FDA panel advises curtailing use of AAA stent graft system due to type III endoleaks
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The FDA’s Circulatory System Devices Panel advised that for a stent graft system to treat patients with abdominal aortic aneurysms, the benefits outweigh the risks in niche populations, but not for routine use.
In an informal vote, approximately 70% of the panel said the benefits of the graft (AFX2, Endologix) outweighed the risks posed by type III endoleaks for use in niche and no-other-alternative situations, but less than 20% said that was the case for use in routine situations. Niche populations that may benefit from the device include women, patients with small vessels and patients with peripheral vascular disease, panel members said.
The AFX family of affected stent graft systems has been approved for use in the U.S. since 2011 and has been associated with type III endoleak at various points since then. The only AFX system currently marketed in the U.S. is the AFX2, which was approved in 2015. The panel was asked to advise the FDA on whether AFX2 should be allowed to stay on the market, and if so, whether labeling changes should be made and additional data should be collected.
Problems may persist
A company-sponsored trial with more favorable data than other studies “does not refute that there is an issue, given the duration of follow-up,” said panel member Joaquin E. Cigarroa, MD, chief of cardiovascular medicine at Oregon Health & Science University. “At least two of the three registry sets presented continue to identify a challenge. I believe the type III endoleaks pose a challenge to patients, and I have not seen enough data to assure me with a degree of certainty that that problem no longer persists.”
The task is to determine “how can certain controls be placed on this device that allow it to continue to [be accessed by] surgeons for specific populations, understanding that a more general use of the graft may pose increased risks,” said panel member Keith B. Allen, MD, director of cardiovascular/thoracic research and surgical co-director of the Structural Heart Program at St. Luke’s Mid America Heart & Vascular Institute.
In terms of additional steps, the panel would like to see trials and registries followed for more than 5 years, more data on niche populations be collected and annual imaging be conducted on patients who received the device, according to Richard A. Lange, MD, president and dean of the Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center and chair of the panel.
According to an executive summary written by FDA staff, several clinical reports have indicated that the design of the AFX systems may contribute to elevated risk for type III endoleak.
“The unattached PTFE (polytetrafluoroethylene) fabric can billow outward from the area in which the stent frame does not follow the aortic contour. This can occur in a tapered neck or in a dilated common iliac artery,” the FDA staff wrote in the executive summary. “Some literature reports describe billowing as a normal radiographic phenomenon, but others suggest that this finding may indicate an increased risk of aneurysm rupture.”
Data on endoleaks
In one study, among patients who had an Endologix stent graft, 16.8% had a type III endoleak, but among patients with comparator grafts, none did, the FDA staff wrote.
A second study showed a 24.3% type III endoleak rate in patients with early-generation AFX stent grafts, and a third study of a registry determined the type III endoleak rates were 16.5% for the AFX with Strata system, 9.6% for the AFX with Duraply system and 9.1% for the AFX2 system, according to the FDA summary.
The AFX with Strata system was recalled in 2016 to address type III endoleaks reported as early as 2013, and Endologix initiated another recall in 2018, according to the FDA summary. In the 2018 recall, the company reported it received reports of 535 serious or life-threatening injuries and 25 deaths associated with 544 complaints about the AFX systems from November 2016 to August 2018.
The FDA in December 2020 updated a safety communication about the AFX systems to state that rates of type III endoleak may be higher than expected for AFX with Duraply and AFX2, citing three more studies that were published in 2019 and 2020. The FDA also conducted a medical device report analysis showing at least 45% of medical device reports relating to the Endologix systems mentioned type III endoleak.
In 2015, Endologix began the LEOPARD trial of the AFX systems compared with endovascular aneurysm repair systems made by other manufacturers. In the most recent data from that trial, the cumulative probability of type III endoleaks for AFX devices was 1.3%, whereas there were no type III endoleaks associated with the other devices, according to the FDA summary.
In an analysis from the Vascular Quality Initiative registry, the AFX devices had a higher rate of type IIIa endoleaks but no difference in type IIIb endoleaks compared with devices from other manufacturers.
“Based on the limitations of Endologix’s data collection efforts and data available from other sources, it is unclear if mitigation strategies implemented by Endologix have solved the type III endoleak issue with the currently marketed AFX2,” the FDA staff wrote in the summary. “There is a known significant problem with the previous iteration of the device (the AFX with Strata that was recalled), and it is uncertain whether the device design/manufacturing changes and other mitigation measures have been adequate to address the type III endoleak issue in the currently marketed AFX2 device.”
In an executive summary submitted by Endologix, the company wrote: “The current post-product update population (which includes lifetime data for the AFX2 system), has a reported event rate of 0.8% at 4 years, which is half the rate reported in the literature for non-AFX devices.”
In a presentation, Endologix argued that most data cited by the FDA were from small, retrospective studies and did not pertain to AFX2, and that AFX2’s performance is similar to other commercially available endoscopic aneurysm repair grafts.
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