Structured CT analysis can identify the majority of patients at risk of post-EVAR rupture

Abstract

Objectives

The main objective was to report mechanisms and precursors for post-EVAR rupture. The second was to apply a structured protocol to explore if these factors were identifiable on follow-up CT prior to rupture. The third to study incidence, treatment and outcome of post-EVAR rupture.

Design

Multi-center, retrospective.

Materials

Patients treated with standard EVAR at five Swedish hospitals 2008-2018.

Methods

Patients were identified in the Swedvasc registry. Medical records were reviewed until 2020. Data of index EVAR and follow-up were recorded. The primary endpoint was post-EVAR rupture. CT at follow-up and at post-EVAR rupture were studied, using a structured protocol, to determine rupture mechanisms and identifiable precursors.

Results

In 1805 patients treated with EVAR, 45 post-EVAR ruptures occurred in 43 patients. The cumulative incidence was 2.5% over a mean follow-up of 5.2 years. The incidence rate was 4.5/1000 person years. Median time to post-EVAR rupture was 4.1 years. Another 6 cases of post-EVAR rupture in 5 patients found outside the main cohort were included in the analysis of rupture mechanisms only. The rupture mechanism was type IA in 20/51 cases (39%), IB in 20/51 (39%), and IIIA/B in 11/51 (22%). One of these had type IA+IB combined. One patient had aorto-duodenal fistula without other mechanism identified. Precursors had been noted on CT follow-up prior to post-EVAR rupture in 16/51 (31%). Retrospectively, using the structured protocol, precursors could be identified in 43/51 (84%). In 17/27 (63%) of cases missed on follow-up but retrospectively identifiable the mechanisms were type IB/III. Overall, 30-day mortality following post-EVAR rupture was 24/51 (47%) and post-operative mortality 7/33 (21%).

Conclusions

Most precursors of post-EVAR rupture are underdiagnosed, but identifiable before rupture using a structured follow-up CT protocol. Precursors of type IB and III failures caused the majority of post EVAR ruptures.