Abstract 14914: Advanced 4D-flow Measurements of Aortic Forward Flow, Reverse Flow, and Stasis in Bicuspid Aortic Valve Patients Without Aortic Stenosis or Regurgitation

Abstract

Introduction: Precise analysis of aortic hemodynamics is crucial in the study of bicuspid aortic valve (BAV) disease. This study provides a comprehensive evaluation of aortic forward flow (FF), reverse flow (RF) and stasis in BAV patients using novel 3D-based techniques previously shown to be more accurate than traditional 2D analysis methods. Hypothesis: BAV patients without valve dysfunction show abnormal aortic FF, RF, and stasis compared to healthy controls. Methods: We recruited 44 BAV patients (48±15 yrs, 27% female) and 23 healthy controls (37±14 yrs, 35% female). Cardiac MRI at 3T was performed inclusive of 4D-flow imaging. Patients with any aortic stenosis (AS) or ≥mild regurgitation (AR) were excluded. Flow analysis was performed by segmented volumetric regions: left ventricular outflow tract (LVOT), ascending aorta (AAo), arch, proximal descending aorta (PDAo), and distal descending aorta (DDAo). In each region, forward flow (FF), reverse flow (RF) and stasis were averaged over the cardiac cycle on a voxel-by-voxel basis. Left ventricular (LV) end-diastolic volume, end-systolic volume and ejection fraction were also measured. T-tests (or non-parametric equivalent) compared differences in parameters between cohorts. Results: BAV patients were significantly older than controls (48±15 vs. 37±14 yrs; p=0.01) but exhibited no significant differences in LV measures. Patients showed reduced FF in the AAo (0.09±0.03 vs. 0.11±0.04 mL/cycle; p<0.01), but greater FF in all downstream regions (eg. PDA: 0.02±0.03 vs. 0.01±0.02 mL/cycle; p=0.01). RF was significantly elevated in patients in the AAo (0.06±0.02 vs. 0.02±0.02 mL/cycle; p<0.01). BAV patients exhibited significantly less stasis in every region except the DDAo (eg. AAo: 23±11 vs. 50±10 % of cardiac cycle). Conclusions: 3D-derived measurements of FF, RF, and stasis are significantly altered in the thoracic aorta of BAV patients in the absence of AS or AR.