Outcomes of Combined Inner Branch and Fenestration Endograft for Endovascular Repair of Complex Abdominal and Thoracoabdominal Aneurysms: An International Multicentre Study

Background: Custom-made endografts combining fenestrations (FENs) and inner branches (IBs) within the same device represent an evolving strategy for the endovascular treatment of complex aortic aneurysms and thoracoabdominal aneurysms. However, the factors driving the choice between these incorporation techniques and their impact on target vessel outcomes remain poorly understood. This study therefore aimed to assess peri-operative and mid-term outcomes of combined FEN+IB endograft repair, compare target vessel instability (TVI) between fenestrated and inner branch configurations according to target-vessel type, and identify anatomical and institutional factors associated with the selection of each incorporation technique. Methods: This study was a retrospective, observational, cohort study based on data obtained from a multicentric international collaboration. Consecutive patients treated for juxtarenal, pararenal or thoracoabdominal aortic aneurysms, or other aortic pathologies involving the renovisceral segment, by Cook custom-made device combining IB + FEN endografts were included. Endpoints followed SVS reporting standards. Pre-operative clinical and anatomical characteristics, procedural data, thirty-day postoperative outcomes and available follow-up data were collected. Freedom from TVI was assessed using Kaplan–Meier analysis. Associations between anatomical factors and target-vessel incorporation strategy were evaluated by Mann–Whitney U or χ²/Fisher's exact test. Results: A total of 102 patients (mean age 74.4 years; 78.4% male) and 398 target vessels were treated (48.2% IB, 51.5% Fen). Degenerative aneurysm was the primary indication for treatment (88%), followed by chronic dissection (3.9%), pseudoaneurysm (2.0%), and type IA endoleak (2.0%). The most frequent device configurations were 2 IBs + 2 FENs (57.8%) and 1 IB + 3 FENs (19.6%). Visceral vessels were more frequently incorporated using FENs (celiac trunk 58.8%, superior mesenteric artery 68.6%), whereas renal arteries were more commonly incorporated using inner branches (right renal artery 55.9%, left renal artery 65.7%). Local aortic diameter > 30 mm and aortic extent were significantly associated with IB use at the celiac trunk (p = 0.016) and pooled renal arteries (both p < 0.001). Centre-specific variability was marked (p <0.001). Technical success was achieved in 99.7% of cases. Thirty-day mortality was 2.9%, while major adverse events and spinal cord ischemia occurred in 15.7% and 6.9% of patients, respectively. At one year, freedom from TVI was higher for visceral than renal vessels (97.6% vs 93.5%; p=0.124), although no significant differences were observed between incorporation techniques. Conclusion: Combined FEN+IB endografts provide high technical success rates and excellent mid-term freedom from target vessel instability. FEN and IB configurations demonstrated comparable target vessel outcomes, without a detectable TVI difference between incorporation strategies. The choice of incorporation technique appears to be influenced not only by anatomical characteristics, such as local aortic diameter and disease extent, but also by institutional preferences, suggesting that different strategies may achieve equivalent results when appropriately tailored to the patient's anatomy.