FT11. The Optimal Aortic Diameter for Risk of Late Aortic Events in Uncomplicated Stanford Type B Aortic Dissection

Abstract

The initial treatment of uncomplicated acute type B aortic dissection (ATBAD) has previously been mainly medication. Almost half of patients require aortic surgery in the chronic phase. The initial aortic diameter is a risk factor for late aortic events in patients with uncomplicated ATBAD. However, the cutoff value remains controversial, 40 mm or 45 mm. We evaluated the optimal aortic diameter for risk of late aortic events in patients with uncomplicated ATBAD. We conducted a retrospective cohort study reviewing 175 consecutive patients who underwent initial treatment for uncomplicated ATBAD between October 2004 and May 2017. We excluded 47 patients with complicated ATBAD (rupture, impending rupture, malperfusion). The follow-up rate was 95.4%, with a mean follow-up of 43.8 ± 36.4 months. The largest diameters of the minor and major axes were measured on computed tomography at admission and before discharge. All causes of mortality, late aortic events, and operation and indication for operation for dissected aorta were assessed with the Kaplan-Meier method. Logistic regression was used to examine whether aortic diameter is useful in predicting late aortic events. Cox regression was carried out to assess the prognostic effect of aortic diameter after allowing significant covariates, and receiver operating characteristic analyses were used to determine test reliability. In-hospital mortality was one (0.6%). Long-term mortality was 26 (14.9%). There were 42 patients (24.1%) who underwent late operation for dissected aorta, and 26 patients (14.9%) refused late operation despite a dissected aneurysm of 55 mm or saccular aneurysm. The rate of freedom from these aortic events was 73.5%, 61.2%, and 53.9% at 1 year, 3 years, and 5 years. Receiver operating characteristic analyses showed cutoff values at admission of 40 mm for minor axis diameter with sensitivity of 72.1% and specificity of 83.2% (area under the curve [AUC], 0.81; P < .001) and 41 mm for major axis diameter (AUC, 0.80; P < 0.001); cutoff values before discharge were 39 mm for minor axis diameter (AUC, 0.83; P < .001) and 42 mm for major axis diameter (AUC, 0.85; P < 0.001). After adjustment for other covariates (age, sex, ulcerlike projection, and larger false lumen diameter), minor axis aortic diameter at admission of 40 mm was an independent risk factor of late aortic events (hazard ratio, 4.55, 95% confidence interval, 2.58-8.32; P < .001). We identify minor axis diameter of 40 mm on computed tomography at admission as the optimal aortic diameter for prediction of late aortic events.