Role of Non-Invasive Hemodynamic Forces through Four-Dimensional-Flow Magnetic Resonance Imaging (4D-Flow MRI) in Evaluating Mitral Regurgitation with Preserved Ejection Fraction: Seeking Novel Biomarkers

Featured Application: Emphasizing the potential of hemodynamic force as a biomarker of MR evaluation. Mitral regurgitation (MR) is the systolic retrograde flow from the left ventricle (LV) to the left atrium. Despite the recognized importance of hemodynamic force (HDF) in cardiology, its exploration in MR has been limited. Therefore, we aimed to explore non-invasively assessed HDF as a novel biomarker for evaluating MR utilizing 4D-flow MRI. The study cohort comprised 15 healthy controls (19-61 years, 53% men) and 26 MR patients with preserved ejection fraction (EF) (33-75 years, trivial-severe, 54% men). The HDF analysis involved the semi-automatic calculation of systolic-diastolic root mean square (RMS), average, and transverse/longitudinal ratio across three directions (S-L: septal-lateral, I-A: inferior-anterior, and B-A: basal-apical) using Segment, v2.2 R6410 (Lund, Sweden, Medviso). A noticeable trend shift emerged in HDF as the MR severity increased (p-value < 0.05). The MR severity demonstrated a noteworthy correlation with systolic RMS B-A, average B-A, diastolic average B-A, systolic average S-L, B-A, and systolic-diastolic ratio (rho = 0.621, 0.457, 0.317, 0.318, 0.555, -0.543, -0.35, respectively; p-value < 0.05). HDF significantly correlated with LV function (end-diastolic volume, end-systolic volume, EF, and mass; p-value < 0.05). Systolic RMS B-A and diastolic RMS S-L emerged as significant predictors of MR (Beta, 95% CI [3.253, 1.204-5.301], [5.413, 0.227-10.6], p-value < 0.05). This study emphasizes HDF as a potential hemodynamic biomarker for evaluating MR.