The Initial Aortic Diameter as the Predictors of Aortic Events in Uncomplicated Type B Aortic Dissection

Abstract

Introduction: Several past studies investigated to detect the risk factors of late aortic events for patients with uncomplicated acute Type B aortic dissection. The initial aortic diameter was reported as a risk factor for late aortic events. However, it remains controversial about the cut off values; 40mm or 45mm. We evaluate the optimal initial aortic diameter for a risk factor. Methods: We conducted a retrospective cohort study reviewing 216 consecutive patients underwent initial treatment for uncomplicated acute type B aortic dissection between 2004 and 2018. We excluded 50 complicated cases (rupture, impending rupture and malperfusion). We evaluated the incidences of aortic events (operation for dissected aorta or operative indication for dissected aorta) after initial therapy. Follow up rates was 90.7% with median follow-up of 42 months. The largest minor and major axes diameters were measured on computed tomography at admission, before discharge. Logistic regression was used to examine whether aortic diameter was useful in predicting late aortic events. Cox regression was carried out to assess the prognostic effect of aortic diameter after allowing for significant covariates and receiver operating characteristic (ROC) analyses were used to determine test reliability. Moreover, patients were categorized into 3 groups based on the largest minor axis aortic diameter at admission; 40mm > Group A, 45mm > Group B ≥ 40mm, Group C ≥ 45mm, and Kaplan-Meier analyses detected the incidences of aortic events among these three groups. Results: In hospital mortality was 1 (0.5%). Long-term mortality was 40 (18.6%). Aortic events were 82 (38.1%). ROC analyses showed the cut-off values 40mm of minor axis diameter at initial CT (Area under the curve, 0.77, p< 0.01). In the multivariate analysis, risk factors of aortic events were initial aortic diameter ≥ 40mm (HR 4.21, 95% CI 2.54-6.98, p< 0.01), the false lumen diameter > the true lumen diameter (HR 3.73, 95%CI 1.88-7.41, p< 0.01), ulcer like projection (HR 1.83, 95%CI 1.04-3.22, p=0.04) and age ≥ 70 (HR 2.01, 95%CI 1.22-3.33, p= 0.01) were shown to be independent risk factors of late aortic events. The 3-years incidences rates of aortic events were 22.3% in Group A, 47.5% in Group B, and 87.9% in Group C, respectively (p< 0.01). Conclusion: We identify the optimal aortic diameter for predictor of aortic events was 40mm at admission. The larger initial aortic diameter, the more likely patients were to experience aortic events. We should closely monitor them and consider intervention at appropriate time. Disclosure: Nothing to disclose