It is not well known if the size of the ascending thoracic aorta at presentation predicts features of presentation, management, and outcomes in patients with acute type B aortic dissection. The International Registry of Acute Aortic Dissection (IRAD) database was queried for all patients with acute type B dissection who had documentation of ascending thoracic aortic size at time of presentation. Patients were categorized according to ascending thoracic aortic diameters ≤4.0, 4.1 to 4.5, and ≥4.6 cm. Four hundred eighteen patients met inclusion criteria; 291 patients (69.6%) were men with a mean age of 63.2 ± 13.5 years. Ascending thoracic aortic diameter ≤4.0 cm was noted in 250 patients (59.8%), 4.1 to 4.5 cm in 105 patients (25.1%), and ≥4.6 cm in 63 patients (15.1%). Patients with an ascending thoracic aortic diameter ≥4.6 cm were more likely to be men (p = 0.01) and have Marfan syndrome (p <0.001) and known bicuspid aortic valve disease (p = 0.003). In patients with an ascending thoracic aorta ≥4.1 cm, there was an increased incidence of surgical intervention (p = 0.013). In those with an ascending thoracic aorta ≥4.6 cm, the root, ascending aorta, arch, and aortic valve were more often involved in surgical repair. Patients with an ascending thoracic aorta ≤4.0 were more likely to have endovascular therapy than those with larger ascending thoracic aortas (p = 0.009). There was no difference in overall mortality or cause of death. In conclusion, ascending thoracic aortic enlargement in patients with acute type B aortic dissection is common. Although its presence does not appear to predict an increased risk of mortality, it is associated with more frequent open surgical intervention that often involves replacement of the proximal aorta. Those with smaller proximal aortas are more likely to receive endovascular therapy.
Patients with type B dissections often have important co-morbid aortic, valvular, or other cardiovascular conditions complicating their management. Using ascending aortic dimensions as a surrogate marker for extent of aortic disease, we sought to determine if there were any differences in management and outcomes in type B dissection cases from the International Registry of Acute Aortic Dissection (IRAD) based on ascending aortic size measurements.
Methods
The IRAD is an ongoing multicenter international registry that was initiated in 1996. The structure and content of the registry data have been outlined in previous publications. All cases of acute dissection at participating hospitals are identified at presentation or retrospectively based on hospital discharge diagnoses. Cases included in the registry are nontraumatic Stanford type A and B dissections in patients who present within 14 days of symptom onset.
Patients included in this analysis were enrolled in the IRAD from January 1, 1996 to May 2008. All patients with acute type B dissection, defined by presence of a dissection that does not involve the ascending aorta with an entry tear that is distal to the left subclavian artery, were included in the initial search. Of all type B dissection cases identified, only those with ascending aortic dimensions recorded in the registry were included in the final analysis. Ascending aortic sites include the aortic annulus, root (sinus of Valsalva), sinotubular junction, and ascending aorta. Size documented was taken from ≥1 imaging method including transthoracic or transesophageal echocardiography, computed tomography, magnetic resonance imaging, or invasive aortography. Maximum ascending aortic dimension was the largest aortic dimension reported on any of these imaging methods at time of presentation.
Patients were categorized into 3 groups based on the largest reported ascending aortic diameter. Group 1 included those who had a maximal ascending aortic size ≤4.0 cm. Group 2 included patients with a maximal ascending aortic size of 4.1 to 4.5 cm. Patients in group 3 had ascending aortic dimensions ≥4.6 cm. Differences in demographic, presentation, management, and outcome variables were assessed among groups.
Categorical data are presented as frequencies and percentages and continuous data are represented by means ± SDs. Three-way chi-square analysis (or Fisher’s exact test, when appropriate) was performed to define differences among the 3 groups for categorical variables. Where appropriate, Bonferroni adjustments and statistical tests for ordinal trends were performed. In all cases, missing data were not defaulted to negative, and denominators reflect only cases reported. A p value <0.05 was considered statistically significant unless otherwise stated. SPSS 15.0 (SPSS, Inc., Chicago, Illinois) was used for analysis.
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