The length of the fusion between leaflets in bicuspid aortic valve is independently related to ascending aorta dilation and flow dynamics alterations assessed by 4D-flow CMR

Abstract Background Aortic dilation in bicuspid aortic valve (BAV) patients has been related to altered flow patterns, which contribute to aortic wall degeneration. However, preventive aortic replacement is currently based on a diameter threshold. Several studies on excised BAV reported wide variability of fusion extent. Purpose To unveil whether leaflet fusion extent can be quantified by CMR and is related to aortic dilation and flow abnormalities in non-dysfunctional BAV. Methods One hundred and twenty adults with non-dysfunctional BAV and no previous aortic or aortic valve surgery and 28 healthy volunteers underwent double-oblique cine and 4D flow CMR. BAV patients with two sinuses of Valsalva or left and non-coronary cusps fusion were excluded. Peak systolic circumferential wall shear stress (WSSc) and pulse wave velocity (PWV) in the ascending aorta (AAo) were assessed by 4D flow CMR. Fusion length between leaflets was measured using a stack of double-oblique cine CMR images of the aortic valve. Results The length of the fusion was effectively measured in 112/120 (93%) patients with good reproducibility (ICC = 0.826) and showed great variability (range 2.3–15.4 mm, 7.8±3.2 mm and tertiles cut-off points 6 and 9.3 mm). In multivariate analysis adjusted for clinical and demographic characteristics and PWV, fusion length was independently associated with the diameter at the sinus of Valsalva (p=0.002) and the AAo (p=0.02) (Table). WSSc progressively increased with larger fusion length (Figure), with statistical significance (p