The proximal extension of acute type A aortic dissection is associated with ascending aortic wall degeneration.

Background: Aortic root involvement during acute type A aortic dissection (ATAAD) may depend on ascending aortic wall degeneration. Surgical decision-making for extended resection of the aortic root is clinically made without histopathology. The aim of the study was to investigate whether the degree of degeneration of the ascending aortic wall found in patients with ATAAD is associated with the aortic root involvement. Methods: Collectively, 141 consecutive patients undergoing ATAAD surgery at Tampere University Heart Hospital were investigated. The ascending aortic wall resected in surgery was processed for 11 different variables that describe medial and adventitial degeneration. In addition, atherosclerosis and inflammation were separately evaluated. Patients undergoing aortic root replacement were compared with those with supracoronary reconstruction of the ascending aorta with/without aortic valve surgery (root-sparing surgery) during a mean 4.9-year follow-up. Results: Aortic root replacement together with the ascending aortic replacement was performed in 39% of the patients (n=55). The mean age for all patients was 65 years [standard deviation (SD 13)]. Many patients with aortic root replacement had moderate to severe aortic valve regurgitation (85.5%). Most of the patients with aortic root-sparing surgery included a supracoronary tube prosthesis (89.5%), while nine patients also had aortic valve replacement. The degree of mucoid extracellular matrix accumulation was more prominent in patients with aortic root replacement compared to patients with root-sparing surgery (2.1 SD 0.4 Conclusions: Histopathology of the ascending aorta during ATAAD reveals distinctive aortic wall degeneration in patients with aortic root involvement