A New Mechanism by Which an Acute Type B Aortic Dissection Is Primarily Complicated, Becomes Complicated, or Remains Uncomplicated

Background. This study is to evaluate if different locations of the primary entry tear result in primary complicated, secondary complicated, or uncomplicated acute type B aortic dissection. Methods. Sixty-five patients were analyzed. Patients were stratified according to the location of the primary entry tear. Primary entry tears in axial computed tomographic scans at the upper circumference (180 degrees) of the distal aortic arch were defined as convex (group A) and the remaining as concave (group B). Detailed morphometry was done and the clinical outcome, including need for thoracic endovascular aortic repair, was evaluated. Results. Forty-two patients (group A) had the primary entry tear at the convexity and 23 patients (group B) had the primary entry tear at the concavity of the distal aortic arch. There was a significant difference with regard to the incidence of primary complicated type B aortic dissection (group A 21% vs group B 61%, p = 0.003) and with regard to the development of complications in group A (9 days; 9 to 37) versus group B (0 days; 0 to 13, p = 0.03). Cox regression analysis revealed a primary entry tear at the concavity to be the only independent predictor of primary or secondary development of a complicated acute type B aortic dissection (hazard ratio, 1.8; 95% confidence interval, 1.0 to 3.2). Conclusions. A primary entry tear at the concavity of the distal aortic arch is associated with a significant increase of the occurrence of complicated acute type B aortic dissection. Due to low procedural risk and high success rates, closure of the primary entry tear with thoracic endovascular aortic repair is strongly recommended in this newly defined high-risk subgroup of patients. (Ann Thorac Surg 2012;93:1215-22) (C) 2012 by The Society of Thoracic Surgeons