Outcomes Of Primary Determinate And Indeterminate Target Vessel Endoleaks After Fenestrated-Branched Endovascular Aortic Repair

Objective: To investigate the outcomes of primary target vessel endoleaks after fenestrated-branched endovascular aortic repair (F/B-EVAR) for pararenal/juxtarenal or thoracoabdominal aortic aneurysms. Methods: This was a single-center, retrospective study (2010-2023) on F/B-EVAR for thoracoabdominal (TAAA), pararenal (PRAA), or juxtarenal (JRAA) aortic aneurysms. Computed tomography angiography (CTA) was obtained within 30 days, at 3, 6, 12 months, and yearly thereafter. Target vessel endoleaks were classified as “primary” if present at the first post-operative CTA. Endoleaks were defined “determinate” (dEL) if the cause (Type Ic or IIIc) and the implicated target vessel were identifiable; endoleaks were defined “indeterminate” (iEL) if contrast enhancement was detectable at the level of fenestrations or branches without any evident source, as assessed by two independent physicians. Endoleaks involving multiple inflows (Type II and target vessel-related) were defined “complex” (cEL). Endpoints of this study were endoleak persistence >6 months, 1-year aneurysm sac failure to regress (>5 mm diameter decrease), and 4-years endoleak-related secondary interventions (e.g. embolization, relining). Kaplan-Meier estimates and Cox proportional regression models were used for the analysis. Results: This study included 112 patients (n=60 [54%] PRAA/JRAA, n=51 [46%] TAAA), with 394 target vessels incorporated through fenestrations (n=214 [54%]), or directional branches (n=180 [46%]). One patient had a type B aortic dissection. Twenty-five patients (22%) had a primary target vessel-related endoleak, of which 16 (64%) determinate (10 Type IIIc, 1 Type Ic, and 5 complex endoleaks with Type II and target vessel components) and 9 (36%) indeterminate. Spontaneous resolution occurred in 73% dEL, and 79% iEL (OR 0.07; 95%CI 0.02-0.23; P<.001) during follow-up. Persistence for more than 6 months was more likely for cEL (OR 50; 95%CI 10-494; P<.001), and branch-related iEL (OR 40.4; 95%CI 3.4-5683, P=.002) rather than fenestration-related iEL (OR 4.81; 95%CI 0.90-25.9; P=.065). After 1 year of follow-up, aneurysm failed to regress in 88% patients with determinate endoleak, 100% patients with indeterminate endoleak and 84% patients without a primary endoleak (OR 3.58; 95%CI 0.42-470; P=.300). Persistent endoleaks (OR 2.22; 95%CI 1.18-5.79; P=.017), complex endoleaks (OR 2.16; 95%CI 1.12-4.34; P=.033), and branch-related indeterminate endoleaks (OR 5.10; 95%CI 1.27-9.28; P=.001) were associated with aneurysm failure to regress. Freedom from re-intervention for target vessel instability at 4 years of follow-up was 57.9% (dEL: 50%, 95%CI 42-54; iEL: 89%, 95%CI 79-100) in patients with primary target vessel endoleak, 91.1% (95%CI 87-94) in patients without primary target vessel endoleak. Endoleaks persisting over 6 months were associated with re-intervention (HR 3.13, 95%CI 1.04-8.89; P=.045). In case of re-intervention, iELs and cELs were at higher risk for multiple secondary procedures (HR 2.67, 95%CI 1.2-10.3; P=.041). Conclusions: Primary target vessel dEL and iEL are frequent after F/B-EVAR. dEL and post-FEVAR iEL spontaneously resolve in majority of cases. Differently, post-BEVAR iEL and cEL are more likely to persist, and be associated with aneurysmal sac failure to regress. Persistent endoleaks may require re-interventions, and multiple secondary procedures may be necessary in case of iEL or cEL. In these cases, a dynamic imaging follow-up may be considered for better assessment.