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April 24, 2020

Medtronic’s Endurant Stent Graft Evaluated in Real-World Experience Treating 180 Patients With AAA

April 24, 2020—Findings from a large, single–vascular unit experience using the Endurant stent graft (Medtronic) in consecutive patients treated between August 2008 and March 2019 were recently published online by Glen L. Benveniste, MBBS, et al in Annals of Vascular Surgery.

The aim of this study is to report results using methods to ensure complete ascertainment of mortality from a large, real-world experience with the Endurant device at Prince of Wales Hospital in Sydney, New South Wales, Australia. The background is that registry studies have shown that the Endurant stent graft is associated with low rates of all-cause and aneurysm-related mortality when used for the endovascular treatment of abdominal aortic aneurysm (AAA). However, many studies were limited by length of follow-up, and all had a proportion of patients lost to follow-up.

As summarized in Annals of Vascular Surgery, the study included 180 patients (mean age, 76 ± 8.6 years; 90% male) with a mean AAA diameter of 57.5 ± 10.5 mm treated with endovascular aneurysm repair (EVAR). Technical success was achieved in all cases.

The investigators reported the following:

  • Of 180 patients, 28.3% (n = 51) had died at median follow-up of 55 months (interquartile range, 29.8–79).
  • Overall survival was 71.6% per Kaplan-Meier estimate at 5 years.
  • Overall freedom from aneurysm-related death was 99.4% per Kaplan-Meier estimate at 5 years.
  • Lower survival rates were observed in patients who underwent EVAR at age ≥ 80 years (59.2% vs 78.3%; P < .01) and with aneurysm diameter ≥ 70 mm (55.6% vs 73.8%; P = .03).

Additionally, the investigators observed:

  • Thirteen endoleaks (7.2%) during follow-up (mean time from implantation, 8.7 ± 4.2; range, 1–52 months).
  • Four endoleaks were type 1A, two were type 1B, seven were type 2.
  • Eleven patients (6.1%) required secondary intervention: seven for limb occlusion, three for endoleak, and one for restenosis.

Finally, patients treated within the manufacturer’s instructions for use (IFU; n = 104; 57.8%) and outside the IFU (n = 76; 42.2%) had similar rates of the following outcomes:

  • Endoleak (6.7% vs 7.9%; P = .76)
  • Secondary reintervention (6.7% vs 5.3%; P = .74)
  • Overall survival (69.2% vs 72.3%; P = .46)

In their conclusions in Annals of Vascular Surgery, the investigators stated, “Results from this real-world study of consecutive patients treated for AAA using the Endurant stent graft demonstrate that it is safe and effective, with excellent long-term outcomes for anatomy that falls both inside and outside IFU recommendations.”

Summarizing the study to Endovascular Today, investigator Ramon L. Varcoe, MBBS, said, “It is one of the largest series in the international literature and it used data-linkage methodology to remove the ascertainment bias that typically plagues studies of this type. Data-linkage not only ensures that no patient is lost to follow-up when it comes to the assessment of all-cause mortality but also records an accurate cause of death from autopsy, which enables us to determine aneurysm related death wherever possible. This is the only study in the published literature to have used this methodology, and this makes it unique to the field.”

Prof. Varcoe continued, “Furthermore, it has the longest median follow-up in the published literature for this EVAR device. This is particularly relevant given the recent long-term results from randomized clinical trials (using a variety of first-generation endografts), which suggest a late catch-up effect in all-cause mortality after EVAR compared to open surgery. Finally, it compared results for patients treated with both straightforward and complex anatomical variations, finding no difference in outcomes for patients on and off IFU—again, providing novel findings that suggest that current-generation endografts may not be as challenged by complex anatomies as those less sophisticated/older devices.

“Historically it has been considered that doing EVAR in anatomy that falls outside IFU was high risk and led to poorer outcomes. We didn’t observe this, which may reflect the sophistication and adaptability of the current generation stent graft device we used in the study,” added Prof. Varcoe. “There has been a lot of talk about ascertainment bias in peripheral artery disease trials, but it has been largely overlooked in EVAR studies. We think that it is an important factor, as missing data is common in long-term trial follow-up. When you are investigating mortality, data-linkage is an excellent tool to eliminate that bias, and in our view should be used more often.”

Prof. Varcoe is Senior Vascular Surgeon, Prince of Wales Hospital; Director, The Vascular Institute, Prince of Wales; and Associate Professor of Vascular Surgery, University of New South Wales.

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