Editor's Choice - Structured Computed Tomography Analysis can Identify the Majority of Patients at Risk of Post-Endovascular Aortic Repair Rupture

Objective: The main objective was to report mechanisms and precursors for post-endovascular aneurysm repair (EVAR) rupture. The second was to apply a structured protocol to explore whether these factors were identifiable on follow up computed tomography (CT) prior to rupture. The third objective was to study the incidence, treatment, and outcome of post-EVAR rupture. Methods: This was a multicentre, retrospective study of patients treated with standard EVAR at five Swedish hospitals from 2008 to 2018. Patients were identified from the Swedvasc registry. Medical records were reviewed up to 2020. Index EVAR and follow up data 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 1 805 patients treated by 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 4.5/1 000 person years. Median time to post-EVAR rupture was 4.1 years. A further six cases of post-EVAR rupture in five patients found outside the main cohort were included in the analysis of rupture mechanisms only. The rupture mechanism was type IA in 20 of 51 cases (39%), IB in 20 of 51 (39%) and IIIA/B in 11 of 51 (22%). One of these had type IA + IB combined. One patient had an aortoduodenal fistula without another mechanism being identified. Precursors had been noted on CT follow up prior to post-EVAR rupture in 16 of 51 (31%). Retrospectively, using the structured protocol, precursors could be identified in 43 of 51 (84%). In 17 of 27 (63%) cases missed on follow up but retrospectively identifiable, the mechanisms were type IB/III. Overall, the 30 day mortality rate after post-EVAR rupture was 47% (n = 24/51) and the post-operative mortality rate was 21% (n = 7/33). 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.