Systematic Morphological Assesment of the Ascending Aorta Dissection: Application of Cardiovascular Pathology...

This study investigated the distinguishing characteristics between acute type A aortic dissection (ATAAD) and aortic wall dilatation. Utilizing systematic histopathology criteria from the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology consensus statement, the analysis focused on degeneration, atherosclerosis, and inflammation in patients undergoing surgery in a Finnish tertiary care hospital. The study included 156 patients, those undergoing surgery for ATAAD (n = 116) and those with dilatation (n = 40). Despite similar clinical characteristics, histological analysis of the aortic wall indicated a higher overall degeneration in ATAAD compared to dilatation (2.4 ± 0.6 vs. 1.9 ± 0.8, Point score unit (PSU), p < 0.001). Findings included increased intralamellar mucoid extracellular matrix accumulation (69 vs. 32, p = 0.020; extent 2.0 ± 0.3 vs. 1.7 ± 0.5, PSU, p < 0.001; severity 1.8 ± 0.6 vs. 1.5 ± 0.5, PSU, p = 0.005) elastic fiber thinning (68 vs. 9, p = 0.001; extent 1.0 ± 0.9 vs. 0.4 ± 0.8, PSU, p < 0.001; severity 0.8 ± 0.8 vs. 0.4 ± 0.8, PSU, p = 0.001), elastic fiber disorganization (89 vs. 21, p = 0.005; extent 1.2 ± 0.8 vs. 0.9 ± 0.9, PSU, p = 0.029) and laminar medial collapse (64 vs. 6, p < 0.001; type 0.7 ± 0.7 vs. 0.2 ± 0.4, PSU, p < 0.001; extent 0.9 ± 0.9 vs. 0.9 ± 0.9, PSU, p < 0.001) in ATAAD compared to dilatation. Elastic fiber pathology and laminar medial collapse are distinct features of ATAAD compared to aortic dilatation in patients undergoing ascending aorta surgery.