Modifierbara faktorer associerade till post-EVAR ruptur. Can post-EVAR rupture be prevented

Abstract

Background: Endovascular aortic repair has better short-term survival than open surgical repair but this advantage is lost over time. The main cause is rupture after EVAR. Its incidence has not decreased despite efforts of current follow-up. The aim was to study causes of post-EVAR rupture, possible precursors and associations to early imaging findings, potentially improving EVAR outcome. Methods: All studies are retrospective. Study 1 include all patients treated for an abdominal aortic aneurysm in Sweden 2001-2015 using national registries. Study 2-4 are based on a cohort of 1805 consecutive patients treated with EVAR 2008-2018. Patients were identified in Swedvasc, and medical records reviewed. Pre- and postoperative CTs were reviewed using a structured protocol. In study 2 mechanisms and warning signs of post-EVAR rupture were studied in a cohort of 1805 patients. In study 3 the incidence of loss of seal was analyzed in 399 consecutive patients. In study 4, association between loss of seal and early CT findings was studied in 454 patients. Results: In study 1, the incidence of rupture after EVAR was 3.4/1000 person years, with no decline during the study period. The 30-day mortality was 42%. In study 2 the mechanism of rupture was a loss of seal leading to an endoleak in the proximal (39%) or distal (39%) sealing zones or between components (22%). Structured CT review increased the detection rate of loss of seal from 31% to 84% compared to clinical follow-up. In study 3, total or partial loss of seal affected 85 (21%) and 78 (20%) patients, most often due to vessel dilatation in sealing zones. The proximal zone was affected in 45% and the distal in 52%. Patients with preserved seal had sealing zones twice as long as recommended. Post-EVAR rupture occurred in 13 patients, all with prior loss of seal. In study 4, the variables associated with loss of seal were diameter and length of the sealing zones measured at the CT one month after EVAR (p<0.001). Wider sealing zones required longer seal. The models could classify 1/3 of the patients as low risk for loss of seal with a negative predictive value of 88%. Conclusions: Post-EVAR rupture incidence has not declined during the last decades and mortality is high. The mechanism of rupture is a loss of seal in the stent graft sealing zones, most commonly due to vessel dilatation, resulting in an endoleak. Loss of seal is common and detectable using a structured protocol in CT review. Assessment of sealing zones may increase detection of loss of seal needing treatment and improve follow-up stratification. These measures could reduce post-EVAR ruptures.