Sex differences in the histopathology of acute type A aortic dissections

Background: While sex-related differences in cardiovascular surgery outcomes have increasingly garnered attention in the past decades, knowledge about sex disparities in the pathophysiology of acute type A aortic dissections (ATAADs) remains sparce. In this study, we evaluate the histopathologic and atherosclerotic lesions in female and male ATAAD patients. Methods: A total of 68 patients were studied: 51 ATAAD patients (mean age 62.5 ± 10.8 years, 49% women) and 17 control patients (mean age 63 ± 5.5 years, 53% women). Cardiovascular risk factors were assessed clinically. Intimal and medial histopathological features were systematically evaluated in all. Results: Compared to the control group, all ATAAD patients showed significantly more elastic fibre pathology, mucoid extracellular matrix accumulation, smooth muscle cell nuclei loss, and overall medial degeneration (p<0.0001). The intimal layer was significantly thinner in the ATAAD vs the control group (p<0.023), with the control group exhibiting significantly more progressive atherosclerotic lesions compared to the ATAAD patients. No difference in medial vessel wall pathology was seen between the sexes. As compared to male ATAAD patients, atherosclerotic lesions were more severe in female ATAAD patients, independent of age and the cardiovascular risk factor hypertension. Conclusions: All ATAAD patients had a significantly thinner intimal layer and significantly diseased middle media compared to the control patients. Our results suggest that the severity of medial aortic pathology is not sex-specific in ATAAD patients. Intimal differences between sexes could however be considered as a potential risk factor for the development of an aortic dissection.