Predictors of Prognosis in Patients with Type B Aortic Dissection

Type B aortic dissection (TBAD) affects mostly men with an estimated annual incidence between 2.9 and 4.0 per 100,000, and it appears to be increasing. DISSECT classification was published in 2013 aiming to reunite clinical and anatomical characteristics of interest to clinicians involved in TBAD management. In Portugal, the incidence of the condition, as well as its characteristics and outcomes, are not well documented. The aim of this paper is to describe the reality of a tertiary institution with a referral area of about 0,6 million habitants.

It is a retrospective study that included all patients with TBAD admitted from March of 2006 to 2016. The patients were categorized according to their demographic and clinical characteristics. For each patient, the computerized tomography scan that enable the TBAD diagnosis was classified using DISSECT classification. Overall mortality rates and aorta-related mortality rates were estimated using Kaplan-Meier method. Cox regression was used to study determinants of mortality.

We included 35 patients, estimating a TBAD incidence of approximately 0.6 per 100,000 person-year. The majority were men (83%) with a mean age of 60±12 years-old; 71% were hypertensive, 56% were ex-smokers or active smokers and 13% had diabetes. As to DISSECT classification, 76% were acute (Duration), 66% had a primary Intimal tear location in aortic arch, the maximum trans-aortic diameter was 44±13mm (Size), 60% extended from aortic arch to abdomen or iliac arteries (Segmental extent), 26% presented with Complications, being rupture and branch vessel malperfusion the most frequent, and 28% had partial Thrombosis of false lumen (versus 66% with permeability of false lumen). Eight patients underwent surgery (24%), 6 of them in acute phase and 2 of them in subacute phase. At 12 months, overall survival of whole series was 73,1%±8,3% and survival free from aortic-related mortality was 83±6,7% (Figure 1 A and B). The presence of complications was identified as an independent risk factor of overall mortality but not to aortic-related mortality.

The incidence of TBAD verified was lower than what has been described in literature. DISSECT classification can be easily applied to TBAD cases. The presence of complications predicts higher mortality. Further studies are needed to characterize TBAD in Portugal.