Predictors of intervention and mortality in patients with uncomplicated acute type B aortic dissection.

OBJECTIVE: Patients with uncomplicated acute type B aortic dissection (uATBAD) have historically been managed with medical therapy. Recent studies suggest that high-risk patients with uATBAD may benefit from thoracic endovascular aortic repair. This study aims to determine the predictors of intervention and mortality in patients with uATBAD.
METHODS: All patients admitted with uATBAD from 2000 to 2014 were reviewed, and those with computed tomographic angiography imaging were included. Multiplanar reconstruction was used to obtain double orthogonal oblique measurements. All measurements were obtained by a specialized cardiovascular radiologist (D.O.). The maximum aortic diameter, proximal descending thoracic aorta false lumen (FL) diameter, and area were recorded. Outcomes, including the need for intervention and mortality, were tracked over time. Data were analyzed by stratified Kaplan-Meier and multiple Cox regression analysis using SAS v 9.4 (SAS Institute, Cary, NC).
RESULTS: During the study period, 294 patients with uATBAD were admitted with 156 having admission computed tomographic angiography imaging available for analysis. The cohort had an average age of 60.6 years (±13.6 years); 60% were males. The average follow-up time was 3.7 years (interquartile range, 2.1-6.9). A stratified analysis demonstrated the most sensitive cutoff for mortality was aortic diameter >44 mm (P < .01), and it appeared to be a threshold effect with minimal additional information added by finer size stratification. FL diameter did not predict mortality in our series (P = .36). Intervention-free survival, alternatively, appeared to decrease over the range of diameters from 35 to 44 mm (P < .01). An FL diameter >22 mm was associated with decreased intervention-free survival (P < .04). Age >60 years on admission also demonstrated decreased survival compared with those ≤60 years of age (P < .01). Diameter >44 mm persisted as a risk factor for mortality (hazard ratio, 8.6; P < .01) after adjustment for diabetes (6.7; P < .01), age (1.06/y; P < .01), history of stroke (5.4; P < .01), connective tissue disorder (2.3; P < .01), and syncope on admission (9.5; P < .04). The 1-, 5-, and 10-year intervention rate for patients with admission aortic diameter >44 mm was 18.8%, 29.5%, and 50.3%, respectively, compared with 4.8%, 13.3%, and 13.3% in the ≤44 mm group (P < .01).
CONCLUSIONS: Aortic diameter >44 mm is a predictor of mortality after adjustment for other significant risk factors. Age >60 years on admission is a predictor of mortality. An FL diameter >22 mm as well as those with maximum aortic diameter >44 mm on admission were associated with decreased intervention-free survival. Patients with these high-risk criteria may benefit from thoracic endovascular aortic repair. Further studies are needed to further define those patients at highest risk and, thus, most likely to benefit from early intervention.