Aneurysm sac regression after fenestrated and branched endovascular repair for thoracoabdominal aortic aneurysms is associated with improved long-term survival.

OBJECTIVE: This study evaluated the association between sac regression at one year and long-term outcomes after fenestrated and branched endovascular aortic repair (f/bEVAR) for thoracoabdominal aortic aneurysm (TAAA). METHODS: A retrospective single-center cohort study was conducted of patients who underwent f/bEVAR for TAAA between April 2006 and March 2025 and had computed tomography angiography at one year. Sac diameter change was categorized as regression (≥5 mm decrease), stable (+/- 5 mm change), or growth (≥5 mm increase). Stable and growth were combined as failure to regress. The primary outcome was all-cause mortality. Secondary outcomes included late type I/III endoleaks and late reintervention. Kaplan-Meier analysis and Cox models were used. RESULTS: Sixty-eight patients met inclusion criteria. Sac regression one year after f/bEVAR occurred in 24 patients (35.3%), whereas 44 (64.7%) demonstrated failure to regress (35 stable, 51.5%; nine growths, 13.2%). Median age was 67.5 years (IQR 65.0 - 74.8) and 74.0 years (IQR 68.0 - 76.8), and 12 (50.0%) and 32 (72.7%) patients were male, for the aneurysm regression and failure to regress groups, respectively. During a median follow-up of 56.5 months, overall mortality was 55.9% (38 patients). In a univariable model, failure to regress was significantly associated with higher all-cause mortality (HR 2.78, 95% CI 1.33-5.81; p=.007). This association was confirmed in multivariable analysis (HR 2.55, 95% CI 1.14-5.71; p=.023). Although there was no association between failure to regress and late type I or III endoleak (HR 1.50, 95% CI 0.48-4.64: p=.48), the need for late reintervention was higher for patients with failure to regress (HR 3.03, 95% CI 1.09-8.37; p=.033). Notably, all late reinterventions were percutaneous (5 main body relinings/extensions; 14 bridging-stent related; 2 coiling procedures) and did not increase mortality risk (HR 0.95, 95% CI 0.48-1.90; p=.89). CONCLUSIONS: Aneurysm sac failure to regress at one year after f/bEVAR for TAAA is associated with worse long-term survival and increased reintervention rate. The predictive value of aneurysm sac dynamics at 1 year CTA, for adverse outcomes highlights its potential for risk stratification and guiding patient specific treatment regimen.