The role of ascending aortic size in outcomes of patients with uncomplicated acute type B aortic dissection

Objective

Recent studies demonstrate that uncomplicated acute type B aortic dissection (uATBAD) patients with enlarged descending thoracic aortic diameters are at high risk for development of complications. This study aimed to determine the association of maximum ascending aortic diameter and area and outcomes in patients with uATBAD.

Methods

All patients admitted with uATBAD from June 2000 to January 2015 were reviewed, and those with available imaging were included. All measurements were obtained by a specialized cardiovascular radiologist, including the maximum ascending aortic diameter and area. Outcomes, including the need for intervention and mortality, were tracked over time. Data were analyzed by stratified Kaplan-Meier and multiple Cox regression analyses using SAS 9.4 software (SAS Institute, Cary, NC).

Results

During the study period, 298 patients with uATBAD were admitted, with 238 having available computed tomography and 131 having computed tomography angiography imaging and adequate follow-up available for analysis. The cohort had an average age of 60.96 ± 13.4 years (60% male, 53% white). Ascending aortic area >12.1 cm² and ascending aortic diameter >40.8 mm were associated with subsequent arch and proximal progression necessitating open ascending aortic repair (P < .027 and P < .033, respectively). Ascending diameter >40.8 mm predicted lower intervention-free survival (P = .01). However, it failed to predict overall survival (P = .12). Ascending aortic area >12.1 cm² predicted lower intervention-free survival (P = .005). However, this was not predictive of mortality (P = .08). Maximum aortic diameter along the length of the aorta >44 mm persisted as a risk factor for mortality (P < .001). Neither maximum ascending aortic diameter >40.8 mm (hazard ratio HR], 1.09; 95% confidence interval CI], 0.42-2.83; P = .85) nor area >12.1 cm² (HR, 0.992; 95% CI, 0.38-2.61; P = .99) significantly predicted mortality when controlling for maximum aortic diameter along the length of the aorta >44 mm (HR, 7.34; 95% CI, 2.3-23.41; P < .001), diabetes mellitus (HR, 6.4; 95% CI, 2.17-18.93; P < .001), age (HR, 1.06/y; 95% CI, 1.03-1.10; P < .001), history of stroke (HR, 5.03; 95% CI, 1.52-16.63; P = .008), and syncope on admission (HR, 21.11; 95% CI, 2.3-193.84; P = .007). Ascending aortic diameter >40.8 mm (HR, 2.01; 95% CI, 1.03-3.95; P = .04) and maximum ascending aortic area >12.1 cm² (HR, 1.988; 95% CI, 1.02-3.87; P = .04) on admission persisted as predictors of decreased intervention-free survival after controlling for maximum aortic diameter along the length of the aorta >44 mm (HR, 3.142; 95% CI, 1.47-6.83; P < .004), syncope on admission (HR, 26.3; 95% CI, 2.81-246; P < .004), and pleural effusion on admission (HR, 3.02; 95% CI, 1.58-5.77; P < .001).

Conclusions

uATBAD patients with ascending aortic area >12.1 cm² or maximum ascending aortic diameter >40.8 mm are at high risk for development of subsequent arch and proximal progression and may require closer follow-up or earlier intervention. Ascending aortic size (diameter and area) is predictive of decreased intervention-free survival in patients with uATBAD.