Twenty years after its introduction, the role of endovascular aortic aneurysm repair (EVAR) in the management of abdominal aortic aneurysms (AAAs) continues to increase. This progress was only possible thanks to the development of new stent grafts and delivery systems enabling us to perform EVAR in patients with shorter and more angulated necks, smaller and more tortuous iliacs, and overall more challenging anatomies. Insights obtained from analysis of the failure modes for previous devices led to the development of more flexible and conformable grafts and delivery systems with smaller diameters and more trackability.

Experience with the first generation of endografts also taught us to be cautious about the short- and long-term performance of these devices with regard to migration, integrity, modular disconnection, kinking, thrombosis, and late endoleaks and ruptures. Therefore, it is important to conduct thorough surveillance of implanted endografts not only in the early stages of their use, but also over the long term, and to carefully analyze the data collected. This article provides an overview of the main studies that have evaluated the Endurant® stent graft (Medtronic, Inc., Minneapolis, MN).

TRIAL RESULTS OVERVIEW

Endurant has demonstrated consistently successful clinical performance across both well-controlled trials and real-world registries, in a variety of patient types and anatomies.

Prospective European Trial

The Prospective European Trial of the Endurant Stent Graft for Abdominal Aortic Aneurysm Repair (EU-trial)1 was a prospective, single-arm, nonrandomized, multicenter trial including 80 elective patients treated in 10 European hospitals. The trial was designed to assess the clinical safety and performance of the endograft during the first year after implantation. Morphological inclusion criteria needed to be consistent with the Endurant instructions for use.

The device was successfully delivered and deployed in all cases. Only 5% needed a blood transfusion. The 30-day mortality rate was 2.5%, but none of these deaths were considered as procedure or device related. Overall, 28 endoleaks (26 type II, 2 undefined) were identified. Throughout the 1-year follow-up period, there were no type I or III endoleaks and no loss of device integrity. There was no graft migration, no conversion to open repair, and no AAA rupture. Limb thrombosis occurred in three patients but required reintervention in only one. A total of three out of 80 patients had secondary interventions, all endovascular, to address one occlusion, one stenosis, and one procedure to extend the distal landing zone. During follow-up, two more patients died, providing a survival rate of 95% after 1 year. In only two patients a further aneurysm expansion ≥ 5 mm was observed. Both had a type II endoleak from the inferior mesenteric and lumbar arteries. A decrease of > 5 mm was seen in 43% (32/75) of the patients.

United States Regulatory Trial

The United States regulatory trial2 was a prospective, single-arm, multicenter trial conducted in 26 sites in the United States and included 150 patients with AAA diameters > 5 cm, a proximal neck ≥ 10 mm, bilateral iliac landing zones ≥ 15 mm, and neck angulation ≤ 60°. The vast majority of the interventions (83%) were performed under general anesthesia. Stent graft implantation was technically successful in 99.3% (149/150). The failure was due to the inability to cannulate the contralateral gate. The problem was solved by conversion to an aorto-uni-iliac endograft with femorofemoral bypass. One patient had a neck rupture during ballooning but could still be treated successfully. Blood transfusion was required in only one patient (0.7%). Five supplementary interventions were performed during the first month, all for arterial events and all using open techniques. There was no 30-day mortality. At 1-month follow-up, endoleaks (all type II) were present in 23/143 (16%) of patients.

Through the first year of follow-up, there were no migrations, no conversions to open repair, and no ruptures. Thirteen (10%) endoleaks were found at 1 year (12 type II, 1 indeterminate). No type I or III endoleaks were identified during this first year, although one type II endoleak later proved to be a type Ib on angiography and was treated with an extension. Ten (6.7%) reinterventions were performed during the first year: four endovascular and six open. Three of these interventions were for vascular problems related to the procedure, two for the treatment of type II endoleaks (without sac enlargement), and five because of limb stenosis or occlusion. Most of these were due to compression in a small aorta or kinked iliac arteries.

Aneurysm sac diameter decreased > 5 mm at 1 year in 47% of patients and remained stable in 53%. No sac showed an increase > 5 mm.

United States Trial at 2 Years

Endurant has demonstrated consistent clinical results at 2 years.3 There were no type I endoleaks, migration, conversion to surgery, aneurysm-related mortality, and postoperative ruptures. Aneurysm sac diameter either decreased or remained stable in 98.3% of patients. In the second year, an additional 1.4% of patients required a second intervention (Data on file at Medtronic, Inc.). Stent graft integrity was 100%.3 These results show that at midterm follow-up (2 years), when following the instructions for use, clinical outcomes with the Endurant endograft remain excellent.

ENGAGE Registry

Trials undertaken for regulatory purposes have stringent inclusion criteria, providing the advantage of a clearly defined and homogenous study population. The disadvantage is that they often do not reflect realworld practice, and the outcomes may not be applicable to the general population.4

ENGAGE (Endurant Stent Graft Natural Selection Global Postmarket Registry) is a long-term, worldwide, prospective real-world postmarket study evaluating the Endurant stent graft.5 ENGAGE was designed to increase the knowledge base about EVAR in a complex real-world population with the use of a single, latestgeneration endograft. In total, 1,262 patients were included, which makes this study the largest real-world registry for any single endograft. The implantation of the device was successful in 99.5% of patients. The allcause mortality rate at 30 days was 1.3%. One-year follow- up is available on the first 500 patients and showed no migrations, no ruptures, and 0.6% conversions. Only one (0.2%) aneurysm-related death occurred after the 30-day period, yielding an aneurysm-related mortality rate of 1.4% at 1 year. The rate of secondary procedures to correct type I/III endoleak at 1 year was 1.2%, and the overall rate of secondary procedures was 4.6%. At 1 year, type II endoleaks were present in 8% of patients.

DISCUSSION

Although it only became commercially available in 2008, the Endurant stent graft is already one of the best characterized endografts in current use, supported by a rigorous body of clinical evidence. Pivotal trials, single-center series, and a global registry all show very consistent results. The technical success rate in patients treated according to the morphological IFU is consistently above 99%. One-year data from the ENGAGE registry showed no type I or type IV endoleaks and no aneurysm ruptures.5 There were no graft migrations and only three late conversions to open repair. Secondary vascular procedures were performed in 4.9% of the patients.5 The majority of these were performed for vascular access complications. Endurant has continued to demonstrate excellent clinical outcomes, and physicians are confident in the performance of the device.5

The clinical outcomes for Endurant—including type I/III endoleaks, conversion rates, and migration rates— are all consistently and significantly lower than what was demonstrated in older trials, such as EVAR-1 and DREAM,6,7 as well as the Eurostar and Lifeline registries. Similarly, the first-year reintervention rate is cut by 50% to 75% in the trials evaluating Endurant, as compared to the reintervention rates achieved in EVAR-1 and DREAM. The consistently successful clinical outcomes achieved by Endurant—across a variety of studies and various anatomies—illustrates the translation of proven endograft design concepts into excellent clinical outcomes.

CONCLUSION

The aggregated published clinical evidence highlights the consistent clinical outcomes of the Endurant stent graft system.1-4 In several studies and a real-world registry (ENGAGE), the device has consistently shown to be safe and effective, with excellent technical success rates, freedom from type I/III endoleaks, and freedom from conversion.

Frank Vermassen, MD, PhD, is with the Department of Vascular Surgery at Ghent University Hospital in Ghent, Belgium. He has disclosed that he has participated in clinical trials for Medtronic. Dr. Vermassen may be reached at frank.vermassen@ugent.be.

Nathalie Moreels, MD, is with the Department of Vascular Surgery at Ghent University Hospital in Ghent, Belgium. She has disclosed that she has no financial interests related to this article.

  1. Rouwet EV, Torsello G, de Vries JP, et al. Final results of the prospective European trial of the Endurant stent graft for endovascular abdominal aortic aneurysm repair. Eur J Vasc Endovasc Surg. 2011;42:489-497.
  2. Makaroun MS, Tuchek M, Massop D, et al; Endurant US Pivotal Trial Investigators. One year outcomes of the United States regulatory trial of the Endurant stent graft system. J Vasc Surg. 2011;54:601-608.
  3. Endurant 2011 Annual Physician Clinical Update. Site-reported data.
  4. Böckler D, Riambau V, Fitridge R, et al. Worldwide experience with the Endurant stent graft system: Review of the literature. J Cardiovasc Surg 2011; 52:669-681
  5. Riambau V, on behalf of Engage investigators. Are contemporary results with EVAR better than in the past? Results from Engage global registry. Presented at: Leipzig Interventional Course (LINC); January 2012; Leipzig, Germany. Data on file at Medtronic, Inc.
  6. The United Kingdom EVAR Trial Investigators. Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med. 2010;362:1863-1871.
  7. De Bruin J, Baas A, Buth J, et al, for the DREAM study group. Long-term outcome of open or endovascular repair of abdominal aortic aneurysm. N Engl J Med. 2010;362:1881-1889.