The effects of aging on left ventricular diastolic function evaluated with 4D flow MRI: a novel approach using mitral velocity and propagation velocity measurements.

OBJECTIVE: Assessing diastolic function (DF) using 4D-Flow MRI may offer valuable physiological insights during left ventricular (LV) filling. We aimed to test DF parameters typically obtained with echocardiography (TTE) but derived from 4D-Flow MRI, including inflow velocity, flow filling rate, and propagation velocity (VP), by characterizing LV diastolic filling associated with aging. Approach: Sixty healthy volunteers (34 women, 26 men; mean age, 52±18 years; range: 20-80 years) underwent cardiac 4D-Flow MRI and TTE as part of cardiac ageing studies. Early (E) and atrial (A) mitral inflow peak velocities were obtained at the leaflet tips with and without normal projection (E and ALT_PROJ, E and ALT_NON-PROJ). Peak early and atrial filling rates (PEFR, PAFR) were derived from flow curves. VP was calculated mimicking TTE approach (VP_SLOPE) and by taking the slope of a plane fitting the velocity curves on a 3D streamline within the LV (VP_PLANE). Associations between age, velocity-derived indices related to DF and LV geometry were assessed. Main results: All 4D-Flow velocity parameters were associated with age (p<0.001). E/ALT_NON-PROJ and E/ALT_PROJ ratios correlated with TTE (r=0.69 and r=0.67 respectively, p<0.001). PEFR showed a stronger inverse association with age (r=-0.75, p<0.001) than TTE peak velocities (r=-0.19, p=0.149). VP_PLANE correlated better with age (r=-0.47, p<0.001) than VP_SLOPE (r=-0.26, p<0.05) and with indicators of DF such as E/E'TTE, PEFR/PAFR ratio and PEFR normalized to filling volume. Significance: Indices derived from 4D-Flow MRI were sensitive to age-related variations in LV filling dynamics, indicating potential for validation in pathological cohorts with confirmed diastolic dysfunction. .