Impact of age, sex and ethnicity on intra-cardiac flow components and left ventricular kinetic energy derived from 4D flow CMR

Background: Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) allows quantification of left ventricular (LV) blood flow. We aimed to 1) establish reference ranges for 4D flow CMR-derived LV relative flow components and kinetic energy parameters indexed to end-diastolic volume (KEi _EDV) among healthy Asian subjects, 2) assess effects of age and sex on these parameters, and 3) compare these parameters between Asian and Caucasian subjects. Methods: 74 healthy Asian subjects underwent cine and 4D flow CMR. Relative flow components (direct flow, retained inflow, delayed ejection flow, residual volume) and multiple phasic KEi _EDV (LV global, peak systolic, systolic, diastolic, peak E-wave, peak A-wave) were analyzed. Sex- and age-specific reference ranges were reported. Results: Relative flow components and systolic phase KEi _EDV did not vary with age. Women had higher retained inflow and peak E-wave KEi _EDV, lower residual volume, peak systolic and systolic KEi _EDV than men. Peak A-wave KEi _EDV increased significantly (r = 0.474) whereas peak E-wave KEi _EDV (r = −0.458) and E-wave/A-wave ratio (r = −0.528) decreased with age. A sub-population (n = 44) was compared with 44 sex- and age-matched Caucasian subjects: no significant group differences were observed for all 4D flow CMR parameters. Conclusion: Asian sex- and age-specific 4D flow CMR reference ranges were established. Sex differences in retained inflow, residual volume, peak systolic, systolic KEi _EDV and peak E-wave KEi _EDV were observed. Ageing influenced diastolic KEi _EDV but not systolic phase KEi _EDV or relative flow components. All studied parameters were similar between sex- and age-matched Asian and Caucasian subjects, implying generalizability of the ranges.