Prevalence and the Relevance of CT-Morphologic Predictors for Disease Progression in Uncomplicated Type B Aortic Dissection

Abstract

Introduction - To analyze the prevalence and significance of CT-morphologic predictors of aortic diameter expansion (ADE) in patients with uncomplicated acute Type B aortic dissection (TBAD). Methods - This retrospective analysis enrolled 65 patients (40 males, 25 females, mean age 58.3 ± 10.5 years) with TBAD under best medical treatment (BMT) between March 2003 and April 2016 at two tertiary centers. The initial (baseline) CT-scans and the one-year follow-up (median FU 11.6 months, IQR 8.4) scans were reviewed by two independent readers using a standardized measurement protocol and the centerline on a CE marked workstation. The following previously published independent predictors were analyzed: primary entry tear (PET) diameter ≥10 mm1, its location at the concavity of the aortic arch2, maximum descending aortic diameter ≥40 mm3, false lumen (FL) diameter ≥22 mm4, partial false lumen thrombosis5 and a fusiform index (FI) of ≥0.646. The endpoints were aortic expansion rate in mm at 1 year, prevalence of each and presence of multiple predictors. Results - An aortic diameter expansion (ADE) ≥5mm was observed in 37 out of 65 patients (57%) at 1 year. The extrapolated growth rate per 12 months averaged 8.2 ± 8.2 mm and the observed ADE was 6.2 ± 5.7 mm within the median FU. The regression analysis showed 2.5 ± 1.9 mm growth per predictor (CI -0.2-5.2 mm ± 0.7-3.0 mm; p=.003). ADE was accelerated by 1.9 mm per predictor within 1 year. The prevalence of predictors was: PET at the arch concavity in 11% (n=7), PET diameter ≥10 mm in 55% (n=36), maximal descending aortic diameter ≥40 mm in 38% (n=25), false lumen diameter ≥22 mm in 29% (n=19), partial false lumen thrombosis in 48% (n=31) and FI ≥ 0.64 in 18% (n=12). No predictors were found in 11% (n=7) of patients, one in 22% (n=14), two in 35% (n=23), three in 23% (n=15), four in 9% (n=6). A mean of 1.98 ± 1.1 predictors per patient were registered, 67% of patients presented at least 2 predictors each. Conclusion - A significant ADE is observed in every second uncomplicated TBAD patient under BMT within the first year following diagnosis. A correlation between the number of predictors and the annual growth rate was found. Therefore, CT-based predictors may help to define TBAD-patients at risk for expansion, and who may benefit from early endovascular repair. Further studies with larger cohorts and a longer FU are warranted.