['To investigate the predictors of failed false lumen (FL) volume reduction at 12 months after stent-graft implantation in patients with type B aortic dissection.', 'The retrospective analysis comprised 38 patients (25 men; mean age 60±12 years) with double-barrel type B aortic dissection (9 acute) treated with thoracic endovascular aortic repair (TEVAR) and evaluated with serial computed tomography (CT) scans up to 12 months. Aortic volume changes were determined. Based on FL volume change at 1 year after stent-graft implantation, patients were dichotomized according to the presence or absence of FL volume reduction. Clinical and CT variables were compared between groups to determine risk factors of failed FL volume reduction. A major adverse event (MAE) was defined as death or reintervention.', 'Patients were followed for 4.2±2.8 years. FL volume reduction (+FLVR) occurred in 27 (71%) patients, whereas 11 (29%) patients had no FL volume reduction (-FLVR). The MAE-free survival rate was significantly higher in the +FLVR patients than in the -FLVR group (88.9% vs. 27.3%, respectively; p=0.001). Chronicity of dissection, location of tear site, or the maximum total aortic lumen area was not associated with failure to achieve FL volume reduction. However, the maximum preprocedure FL area was significantly lower in the +FLVR group than in the -FLVR group (12.6±6.6 vs. 21.0±11.4 cm(2), respectively; p=0.041) and was an independent predictor for failed FL volume reduction (odds ratio 1.3, 95% confidence interval 1.02 to 1.70, p=0.031).'] Is large false lumen area a predictor of failed false lumen volume reduction after stent-graft repair in type B aortic dissection?