Abdominal aneurysm sac thrombus CT density and volume after EVAR: which association with underlying endoleak?

BACKGROUND: Our aim was to analyse abdominal aneurysm sac thrombus density and volume on computed tomography (CT) after endovascular aneurysm repair (EVAR). METHODS: Patients who underwent EVAR between January 2005 and December 2010 and had at least four follow-up CT exams available over the first five years of follow-up were included in this retrospective single-centre study. Thrombus density and aneurysm sac volume were calculated on unenhanced CT scans. Linear mixed models were used for data analysis. RESULTS: Out of 82 patients, 44 (54%) had an endoleak on post-EVAR contrast-enhanced CT. Thrombus density significantly increased over time in both the endoleak and non-endoleak groups, with a slope of 0.159 UH/month (95% confidence interval [CI] 0.115-0.202), p < 0.0001) and 0.052 UH/month (95% CI 0.002-0.102, p = 0.041). In patients without endoleak, a significant decrease in aneurysm sac volume was identified over time (slope -0.891 cc/month, 95% CI -1.200 to -0.581); p < 0.001) compared to patients with endoleak (slope 0.284 cc/month, 95% CI -0.031 to 0.523, p = 0.082). The association between thrombus density and aneurysm sac volume was positive in the endoleak group (slope 1.543 UH/cc, 95% CI 0.948-2.138, p < 0.001) and negative in the non-endoleak group (slope -1.450 UH/cc, 95% CI -2.326 to -0.574, p = 0.001). CONCLUSION: We observed a progressive increase in thrombus density of the aneurysm sac after EVAR in patients with and without endoleak, more pronounced in patients with endoleak. The association between aneurysm volume and thrombus density was positive in patients with and negative in those without endoleak. RELEVANCE STATEMENT: A progressive increase in thrombus density and volume of abdominal aortic aneurysm sac on unenhanced CT might suggest underlying endoleak lately after EVAR. KEY POINTS: Thrombus density of the aneurysm sac after EVAR increased over time. Progressive increase in thrombus density was significantly associated to the underlying endoleak. The association between aneurysm volume and thrombus density was positive in patients with and negative in those without endoleak.

Impact of Post-EVAR Graft Limb Kinking in EVAR Limb Occlusion: Aetiology, Early Diagnosis, and Management.

OBJECTIVE/BACKGROUND: Endograft limb occlusion is a potential complication of endovascular aneurysm repair (EVAR), being one of the major causes of secondary interventions and rehospitalisation. The aim of this review is to report on the impact of endograft kinking in endograft limb occlusion, as well as on risk factors, prevention, early diagnosis, and management. METHODS: A systematic review and meta-analysis was conducted according to the recommendations of the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) statement. RESULTS: After a MEDLINE and Scopus search, 55 articles (27,509 patients) were included in the qualitative analysis and eight in the quantitative analysis. In this meta-analysis, 179 at risk limbs were treated by pre-emptive stenting, which significantly reduced the risk of limb occlusion: not pre-emptively stenting limbs at risk had a negative impact on graft limb patency (odds ratio 4.30, 95% confidence interval 1.45-12.78). Post-operatively, a kink was identified in 422 patients (1.5%), contributing to 42.8% of all limb occlusions. Relevant data support that completion angiography is an inadequate means of diagnosing high risk limbs, proposing cone beam computed tomography and intravascular ultrasound as adjuncts. The post-operative limb occlusion rate ranged from 0% to 10.6%, affecting 984 patients. Several risk factors for limb occlusion have been identified. Regarding treatment, most patients were submitted to femorofemoral bypass (52.3%) or to deployment of a bare metal stent, either alone or associated with catheter directed thrombolysis or mechanical thrombectomy (26.4%). Complications and outcome after re-intervention for limb occlusion are described infrequently in the literature, but single studies have reported on re-occlusion, major amputation, and limb occlusion related mortality rates. CONCLUSION: Pre-EVAR planning should focus on identification of risk factors for kinking. Adjunctive stenting is an effective prophylaxis for selected high risk limbs, yet intra-operative identification remains problematic. Also, it is noteworthy that most limb occlusions occur in the first year after EVAR, emphasising the importance of careful early follow up of high risk patients.