evaluated using the significance of the Cochran Q-metric (pQ) and quantified by the Higgins I² statistics. Significance was set at p<0.05, and we used continuity correction equal to 0.5 for metrics associated with zero events. The pooled estimate was assessed using the random-effects model in the presence of inter-study heterogeneity (I²>50%), or else with the fixed-effects model. We controlled for the presence of publication bias using 3 alternatives: (1) Fail-N Safe analysis, (2) rank correlation test for funnel plot asymmetry, and (3) Egger’s regression test. In the case of disagreement among the 3 tests, the existence of publication bias was assessed after eyeballing of the funnel plot. In addition, we controlled for differences in the duration of follow-up, using a regression meta-analysis. All statistical analyses were executed using the Jamovi project for the R-statistical environment.

Results

The initial search identified 760 articles potentially suitable for inclusion in the review (Figure 1). After exclusion of articles whose titles had no relevance to the topic or that were subsequent publications from the same institution, the full texts of 22 articles were retrieved and assessed for eligibility.^4,11–31 One article was excluded as not having detailed outcome data.¹⁹ Nine studies were excluded as a significant overlap with later studies from the same centers was evident.^17,20–27 The final analysis included 12 articles published between 2011 and 2021, which included a total of 1440 patients (median age 75 years; 91% men).^{4,11–16,18,28–31} The study cohorts ranged from 10 to 335 patients. All studies were observational and retrospective. Eight studies^{11,12,14,15,28–31} were single center and the remaining 4 were multicenter studies.^4,13,16,18 All 12 observational studies achieved a NOS score >6 (Table 2).

Table 2.

Studies’ Characteristics.

Author/Year	Hospital	Time period	NOS	Patients	Age	Males
Donayre et al.⁴	UCLA, Stanford, Riga, Auckland, Caracas, Cali	NR	8	21	69.7±8.3	19
Carpenter et al.³²	IDE trial (company funded) Portland, Indianapolis, Netherlands, Heidelberg	NR	8	150	NR	142
Gossetti et al.¹⁶	IRENE investigators (Rome, Turin, Modena, and Perugia, Italy), 16 Italian centers	2013–2015	8	335	75.5±7.4	316
Zerwes et al.¹⁵	Augsburg, Germany	2013–2015	8	100	72±8	89
Jeffrey Hing et al.¹⁴	Singapore	2014–2016	8	15	73±8	15
Zoethout et al.¹³	DEVASS Group_ Arnhem, Groningen, St Antonius, Tilburg	2013–2015	7	216	75	199
Najafi et al.¹¹	Canton Hospital Switzerland	2013–2016	8	10	75	8
Stenson et al.¹²	St George’s London	2013–2018	8	185	76±7.5	163
Yafawi et al.²⁸	Liverpool, UK	2013–2018	8	76	76±7.4	58
Singh et al.²⁹	Cambridge, London	2013–2017	8	161	78.4±7.1	140
Quaglino et al.³⁰	Turin, Italy	2013–2018	8	101	75±7.2	93
Hatzl et al.³¹	Heidelberg, Germany	2013–2018	8	70	72.5	67

Abbreviations: DEVASS, Dutch Endovascular Aneurysm Sealing Study; IDE, investigational device exemption; IRENE, Italian Research on Nellix Endoprosthesis; NOS, Newcastle-Ottawa Scale; NR, non-reported; UCLA, University of California, Los Angeles.

All aneurysms were treated with the same device (Nellix, Endologix Inc., Irvive, CA). Anatomic characteristics of the aneurysms treated are shown in Table 3. In total, 79.3% of the included patients had their aneurysm treated within the IFU for the Nellix device. Two studies (285 patients) compared the adherence of the patients treated within the 2013 and 2016 IFU.^11,12 Compliance with the 2013 IFU was observed in 58.2% (166/285) of the patients treated by EVAS, whereas compliance with the 2016 IFU was evident in only 23.9% (68/285) of the same cohort. The weighted mean maximum aneurysm diameter was 58.5mm. The weighted mean aortic neck diameter and length were 25.8mm and 25.2mm, respectively. The mean angulation of the aortic neck was 31.7°.

Table 3.

Aneurysm Characteristics.

Author/Year	AAA diameter (mm)	Neck length (mm)	Angulation (degree)	Neck diameter (mm)	2013 IFU	2016 IFU
Donayre et al.⁴	57±0.7	24.9±14.3	39±15	25.7±3.7	NA	NA
Carpenter et al.³²	58±6.2	31±14	30±14	25±3	150	NR
Gossetti et al.¹⁶	55.5±9.4	26.1±14.9	41.1±26.7	22.5±3.5	295	NR
Zerwes et al.¹⁵	NR	NR	NR	NR	75	34
Jeffrey Hing et al.¹⁴	64±16	29	42	22	11	NR
Zoethout et al.¹³	57.7 (54–62.7)	16 (9.8–30)	23 (12.5–35.6)	23.4 (24.4–26)	168	48
Najafi et al.¹¹	53.9±3.9	20.7±16	14.5	26±4.1	7	NR
Stenson et al.¹²	64.2±11.3	NR	NR	NR	91	34
Yafawi et al.²⁸	60 (54–93)	27 (6–65)	34 (0–78)	27±5	55	20
Singh et al.²⁹	78.4±7.1	65±10	NR	NR	NR	NR
Quaglino et al.³⁰	56 (53.6–60.8)	27 (15–34.5)	29.3 (19.8–40.35)	24 (14.7–26)	77	25
Hatzl et al.³¹	56 (39–82)	26 (2–79)	3 (30–61)	25 (17–36)	55	NR

Abbreviations: AAA, abdominal aortic aneurysm; IFU, instructions for use; IRENE, Italian Research on Nellix Endoprosthesis; NA, non-applicable; NR, non-reported.

30-Day Outcome

Detailed data on technical success were available in 11 studies (1255 patients).^{4,11,13–16,18,28–31} Technical success was achieved in 1241/1255 patients (98.8%). Technical failures included 7 proximal type I endoleaks, 2 aneurysm and 1 common iliac artery ruptures, and 2 accidentally covered renal arteries. Detailed data on 2 failures were missing.²⁹

Six studies (837 patients) reported the procedure time which ranged from 50 to 139 minutes.^4,13–16,18 The weighted mean procedure time was 97.16 minutes. The fluoroscopy time ranged from 10 to 33 minutes across only 2 studies (171 patients).^4,18

The 30-day complications are shown in Table 4. Overall 30-day mortality was 1.3%. Early procedure-related complications were reported in 58 patients (4%).

Follow-up

Overall: During a median follow-up period of 28.1 months (Table 5), ranging from 9 to 72 months, all 12 studies (1440 patients) provided detailed data on outcome. Τhe incidence of endoleak type I ranged from 1% to 50% and the pooled estimate was 16% (95% CI=7–25; heterogeneity: p<0.001, I²=97%, Figure 2A). Τhe incidence of migration ranged from 1% to 33% and the pooled estimate was 16% (95% CI=9–23; heterogeneity: p<0.001, I²=97%, Figure 2B). Aneurysm-related reintervention was reported with a rate ranging from 2% to 36% and a pooled estimate of 19% (95% CI=11–28; heterogeneity: p<0.001, I²=95%, Figure 2C). Τhe incidence of endograft thrombosis ranged from 0% to 11% and the pooled estimate was 1% (95% CI=0–2; heterogeneity: p=0.028, I²=30%, Figure 2D). Overall, 53 aneurysm-related deaths were reported during follow-up, with a mortality rate ranging from 1% to 11% across the studies. The pooled estimate for mortality during follow-up was 4% (95% CI=2–6; heterogeneity: p=0.03, I²=61%, Figure 2E). The length of follow-up did not affect the incidence of any from the above-studied outcomes, apart from aneurysmal death (Table 6). Even in this case, the effect estimate was minimal.

Table 4.

Thirty-Day Morbidity and Mortality Data.

	Number of patients (%)
Deaths	18 (1.3)
Groin hematoma	4 (0.2)
Limb occlusion	10 (0.7)
Paraparesis	2 (0.13)
Acute limb ischemia	12 (0.8)
Stroke	1 (0.07)
Pseudoaneurysm	2 (0.14)
Brachial embolization	1 (0.07)
Limb stenosis	1 (0.07)
Endoleak type II	2 (0.14)
Rupture	5 (0.35)
Respiratory failure	2 (0.14)
Reinterventions	17 (1.2)

Table 5.

Patients’ Outcome During Follow-up After EVAS.

	Overall follow-up (9–72 months)		Follow-up >2 years
	Range (%)	Pooled estimate	Range (%)	Pooled estimate
Endoleak type 1	1–50	16%	4–50	25%
Migration	1–33	16%	16–60	22%
Reintervention	2–36	19%	16–70	27%
Thrombosis	0–11	1%	1–11	2%
Aneurysm-related mortality	1–11	4%	1–11	6%

Table 6.

According to the Regression Analysis, the Duration of Follow-up Did Not Affect the Incidence of the Understudy Parameters, Except for Aneurysmal Deaths.

Outcome	Estimate	Lower	Upper	p
Endoleak I	0.003	−0.006	0.010	0.567
Endoleak II	5.84×10⁻⁴	−0.001	0.001	0.053
Migration	−1.22×10⁻⁴	−0.003	0.003	0.933
Thrombosis	4.54×10⁻⁴	−0.002	0.003	0.667
Reintervention	2.75×10⁻⁴	−0.005	0.005	0.915
Aneurysmal deaths	0.00158	0.0001	0.003	0.005

Follow-up more than 2 years: Seven studies (703 patients) reported outcome with a mean follow-up of more than 2 years (range 24–72 months).^{11,12,15,28–31} In these studies (Table 5), the incidence of endoleak type I ranged from 4% to 50% and the pooled estimate was 25% (95% CI=13–38; heterogeneity: p<0.001, I²=94.5%, Figure 3A). Τhe incidence of migration ranged from 16% to 60% and the pooled estimate was 22% (95% CI=19–26; heterogeneity: p<0.001, I²=93%, Figure 3B). Reintervention was reported with a rate ranging from 16% to 70% across 5 studies and a pooled estimate of 27% (95% CI=21–33; heterogeneity: p<0.001, I²=72%, Figure 3C). Τhe incidence of endograft thrombosis ranged from 1% to 11% and the pooled estimate was 2% (95% CI=0–4; heterogeneity: p=0.04, I²=59%, Figure 3D). The pooled estimate for aneurysm-related mortality was 6% (95% CI=3–9; heterogeneity: p<0.001, I²=67%, Figure 3E). Publication bias was detected in all analyses (Table 7).

Table 7.

Evidence of Publication Bias.

Outcome	k	Fail-safe N analysis	Rank correlation test	Regression test	Overall
Endoleak I	12	<0.001	0.197	<0.001	Yes
Endoleak II	12	<0.001	0.545	0.104	No
Migration	12	<0.001	0.250	<0.001	Yes
Thrombosis	12	<0.001	0.060	<0.001	Yes
Reintervention	12	<0.001	0.031	<0.001	Yes
Aneurysmal deaths	12	<0.001	0.250	<0.001	Yes

Follow-up comparative outcomes according to 2013 IFU vs 2016 IFU: Two studies compared the EVAS results based on IFU compliance. In total, 259 patients were treated according to 2013 and 82 patients according to the 2016 revised IFU. Compliance with either IFU did not appear to affect EVAS outcome during follow-up regarding reinterventions, endoleak type I, migration, sac expansion, and occlusions (Figure 4).

Discussion

The Achilles heel of EVAS is the long-term durability. Although initially reported results originating mostly from global registries were excellent, mid-term results showed worse outcomes. The present meta-analysis depicted that EVAS failure is more common than expected. Clearly, there is a significant risk for loss of proximal fixation zone as shown from the high migration and endoleak type I rates during follow-up. The postoperative surveillance of EVAS may be challenging and sac pressurization and device failure may occur in the absence of a visible endoleak.²⁷ The device lacks an active fixation mechanism, while unlike the self-expanding configuration of conventional EVAR devices, it cannot follow small changes of proximal aortic diameter. Even minor caudal movement of the device may lead to significant loss of aneurysm exclusion capability as the endobag polymer cast may no longer fit the aorta.

Another noteworthy finding is the timeframe during which EVAS failure was observed. Zerwes et al¹⁵ reported that the median interval to the “endoleak and/or migration” event was 29.3 months, whereas Stenson et al¹² confirmed this finding by reporting a high therapeutic failure occurring mostly 2 years and beyond after implantation. By isolating studies with a mean follow-up of more than 2 years, we found a higher pooled migration and reintervention rate (22% and 27%, respectively) when compared with the whole cohort (16% and 19%, respectively). Studies with a shorter than 2 years follow-up have demonstrated encouraging outcomes with very low morbidity and mortality and high procedural and treatment success. Thus, complication rates are likely to grow over time after the initial years and a meticulous long-term surveillance program with computed tomographic angiographies for all patients after EVAS is mandatory. Imaging features as stent migration, stent separation, or new thrombus formation should be investigated cautiously.

Two-year imaging revealed a significant rate of migration, leading to a field safety notification issued by the manufacturer in 2016, and a dedicated root cause analysis, resulting in refinements to the IFUs. The updated 2016 IFU significantly reduced the applicability of the Nellix device. While initially 58% of the patients had met the initial 2013 IFU, only 23% did so, according to the revised one; showing that this device seems not suitable for many AAA anatomies. The most important anatomic factor excluding patients from being inside IFU 2016 (that is not addressed in the IFU of conventional EVAR devices) was a thrombus ratio >1.4, restricting the use of the device to aneurysms with a small thrombus burden. In addition, the aorta diameter threshold was limited from 32mm to below 28mm, as the presence of a wide neck has been associated with a higher adverse neck-related event rate in standard EVAR.³³ Carpenter et al,³² by analyzing 2-year results of the investigational device exemption (IDE) pivotal trial, stratified according to 2016 and 2013 criteria, found significantly better results for the patients treated inside 2016 IFU. On the contrary, this meta-analysis found no significant difference in frequency of aneurysm-related complications when comparing IFU 2013 and 2016. Despite the limited data, provided by only 2 studies, this finding questions the effectiveness of the revised IFU in lowering device-related complications and improving survival. Long-term data, beyond 2 years, of all studies would be useful to be included in the future, to draw a definite conclusion. Recently, device manufacturer Endologix voluntarily recalled the existing inventory of its EVAS system after determining off-label use of the device had led to “suboptimal” results for patients. Nearly one-quarter (21.7%) of the EVAS patients included in this analysis were treated outside the IFU of the device. Based on current available data, it is not possible to determine long-term outcome when using the device solely inside the IFU.

The present meta-analysis raises important questions within the vascular community about the implementation and excitement for novel modalities. Innovation seems vital to advance the treatments that vascular surgeons can provide. However, novelty should not take precedence over vigorous safety and efficacy data. In 2016, the 30-day and 1-year safety results of the IDE trial of the Nellix device showed primary safety and effectiveness end point successfully achieved.^18,32 Oddly, in the same year, the IFUs for EVAS were refined due to higher than anticipated rates of implant displacement, endoleaks, and/or aneurysm enlargement, as the manufacturer suggested.³⁴ Only 2 years afterward, several studies reporting mid-term results showed a “more common than anticipated” failure of EVAS technique.²⁷ There are certain gray zones when evaluating a novel device for AAA treatment. The Nellix device had a CE mark, a proof that the company manufactures in compliance with minimum safety and health protection requirements for access to the European market. Proof of device safety and efficacy is usually grounded on relatively short-term outcomes such as 30-day or 1-year results. In the United States, new devices are also evaluated at 30 days and 1 year. Relevant initial reports of the Nellix showed that the device had met all the primary safety and efficacy endpoints.^18,32 It is not clear whether evaluating the efficiency of a device 1 year after implant is adequate for a device that may require long-term durability of more than 10 years in many patients. Long-term device specific performance should be published following EVAR and the authorities should retain a high index of alert in case of unfavorable outcomes by acting instantly. Currently, Endologix has completed enrollment in the EVAS2 Confirmatory Clinical Study, a novel study to evaluate the Nellix System. Furthermore, a new trial of the EVAS technique with parallel grafts for treating pararenal AAAs started recruiting patients (https://clinicaltrials.gov/ct2/show/NCT04252573). Results from both trials are anticipated.

Limitations

This meta-analysis included data across cohort studies to estimate the mid- and long-term outcome after EVAS. The main limitation of this review is that all articles included were nonrandomized observational studies and the methodologic quality of which varied considerably. While all series include consecutive group of patients treated with EVAS, infrarenal AAAs treated during the same study period were not treated exclusively with Nellix in each center, leading to a patient selection bias. Furthermore, many studies included data on the first cases performed and therefore reflects the learning curve and evolution of procedure. There is also a high heterogeneity rate in all outcomes. The follow-up ranged from 9 to 72 months, hence one would expect a much greater incidence of any such variables in studies with longer follow-up. However, data in the literature were not of sufficient quality to allow a time to event type of meta-analysis.

Conclusion

Patients who have been treated with EVAS are at high risk for reintervention especially beyond 2 years following implantation. Close surveillance for patients treated with EVAS is mandatory.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

G. Kouvelos

P. Nana

K. Spanos

P. Tasoudis

E. Verhoeven

References

Wanhainen

Verzini

Van Herzeele

, et al. Editor’s choice—European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms. Eur J Vasc Endovasc Surg. 2019;57(1):8–93.

United Kingdom EVAR Trial Investigators, Greenhalgh

Brown

, et al. Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med. 2010;362:1863–1871.

Kouvelos

Koutsoumpelis

Lazaris

, et al. Late open conversion after endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2015;61:1350–1356.

Donayre

Zarins

Krievins

, et al. Initial clinical experience with a sac-anchoring endoprosthesis for aortic aneurysm repair. J Vasc Surg. 2011;53(3):574–582.

Ockert

Heinrich

Kaufmann

, et al. Endovascular aortic sealing with Nellix reduces intraoperative radiation dose when compared to endovascular aortic repair. J Vasc Surg. 2018;67(4):1068–1073.

Karthikesalingam

Cobb

Khoury

, et al. The morphological applicability of a novel endovascular aneurysm sealing (EVAS) system (Nellix) in patients with abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2013;46:440–445.

Reijnen

de Bruin

Mathijssen

, et al. Global experience with the Nellix endosystem for ruptured and symptomatic abdominal aortic aneurysms. J Endovasc Ther. 2016;23(1):21–28.

Zerwes

Seduction and its impact on instructions for use. J Endovasc Ther. 2016;23(5):693–694.

Moher

Liberati

Tetzlaff

, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Int J Surg. 2010;8(5):336–341.

10.

Wells

Shea

O’Connell

, et al. The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-analyses. Ottawa Hospital/Research Institute. Accessed April 10, 2020. http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp.

11.

Najafi

Sheikh

Wigger

, et al. Outcome of Nellix-EVAS: single center mid-term results. CVIR Endovasc. 2019;2:13.

12.

Stenson

de Bruin

Loftus

, et al. Migration and sac expansion as modes of midterm therapeutic failure after endovascular aneurysm sealing. J Vasc Surg. 2020;71(2):457–469.

13.

Zoethout

Boersen

Heyligers

JMM

, et al; DEVASS (Dutch Endovascular Aneurysm Sealing Study) Group. Two-year outcomes of the Nellix endovascular aneurysm sealing system for treatment of abdominal aortic aneurysms. J Endovasc Ther. 2018;25(3):270–281.

14.

Jeffrey Hing

Ch’ng

Tay

, et al. Greater compliance within instruction for use for concomitant iliac aneurysms and adverse aneurysm characteristics-initial experience with the Nellix endovascular aneurysm sealing system at a single institution. Ann Vasc Surg. 2018;49:144–151.

15.

Zerwes

Bruijnen

Gosslau

, et al. Influence of the revised Nellix instructions for use on outcomes after endovascular aneurysm sealing. J Endovasc Ther. 2018;25(4):418–425.

16.

Gossetti

Martinelli

Ferri

, et al; IRENE Group Investigators. Preliminary results of endovascular aneurysm sealing from the multicenter Italian Research on Nellix Endoprosthesis (IRENE) study. J Vasc Surg. 2018;67(5):1397–1403.

17.

Karouki

Swaelens

Iazzolino

, et al. Clinical outcome after endovascular sealing of abdominal aortic aneurysms: a retrospective cohort study. Ann Vasc Surg. 2017;40:128–135.

18.

Carpenter

Cuff

Buckley

, et al; Nellix Investigators. One-year pivotal trial outcomes of the Nellix system for endovascular aneurysm sealing. J Vasc Surg. 2017;65(2):330–336.

19.

O’Donnell

TFX

Carpenter

Lane

3rd , et al. Endovascular aneurysm sealing is associated with higher medium-term survival than traditional EVAR. Ann Vasc Surg. 2020;63:145–154.

20.

England

Torella

Fisher

, et al. Migration of the Nellix endoprosthesis. J Vasc Surg. 2016;64:306–312.

21.

Brownrigg

de Bruin

Rossi

, et al. Endovascular aneurysm sealing for infrarenal abdominal aortic aneurysms: 30-day outcomes of 105 patients in a single centre. Eur J Vasc Endovasc Surg. 2015;50:157–164.

22.

Krievins

Holden

Savlovskis

, et al. EVAR using the Nellix Sac-anchoring endoprosthesis: treatment of favourable and adverse anatomy. Eur J Vasc Endovasc Surg. 2011;42(1):38–46.

23.

McWilliams

Fisher

England

, et al. Observations on surveillance imaging after endovascular sealing of abdominal aortic aneurysms with the Nellix system. J Endovasc Ther. 2015;22(3):303–306.

24.

Saitta

Gennai

Munari

, et al. New conception of relining in the endovascular aneurysm sealing era: a monocentric case series study. Ann Vasc Surg. 2019;56:351.e1–351.e7.

25.

Silingardi

Coppi

Ferrero

, et al. Midterm outcomes of the Nellix endovascular aneurysm sealing system: a dual-center experience. J Endovasc Ther. 2016;23(5):695–700.

26.

van Noort

Boersen

Zoethout

, et al. Anatomical predictors of endoleaks or migration after endovascular aneurysm sealing. J Endovasc Ther. 2018;25:719–725.

27.

Harrison

Winterbottom

Coughlin

, et al. Editor’s choice—Mid-term migration and device failure following endovascular aneurysm sealing with the Nellix stent graft system—a single centre experience. Eur J Vasc Endovasc Surg. 2018;56(3):342–348.

28.

Yafawi

McWilliams

Fisher

, et al. Aneurysm growth after endovascular sealing of abdominal aortic aneurysms (EVAS) with the Nellix endoprosthesis. Eur J Vasc Endovasc Surg. 2020;60(5):671–676.

29.

Singh

Benaragama

Pope

, et al. Progressive device failure at long term follow up of the Nellix EndoVascular Aneurysm Sealing (EVAS) System. Eur J Vasc Endovasc Surg. 2021;61:211–218.

30.

Quaglino

Mortola

Ferrero

, et al. Long-term failure after EVAS in a real-life single center experience with the Nellix endograft. J Vasc Surg. 2021;73(6):1958–1965.e1.

31.

Hatzl

Peters

Pfeiffer

, et al. Midterm single-center results after endovascular aneurysm sealing reveal a high rate of stent graft migration, secondary aneurysm ruptures, and device-related reinterventions. J Vasc Surg. 2021;74(3):738–745.

32.

Carpenter

Cuff

Buckley

, et al. 30-day results of the Nellix System IDE pivotal trial for endovascular aneurysm sealing. J Vasc Surg. 2016;63:23–31.

33.

Kouvelos

Spanos

Nana

, et al. Large diameter (≥29 mm) proximal aortic necks are associated with increased complication rates after endovascular repair for abdominal aortic aneurysm. Ann Vasc Surg. 2019;60:70–75.

34.

Endologix. Important field safety notice: updated instructions for use (IFU); 2016. Accessed April 28, 2022. https://endologix.com/wp-content/uploads/2017/09/Nellix-Field-Safety-Notice-Letter_Oct-10_2016-FINAL-2.pdf.