Prognostic value of initial hematoma area in patients with acute type B aortic intramural hematoma

Aortic intramural hematoma (IMH) is a subtype of acute aortic syndrome (AAS), and acute type B IMH, which mainly involves the descending thoracic aorta, is the most common form. Although conventional imaging markers have been used to predict outcomes, they mainly reflect focal or linear features. Area-related parameters on initial computed tomography angiography (CTA) images may provide a more accurate assessment of cross-sectional hematoma burden than traditional linear measurements. This study aimed to evaluate whether adding area-related CTA parameters improves prediction of 1-year aortic-related adverse events in patients with acute type B IMH.

This study retrospectively reviewed admission and follow-up data from 290 patients with acute uncomplicated type B IMH. Patients were categorized into stable (N=180) and exacerbation (N=110) groups based on the occurrence of aortic-related adverse events within one year. By using least absolute shrinkage and selection operator (LASSO) regression combined with multivariate logistic regression, independent predictors were identified. A base model excluding area parameters and an enhanced model incorporating parameters such as hematoma area were constructed. The incremental prognostic value of hematoma area-related parameters was assessed using the net reclassification improvement (NRI), decision curve analysis (DCA), and internal validation with 1,000 bootstrap resamples.

Aortic arch involvement, abdominal aortic involvement, maximal descending aortic area (MDAA) >980 mm², hematoma area ratio >37.5%, presence of ulcer-like projections (ULPs), and higher white blood cell (WBC) count were identified as independent predictors of progression. The enhanced model, which incorporated the area-based parameters (MDAA >980 mm² and hematoma area ratio >37.5%), had better performance compared with the base model, with better discrimination [area under the curve (AUC) 0.745 vs. 0.664], improved reclassification (NRI 0.543), higher concordance index (C-index) (0.724 vs. 0.647), improved calibration (calibration slope 0.891 vs. 0.883; lower Emax 0.032 vs. 0.036), greater explanatory power (Nagelkerke R2 0.189 vs. 0.072), and higher clinical net benefit.

Area-related imaging parameters have incremental prognostic value in patients with acute uncomplicated type B IMH and may help better identify high-risk patients and support more timely clinical decision-making in the future.