Study Evaluates Long-Term Survival Rates of Endologix's Nellix EVAS System Compared With EVAR

April 25, 2018—Endologix, Inc. announced the results of a retrospective, propensity-weighted study of long-term survival using the company's Nellix endovascular aneurysm sealing (EVAS) system compared with traditional endovascular aneurysm repair (EVAR) in the treatment of abdominal aortic aneurysms (AAAs). Marc Schermerhorn, MD, presented the findings in the late-breaking aortic trials session at the Charing Cross international symposium held April 24–27 in London, United Kingdom.

The study demonstrated significantly higher 3-year survival rates for EVAS patients. Those with larger aneurysms treated with EVAS had half the mortality at 3 years compared to those treated with EVAR systems.

According to Endologix, the retrospective study included 333 EVAS patients from the original Nellix United States investigational device exemption (IDE) trial and 15,431 EVAR patients from the Society for Vascular Surgery Vascular Quality Initiative, all of whom were treated between 2014 and 2016.

The patients were propensity weighted for AAA size, patient demographics, and cardiovascular risk factors. The primary outcome was overall survival, with a secondary analysis of overall survival stratified by aneurysm size.

EVAS patients experienced higher 3-year survival than EVAR patients (93% vs 88%; P = .02), which corresponded to a 41% lower risk of mortality with EVAS. In patients with larger aneurysms (> 5.5 cm in diameter), patients treated with EVAS had a 50% lower mortality rate than patients treated with EVAR (P = .02).

In the company's announcement, Dr. Schermerhorn commented, “The study sought to examine two different therapies for treating AAA and compare the associated mortality. Traditional EVAR excludes the aneurysm sac and has been associated with thrombus generation, sac remodeling, inflammation, and endoleaks, while EVAS excludes and seals the entire aneurysm sac.”

Dr. Schermerhorn continued, “The survival difference seen in this study supports the continued development of EVAS therapy and demonstrates its potential to improve patient outcomes. The results also justify further study to compare cardiovascular events between the two therapies in order to understand the mechanism behind the events.”

The company noted that in earlier Nellix EVAS studies, all-cause and cardiovascular mortality were lower than expected, and this propensity-weighted analysis is the first contemporary comparison of the data.

The data that serve as the basis for this analysis include patients under the original Nellix instructions for use (IFU) criteria, and the analysis has not been reviewed by the US Food and Drug Administration.

Endologix advised that since completion of the original 333-patient Nellix IDE trial, the IFU for the device were refined to improve aneurysm-related outcomes. In March 2018, Endologix initiated the EVAS2 confirmatory IDE trial to evaluate the safety and effectiveness of the refined IFU together with the next-generation Nellix EVAS system.

The Nellix EVAS system is an investigational device in the United States and is limited by federal law to investigational use only, stated the company.