Abstract 11756: Higher Body Mass Index is Associated with Left Ventricular Structural Change Even in Early Childhood

Abstract

Background: Left ventricular (LV) hypertrophy is an independent risk factor for adverse cardiovascular outcomes. Adulthood obesity is associated with concentric LV hypertrophy, but there is little information when LV structural change begins to appear. To clarify this, we examined the relationship between BMI z-score and LV mass-to-volume ratio from infancy to adolescence.

Methods: Echocardiography with tissue Doppler imaging was performed in 840 subjects aged 4 months to 20 years. Subjects were divided into 4 age groups: infants group, < 1year (n =212); preschool children group, 1 to 6 years (n = 258); school children group, 7 to 12 years (n = 267); and adolescents group, 13 to 20 years (n = 103). LV end-diastolic volume and LV mass were measured and LV mass-to-volume ratio was calculated. Using tissue Doppler imaging, myocardial performance index (MPI) and isovolumic relaxation time (IRT) were calculated.

Results: In the total study population, there were significant relationships between BMI z-score and systolic blood pressure (r = 0.45, p <0.01), heart rate (r = -0.13, p < 0.01), LV mass-to-volume ratio (r = 0.44, r <0.01), IRT (r = 0.19, p < 0.01), and MPI(r = 0.29, p <0.01). Within each group, LV mass-to-volume ratio increased significantly with BMI z-score (infants, r =0.20; preschool children, r = 0.43; school children, r = 0.40; and adolescents, r = 0.29, p <0.01, respectively). The increased LV mass-to-volume ratio was due to a greater increase in LV mass to LV end-diastolic volume. In multivariate analysis, BMI-z score and systolic blood pressure were independent determinants of LV mass-to-volume ratio (R2 = 0.347). MPI was significantly associated with LV mass-to-volume ratio in the school and adolescents groups (r = 0.28 and 0.31, p <0.01, respectively), but this association was not significant in the infants and preschool children groups.

Conclusion: Higher BMI is associated with concentric LV hypertrophy even in infancy, however, LV functional change is not present yet. Concentric LV remodeling plus LV functional change begins to appear in school children. Our data support prevention of obesity in early childhood because higher BMI is responsible for significant change in LV geometry in early life.