Results from a real-world experience over more than 10 years using the Endurant stent graft (Medtronic) demonstrate that it is safe and effective, with excellent long-term outcomes for abdominal aortic aneurysm (AAA) anatomy that falls both inside and outside instructions for use (IFU) recommendations. These findings were recently published online in Annals of Vascular Surgery.
The investigators, Glen L Benveniste, MBBS, of Ashford Vascular Clinic, Adelaide, Australia, and colleagues—including Ramon Varcoe, MBBS, of Prince of Wales Hospital, Sydney, Australia—acknowledge that registry studies have shown the Endurant stent graft to be associated with low rates of all-cause and aneurysm-related mortality when used for the endovascular treatment of AAA. However, many were limited by length of follow-up and all had a proportion of patients lost to follow-up.
Therefore, the aim of the present study was to report results from a large, real-world experience using Endurant, utilizing methods to ensure complete ascertainment of mortality. This study describes a large, single vascular unit experience using the Endurant stent graft in consecutive patients treated between August 2008 and March 2019.
Benveniste et al note that 180 patients included in the study (mean age 76±8.6 years; 90% male) with mean AAA diameter of 57.5±10.5mm underwent endovascular aneurysm repair (EVAR).
The authors report the following results:
- Technical success was achieved in all cases
- At median follow-up of 55 months (interquartile range 29.8–79), 51 (28.3%) patients had died
- A Kaplan-Meier estimate of five-year overall survival and freedom from aneurysm-related death was 71.6% and 99.4%, respectively
- Lower survival rates were observed in patients who underwent EVAR age ≥80 years (59.2% vs. 78.3%, p<0.01) and with aneurysm diameter ≥70mm (55.6% vs. 73.8%, p=0.03)
- Thirteen endoleaks (7.2%; four type 1A, two type 1B, seven type 2) were observed during follow-up (mean time from implantation 8.7±4.2, range 1–52 months)
- Eleven patients (6.1%) required secondary intervention for limb occlusion (n=7), endoleak (n=3), and restenosis (n=1)
- Patients treated within (n=104; 57.8%) and outside (n=76; 42.2%) the manufacturer’s IFU had similar rates of endoleak (7 [6.7%] vs. 6 [7.9%]; p=0.46)
Benveniste and colleagues remark that the early benefits of EVAR are well documented, with randomized trials demonstrating lower perioperative mortality risk than the alternative of open surgical repair. They add, however, that during long-term follow-up, this advantage may be reduced due to increased late mortality in the EVAR group.
“Although this phenomenon is likely to be multifactorial, a major contribution is thought to be the early generation of stent grafts used in those initial randomized trials,” they suggest. “Those first-generation devices are known to be less durable, experiencing higher rates of late aneurysm sac rupture, aneurysm-related mortality, endoleak, migration, and secondary reintervention when compared to contemporary stent-graft systems.”
In this context, the authors explain their choice of the Endurant stent graft: “We chose the Endurant stent graft following a broader experience with multiple alternative, first- and second-generation devices. As our experience grew with that device, we preferentially chose it due to its ease of use, low-profile delivery system, controlled stage deployment, conformability, and suprarenal stent. Those features provide accurate placement, active fixation, and facilitate graft placement into patients with calcified, stenotic iliac arteries and cases where anatomy fell outside the IFU.”
Benveniste et al note that previous studies have evaluated long-term outcomes with the Endurant stent graft. Commenting on the position of this study in relation to other published works, they write: “This study complements the existing literature with a further large real-world registry that demonstrates the long-term durability of the Endurant stent-graft device and adds to it further by introducing death registry data linkage to reduce bias.”
The investigators acknowledge several limitations of the present study, the first being that it is a single-arm, single-device, observational study with no control group for comparison. “Therefore,” they remark, “no direct analysis can be conducted against open surgery or other types of stent graft.”
Also, the subgroup analyses of age, anatomical compliance with IFU, and aneurysm diameter were not randomized and “will certainly be predisposed to selection bias”.
Finally, the follow-up imaging was conducted using duplex ultrasound, with selective use of CT scanning. “Ultrasound is known to be less sensitive than CT which may have introduced bias in aneurysm sac measurements and under detection of endoleak; however, this approach is now commonplace in experienced vascular unity where it is used to avoid cumulative radiation exposure, iodinated contrast, and cost.”
Speaking to Vascular News, Varcoe commented: “This study is one of the longest in the international literature to have evaluated the Endurant stent-graft system. It demonstrated excellent freedom from all-cause mortality and no difference between anatomical variations which fell within- and outside-IFU recommendations.”
He continued: “This study was unique in that it used data-linkage techniques to reduce the risk of missing mortality events in patients who were lost to follow up. We think this is an important methodology for long term aortic aneurysm studies and we are currently in the process of applying it to a much larger Australian dataset as part of ongoing research.”