Body Fat Distribution, Overweight, and Cardiac Structures in School‐Age Children: A Population‐Based Cardiac Magnetic Resonance Imaging Study

BACKGROUND: Adiposity is associated with larger left ventricular mass in children and adults. The role of body fat distribution in these associations is not clear. We examined the associations of body fat distribution and overweight with cardiac measures obtained by cardiac magnetic resonance imaging in school‐age children. METHODS AND RESULTS: In a population‐based cohort study including 2836 children, 10 years of age, we used anthropometric measures, dual‐energy X‐ray absorptiometry, and magnetic resonance imaging to collect information on body mass index, lean mass index, fat mass index, and abdominal visceral adipose tissue index. Indexes were standardized by height. Cardiac measures included right and left ventricular end‐diastolic volume, left ventricular mass, and mass‐to‐volume ratio as a marker for concentricity. All body fat measures were positively associated with right and left ventricular end‐diastolic volumes and left ventricular mass, with the strongest associations for lean mass index (all P<0.05). Obese children had a 1.12 standard deviation score (95% CI, 0.94–1.30) larger left ventricular mass and a 0.35 standard deviation score (95% CI, 0.14–0.57) higher left ventricular mass‐to‐volume ratio than normal weight children. Conditional on body mass index, higher lean mass index was associated with higher right and left ventricular end‐diastolic volume and left ventricular mass, whereas higher fat mass measures were inversely associated with these cardiac measures (all P<0.05). CONCLUSIONS: Higher childhood body mass index is associated with a larger right and left ventricular size. This association is influenced by higher lean mass. In childhood, lean mass may be a stronger determinant of heart growth than fat mass. Fat mass may influence cardiac structures at older ages.