(PC022) Effect of Interfenestration Distance in Target Vessel Instability in Patients undergoing FBEVAR

Objectives: Target artery (TA) issues are the most common cause of secondary intervention following fenestrated endovascular aortic repair (FBEVAR). Several factors associated with TA instability (TAI) have been identified. The aim of this study is to assess the impact of distance between adjacent fenestrations on TAI following FBEVAR.

Methods: A single center review of prospectively and retrospectively collected data of patients undergoing FBEVAR for aortic aneurysms involving ≥3 renal/mesenteric arteries incorporated via reinforced fenestration between 2007 and 2024 was undertaken. Inter-fenestration distance (IFD) was determined based on device design plans (Figure 1). Patients with superior mesenteric artery (SMA) or renal artery (RA) directional branches were excluded from the study. Celiac axis (CA) directional branches or scallops were excluded from analysis, but patients were still included for analysis of SMA and RA. Our primary outcome was TAI which included type 1C and 3C endoleak, bridging stent or TA stenosis, occlusion, kink or fracture.

Results: There were 861 patients treated with FBEVAR and 314 patients (74% male, mean age 76±7 years) met the inclusion criteria. Of these, 218 patients (69%) were treated with company manufactured patient-specific devices, whereas 96 (31%) underwent repair with PMEGs. A total of 1218 mesenteric and renal TAs were incorporated with reinforced fenestrations. Mean IFD distance between the CA and SMA was 21.0±6.2mm, SMA and right RA (RRA) was 22.7±9.1 mm, SMA and left RA (LRA) was 25.3±7.3mm, and between LRA and RRA was 34.4±8.4mm. Median follow-up was 3.1 years. Freedom from CA, SMA, RRA and LRA instability at five-years was 97%, 91%, 90% and 93%, respectively. Patients with SMA-LRA distance < 19.6 mm had a higher risk of LRA instability (hazard ratio 3.2, 95% confidence interval, 1.3-8.2) (Figure 2). Specifically, LRA instability occurred in 20 patients and causes included endoleak and stenosis in 10 patients each. There was a trend towards increased risk of RRA instability if the interrenal fenestration distance was < 28.1 mm (hazard ratio 2.1, 95% confidence interval, 0.87-5.3). Similarly, there was a trend toward a higher risk of SMA instability when the SMA-LRA IFD was < 22.9 mm (hazard ratio 2.2, confidence interval, 0.95-5.1).

Conclusions: A distance < 19.6 mm between superior mesenteric and left renal artery fenestrations was associated with increased incidence of left renal artery instability following FBEVAR independent of device type. While causality cannot be determined by these data, the association should be further explored as it could impact future device design and planning.