Endovascular Aneurysm Sealing is Associated with Higher Medium-Term Survival than Traditional EVAR

Abstract

Endovascular repair (EVAR) is the dominant treatment modality for abdominal aortic aneurysm (AAA). Periprocedural risks are low, and cardiovascular events are the principle determinants of long-term survival. Recently, the concept of endovascular aneurysm sealing (EVAS) has been introduced into clinical investigation. In previous cohort studies EVAS has been associated with a lower all-cause mortality than expected despite device issues. We used a propensity weighted approach to investigate whether EVAS was associated with lower all-cause mortality after aneurysm repair. We compared the 333 patients in the Nellix United States Investigational Device Exemption (IDE) to 15,431 controls from the Vascular Quality Initiative (VQI) between 2014-2016 after applying the exclusion criteria from the IDE (hemodialysis, creatinine > 2.0 mg/dL, or rupture). We calculated propensity scores and applied inverse probability weighting to compare risk adjusted medium-term survival using Kaplan-Meier and Cox regression. After weighting, patients treated with the Nellix EVAS system experienced higher three-year survival than controls from the VQI (93% vs 88% respectively). This corresponded to a 41% lower risk of mortality for EVAS compared to EVAR (HR 0.59 [0.38 – 0.92], P = 0.02). Subgroup analysis demonstrated that the association between EVAS and higher survival was strongest in the subgroup of patients with aneurysms over 5.5 cm (P for interaction < .001). In this subgroup, EVAS patients experienced half the rate of mortality as those patients treated with EVAR, with three-year survival of 92% compared to 86% (HR 0.5 [0.3 – 0.9], P = 0.02). In this select group of patients, EVAS was associated with higher medium-term survival than traditional EVAR. Although issues with the device have recently surfaced, this exploratory analysis shows that the concept of sac sealing may hold promise. Further study is needed to confirm this finding and determine whether EVAS is associated with lower rates of cardiovascular events.