Impact of False Lumen Occluders on Aortic Remodeling after Endovascular Repair of Chronic Type B Dissection

OBJECTIVE To evaluate morphological and clinical outcomes after False Lumen Occluder (FLO) implantation for post-dissection thoracoabdominal aortic aneurysm (PD-TAAA) and to investigate the impact of adjunctive false lumen embolization on aortic remodeling. METHODS A retrospective single-center study included 71 patients (median age 64 years, IQR 58-70; 77.5% male) with chronic type B aortic dissection (cTBAD) treated between June 2018 and December 2024 with third-generation FLO implantation during thoracic endovascular aortic repair (TEVAR) or fenestrated/branched repair (F/BEVAR). Aortic, true lumen (TL), and false lumen (FL) volumes were quantified using three-dimensional reconstructions on Aquarius software. FLO remodeling was defined as compression of the occluder with a crescent shape on follow-up imaging.Aortic remodeling (false lumen regression) was defined as a ≥10% reduction in FL volume, stability as ±10% change, and enlargement as >10% increase compared with baseline. Associations between clinical, anatomical, and procedural variables and remodeling outcomes were analyzed using non-parametric and mixed-effects models. RESULTS Across 268 imaging examinations, total aortic and FL volumes decreased significantly over time, while TL volume expanded (all p<0.001). Median total aortic volume declined from 796 cm3 at 1 month to 706 cm3 at 4 years, and FL volume decreased from 501 cm3 to 296 cm3, while TL volume increased from 287.5 cm3 to 358 cm3. Median follow-up was 13.3 (5.6-36.5) months.Aortic remodeling occurred in 83.1% of patients, FL stability in 12.7%, and enlargement in 4.2%. Regression was more frequent in younger patients (p=0.048) and those with smaller baseline diameters and volumes (p=0.043 and p=0.034).Adjunctive embolization was strongly associated with TL expansion (χ2=5.8, p=0.016) and FLO remodeling (χ2=5.2, p=0.022), and showed a trend toward increased aortic remodeling (χ2=4.8, p=0.056) without added mortality or morbidity. No cases of spinal cord ischemia occurred. FLO size (≥40 vs <40 mm) and position (thoracic, diaphragmatic, or abdominal) did not influence outcomes. FLO remodeling was strongly correlated with concurrent FL reduction (χ2=20.8, p<0.001) and may represent a radiologic marker of procedural success. CONCLUSIONS FLO implantation provided durable aortic remodeling in cTBAD, while adjunctive embolization enhanced remodeling efficacy by eliminating residual perfusion without increasing risk. The absence of spinal cord ischemia and the identification of FLO remodeling as a surrogate of success highlight the value of this combined, low-risk strategy for long-term aortic stability.