Quantitative 4D flow MRI assessment of left ventricular hemodynamics in bicuspid aortic valve across regurgitation severities and its association with myocardial deformation.

Bicuspid aortic valve (BAV) extends beyond aortic valve and wall disease, also affecting the left ventricle (LV). It leads to energetic alterations, myocardial deformation, and diastolic dysfunction, which are further exacerbated by persistent aortic regurgitation. As such, we aimed to assess LV dynamic reciprocal energy adjustments and their association with structural remodeling in BAV considering regurgitation severities. Seventy-six individuals who underwent 4D flow magnetic resonance imaging (4D Flow MRI) were recruited, including 29 BAV patients without valvular complications, 12 with mild, and 12 with moderate to severe aortic regurgitation, as well as 23 healthy controls. Kinetic energy, viscous energy loss (EL), its ratio at early and late filling timepoints (EL E/A), and viscous EL index were computed. Additionally, 3D LV strain parameters were derived from balanced steady-state free precession cine images using feature tracking. Kruskal-Wallis H test and one-way ANOVA for group comparisons, along with Spearman’s rho for correlations, were used. Metrics at late-filling demonstrated group differentiation, whereas early-filling metrics did not. Peak diastolic strain rate (PDS Rate) circumferential were considerably lower in regurgitant BAV compared to those without complications and controls (p < 0.001). EL E/A distinguished all BAV subgroups from healthy control. Among the hemodynamic parameters, viscous EL E/A showed significant correlations with LV mass and PDS Rate circumferential (rho=-0.47 and rho = 0.49, respectively; p < 0.001). 4D Flow MRI-derived viscous EL E/A may represent an early hemodynamic biomarker of diastolic dysfunction, demonstrating superior sensitivity to strain analysis, although validation in broader cohorts remains warranted.