The elusive link between aortic wall histology and echocardiographic anatomy in bicuspid aortic valve: implications for prophylactic surgery

OBJECTIVE: Prediction of aortic dissection or rupture is extremely difficult in patients with bicuspid aortic valve. We aimed to identify clinical and echocardiography predictors of histological abnormalities of the aortic wall in patients with bicuspid aortic valve undergoing aortic surgery. METHODS: We assessed the histology of the aortic wall and clinical and echocardiography variables in a cohort of patients with bicuspid aortic valve (n = 127) and a wide spectrum of valvar disease who underwent replacement of the ascending aorta (with or without aortic valve surgery). Histology was classified using a 5-grade system developed by Larson and Edward. RESULTS: Histological alterations of the aortic wall were absent/mild (grade 0-1) in 77 patients (61%) and moderate/severe (grade 2-3) in 50 (39%). Patients with moderate/severe histological alterations were younger (47 ± 17 vs 53 ± 16; p = 0.042). Eighteen patients out of 48 (38%) with an ascending aorta diameter ≤ 4.5 cm had grade 2-3 aortic wall disease as did 8 out of 18 (44%) with a diameter ≤ 4 cm. Nineteen out of 46 (41%) patients with a maximal ascending aortic area/height ratio < 10 cm(2) m(-1) had moderate/severe histological alterations. Multivariate logistic regression analysis showed that the indexed diameter of the aortic annulus was significantly associated with grade 2-3 aortic wall disease (odds ratio (OR): 12.22, 95% confidence interval (CI): 1.65-90.38, p = 0.014). CONCLUSIONS: A high proportion of patients with bicuspid aortic valve and mild to moderate aortic dilatation have severe histological abnormalities of the aortic wall that are not predictable by clinical and echocardiographic findings. These observations suggest that risk stratification for aortic dissection or rupture in patients with bicuspid aortic valve is so far quite suboptimal and future investigations are warranted.