Phd in ANGIO-CARDIO-THORACIC PATHOPHYSIOLOGY AND IMAGING

Thesis title: The Impact of Bridging Stent Configuration on Renal Function Following Branched and Fenestrated Endovascular Aortic Repair

Introduction Open thoracoabdominal aortic aneurysm (TAAA) repair carries significant risks. Fenestrated/branched endovascular aortic repair (F/BEVAR) offers a less invasive alternative, but reno-visceral complications persist. Renal artery compromise is common, impacting outcomes. Fenestration vs. branch bridging is debated; fenestrations show improved patency, but data is limited. Serum creatinine is an insensitive GFR marker. This study investigates early renal function decline post-F/BEVAR (branch vs. fenestration) using 99mTc-DTPA scintigraphy. Methods 112 F/BEVAR patients (San Camillo Hospital, 2018-2021) were prospectively stratified by renal bridging strategy: fenestration or branch. All underwent pre/post-operative (2 weeks/3 months) 99mTc-DMSA scintigraphy (total/split GFR, time-to-peak), and annual creatinine. CMDs/T-branch use was recorded. Algorithm prioritized branches for downward arteries, fenestrations for upward. Detailed anatomic assessment was done by preoperative CTA. Follow-up included annual/biannual CTA, CEUS, and creatinine. SPSS was used for Chi-square, T-tests, ANOVA, and regression (p<0.05). Primary outcomes were 30-day MAE, technical success, and GFR changes. Secondary outcomes included predictive indicators of GFR decline and scintigraphy/eGFR correlation at two years. Results The branch group (n=63, 126 renal arteries) and fenestration group (n=49, 100 renal arteries) had similar baseline GFR (58.4±18.6 vs. 65.1±19.8 ml/min, p=0.873). All fenestration patients had CMDs, while branch patients had mostly T-branches (n=58) and some CMDs (n=5). Contrast volume was lower with fenestrations (123±17 vs. 142±58 ml, p=0.089). Aortic coverage was greater in branches (341.7±95.9 vs. 255.2±88.5 mm, p=0.042). Bridging stent length differed significantly (35.2±2.4 vs. 59.1±22.5 mm, p=0.052). One fenestration patient had access/AKI requiring intervention. No 30-day mortality occurred. 3-month target vessel patency was 99.2%. Branch configuration was the only predictor of split GFR decline (p=0.001), with scintigraphy demonstrating significantly greater GFR decline in branches (-3.5±0.6 vs -15.4±5.4 ml/min, p=0.001) and prolonged peak time (p=0.033). Two-year survival was 100%, with 99.2% patency. Conclusions Dynamic renal scintigraphy revealed significantly greater and sustained GFR decline in F/BEVAR patients with branch-based renal revascularization versus fenestrations, alongside prolonged radiotracer uptake time. Fenestration-based strategies may offer superior renal protection. Further long-term monitoring is needed to define clinical implications.