Abstract 13593: Global Aortic Stiffness in Bicuspid-associated Aortopathy is Independent of Aortic Dimensions and Similar to Tricuspid Aortic Valve Control Subjects

Abstract

Introduction: Bicuspid aortic valve (BAV) carries high aortopathy risk, and debate exists about relative contributions of altered wall structure vs. BAV-mediated hemodynamics. Pulse wave velocity (PWV), a surrogate for stiffness, can be quantified from 4D flow MRI. Here we use PWV to study wall stiffness in a large cohort of BAV aortic dilatation patients and two control groups. Hypotheses: 1. abnormal thoracic aortic (Ao) wall biomechanics for BAV patients result in altered PWV compared to controls and 2. PWV correlates with Ao diameter. Methods: This retrospective IRB approved study included 483 subjects: 124 healthy (no known cardiovascular disease), 168 BAV patients with ascending Ao (AAo) dilatation—maximal-area AAo (MAA) or sinus of Valsalva (SOV) diameter ≥4cm—and 191 TAV AAo dilatation (see table). No subjects had valve stenosis or ejection fraction ≤50%. Global PWV was assessed from MRI by cross-correlating flow in 80-100 Ao cutplanes and median AAo diameter by geometric mesh analysis of 3D Ao segmentations. Results: In multivariate regression, older age was the most significant predictor of higher PWV (controls: 0.073 m/s / y; TAV: 0.072 m/s / y; BAV: 0.092 m/s / y; all p<1E-4). Increased Ao diameter in controls associated with higher PWV (0.10 m/s / mm, p=0.03). Both BAV and TAV patients had no association between any Ao diameter (MAA, SOV, median) and PWV (p≥0.1 for all metrics). Between subject groups in a given age range, no significant differences of PWV existed except in some younger groups (see image; p≤0.04 in some under-40y). Conclusion: Global Ao wall stiffness from PWV in BAV Ao dilatation patients has minimal/no significant difference from non-BAV control PWV, despite genetic factors and different wall structure in BAV patients. This suggests wall tissue differences of BAV patients do not coincide with globally altered Ao stiffness. However, BAV-mediated Ao flow changes manifest regionally, and further study of localized properties would be valuable.