Late EVAR Failures With Early-Generation Grafts Highlight Need for Lifelong Surveillance

The survival benefit of endovascular aortic aneurysm repair (EVAR) over open surgery for large abdominal aortic aneurysm (AAA) appears to disappear over long-term follow-up, leaving both approaches with similar total and aneurysm-related mortality, new data suggest. With more than a decade of follow-up, a multicenter trial conducted in the United Kingdom shows that secondary aneurysm sac rupture is a common contributor of late mortality after EVAR.

“Challenges in the future to maintain the initially better results of being in the EVAR group include the need to halt the dilating disease process as well as devices that allow for this inevitable dilating process over the years,” write Rajesh Patel, PhD (Imperial College London, England), and colleagues.

The study, known as EVAR trial 1, followed patients for nearly 16 years (mean 12.7 years). According to the study authors, the results “can act as a benchmark against which new endovascular technologies for aneurysm repair can be compared with at each time point.”

More importantly, from a patient perspective the findings highlight the importance of “lifelong surveillance of EVAR and prompt reintervention if necessary,” they note.

Published online October 12, 2016, ahead of print in the Lancet, the study followed 1,252 patients with aneurysms of at least 5.5 cm in diameter who were eligible for either EVAR or open repair and were randomized and treated from September 1999 through August 2004. Patients treated with EVAR received a median of six CT scans during follow-up as mandated by the protocol.

Compared with the surgery group, those who had EVAR had lower total mortality (adjusted HR 0.61; 95% CI 0.37-1.02) and aneurysm-related mortality (adjusted HR 0.47; 95% CI 0.23-0.93) in the first 6 months after treatment. However, beyond 8 years the curves diverged, with the EVAR group having higher total mortality (adjusted HR 1.25; 95% CI 1.00-1.56) and aneurysm-related mortality (adjusted HR 5.82; 95% CI 1.64-20.65). The latter was primarily driven by more cases of secondary sac ruptures in the EVAR group than in the surgery group (13 vs 2).

Improvements Made Since Study Era

In an accompanying editorial, Isabelle Van Herzeele, MD, and Frank Vermassen, MD, PhD (both Ghent University Hospital, Ghent, Belgium), note that much has changed in the management of AAA since the patients in the study were treated more than a decade ago.

“Case selection, device choice, and planning with technical skills by use of simulation, imaging modalities with decreased radiation, best practices in medical treatment, and surveillance programs in centralized aortic units have all improved the overall management of aortic aneurysmal disease,” they write.

Van Herzeele and Vermassen say more research is needed to understand the late secondary ruptures, which could be the result of aneurysm growth or rupture caused by true device failures such as fractures, migration, or endoleak type I or III. Another possibility is that the initial stent graft was not deployed within 3 mm of the lowest renal artery, they suggest.

The editorialists also question whether surveillance was long enough and whether serious and life-threatening complications were managed appropriately by secondary interventions.

CT-Related Cancer From EVAR Surveillance?

Another potentially important question has to do with cancer mortality, which was greater in the EVAR group but only briefly mentioned in the paper, Christopher K. Zarins, MD (Stanford University Medical Center, Stanford, CA), who was not involved in the study, told TCTMD.

Although similar percentages of patients in both groups died of lung cancer, 21% of patients in the EVAR group died of “other” cancer compared with 14% in the surgery group. Zarins said the amount of radiation given to patients in the EVAR group for their follow-up CTs is an open question that needs to be addressed.

“[The authors] never discuss that, but it would be good to calculate it and see what the radiation dose is for lifelong surveillance in these patients,” Zarins said, adding that ultrasound likely would be preferred outside of a trial setting to follow aneurysm size.

In their editorial, Van Herzeele and Vermassen agree that more investigation into the matter is needed but caution that “any insinuation that EVAR predisposes to or increases the risk of cancer might be dangerously misleading.”

The bottom line regarding EVAR in these patients, noted Zarins, “is that you’re trading off reduced periprocedural early mortality for the risks of late complications of the device and perhaps less long-term device security. These [were] early-generation devices, though, and we don’t know if late device failures will happen with current devices. But they could, because it all comes down to time and aging. These are pertinent issues that make the point that you need to consider everything in your treatment choice, and an EVAR is not necessarily a lifelong guarantee.”

Sources
  • Patel R, Sweeting MJ, Powell JT, et al. Endovascular versus open repair of abdominal aortic aneurysm in 15-years’ follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. Lancet. 2016;Epub ahead of print.

  • Van Herzeele I, Vermassen F. Selection, technique, and follow-up: keys to success in EVAR. Lancet. 2016;Epub ahead of print.

Disclosures
  • Patel and Zarins report no relevant conflicts of interest. Van Herzeele reports serving as an adviser for Medtronic Academia and Silk Road Medical, and receiving research grants from Medtronic Academia, Simbionix, and W L Gore.
  • Vermassen reports consulting for Bloomingdale, Cook, Medtronic, and W L Gore.

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