New type A dissection after acute type B aortic dissection.

OBJECTIVE: Aortic dissection is a dynamic process that can progress both proximal and distal to the initial entry tear. We sought to determine associations for development of proximal progression or new type A aortic dissection (NTAD) after acute type B dissection (ATBD) and its effect on survival of the patient. METHODS: We reviewed all cases of acute aortic dissection that we managed from 1999 to 2014. Univariate and bivariate analyses were performed to identify correlates of NTAD. Multivariable regression and proportional hazards regression analysis was done to determine the effect of dissection progression on long-term survival. RESULTS: Among 477 cases of ATBD managed, 19 (4.0%) patients developed NTAD during a median follow-up of 4.1 (interquartile range, 1.4-7.7) years. Median time from diagnosis of ATBD to NTAD was 124 (interquartile range, 23-1201) days. Baseline predictors for development of NTAD at initial ATBD admission included bicuspid aortic valve (P = .006) and age <60 years (P = .012). Although not statistically significant, point estimates indicate that thoracic endovascular aortic repair was twice as frequent in NTAD cases as in non-NTAD cases. Overall 5-year survival was 70.2%. Patients who had repair of NTAD appear to have longer survival, although this effect is on the margin of statistical significance (P = .051). After risk factor and correlates of NTAD adjustment, this effect was no longer apparent (P = .089). CONCLUSIONS: The natural history of ATBD is such that there is a persistent risk of NTAD, with the highest risk in the first 6 months. Factors associated with NTAD include bicuspid aortic valve and young age. Thoracic endovascular aortic repair did not have a large effect on risk. Timely diagnosis and repair of NTAD are associated with good survival rates. Lifelong surveillance is warranted in all cases of descending thoracic aortic dissection regardless of initial treatment modality.