Impact of Initial Aortic Diameter on Mortality in Acute Type B Aortic Dissection

Among the high-risk features used to describe type B aortic dissection (TBAD), initial diameter has been linked to aortic events more consistently. The aim of the study was to review the impact of initial aortic diameter of >40 mm on index (in-hospital) and long-term mortality. This is a single-center retrospective analysis of all consecutive patients with acute TBAD over 22 years (2000-2022). Comparative analyses of preoperative characteristics were conducted for two groups: those with an initial aortic diameter of >40 mm (Group 1) and those without (Group 2). The primary endpoint was mortality at index admission. Secondary endpoints were mortality at 5 and 10 years. Other secondary endpoints were length of stay and operative complications. Multivariate logistic regression was used to predict 30-day mortality. Kaplan-Meier analysis was used for survival estimates. χ2 and Wilcoxon rank sum tests were used to compare categorical and continuous variables between the two groups, respectively. Median follow-up was 7.0 years (interquartile range [IQR], 3.0-14.0 years). There were 309 eligible patients (117 female [37.9%]; mean age, 61.5 ± 14.3 years) treated for acute TBAD, including 214 (69%) in Group 1 and 90 (31%) in Group 2. Both groups had similar demographics. Group 1 had higher rates of complicated dissections (60.8% vs 48.4%; P = .043) and a need for operative repair (49.1% vs 33.7%; P = .012). The rate of endovascular repair was similar between groups. Postoperative complication rates were similar except higher rate of altered mental status in Group 1 (21.0% vs 8.4%; P = .007). Median length of stay was longer in Group 1 (12.5 days vs 9.0 days; P < .001). A multivariate model controlling for complicated TBAD and aortic repair demonstrated higher odds of index admission mortality in Group 1 (8.9% vs 1.1%; P = .010; odds ratio [OR], 8.37; 95% confidence interval [CI], 1.06-65.78) (Table). The 5-year and 10-year survival estimates were lower in Group 1 (71.2% and 67.3% vs 83.1% and 78.3%; P = .021) (Fig). In patients with of acute TBAD, those presenting with aortic diameter >40 mm are more likely to die during the index admission, especially if they were complicated. Those patients require a higher level of care and closer than usual follow-up. Initial aortic diameter should be an independent risk of mortality regardless of symptoms.TableIndex admission mortality rates compared across Group 1 (aorta >40 mm) vs Group 2 (aorta ≤40 mm)Index admission mortalityGroup 1Group 2P-valueTotal8.9%1.1%.010Complicated acute TBAD11.5%0.0%–Uncomplicated acute TBAD4.8%2.1%.633TBAD, Type B aortic dissection. Open table in a new tab