EFFECT OF BODY-SIZE, PONDEROSITY, AND BLOOD-PRESSURE ON LEFT-VENTRICULAR GROWTH IN CHILDREN AND YOUNG-ADULTS IN THE BOGALUSA HEART-STUDY

Background The measurement of left ventricular mass (LVM) is important because individuals with increased LVM are at increased risk for cardiovascular diseases, including myocardial infarction and congestive heart failure. There are limited longitudinal data on the acquisition of LVM in children and young adults and the relative importance of sex, growth, excess body weight, and blood pressure (BP) on change in LVM. Methods and Results The study cohort consisted of a cross section of 160 healthy children and young adults 9 to 22 years of age at first exam in the biracial community of Bogalusa, La. All had stable BP levels recorded over a 2- to 3-year period. Repeated examinations were performed 4 to 5 years apart. At each exam, 6 BPs were obtained with a mercury sphygmomanometer by trained examiners. The mean of the observations was used, with the fourth Korotkoff phase serving as the measure of diastolic BP. Anthropometric data, including height (HT), weight (WT), and triceps skin fold thickness (TSF), were also obtained, and M-mode echocardiograms were performed. Ponderal index (PI=WT/HT3) was used as a measure of weight-for-height. Tracking of HT (r=.68 to .76), WT (r=.73 to .82), PI (r=.77 to.89), TSF (r=.70 to .80), BP (r=.47 to .60), and LVM (r=.40 to .70) was strong in both series (P<.0001). LVM indexed for linear growth (LVM/HT2.7) tracked in females (r=.56, P<.0001) but not in males. In univariate cross-sectional analyses, LVM/HT2.7 correlated with WT, PI, and TSF in both sexes (r=.21 to .60, P<.05) and with systolic BP (SEP) in females (r=.23, P<.05). WT was the only independent correlate of LVM/HT2.7 in both sexes in multivariate cross-sectional analysis in a model containing age, SEP, WT, and TSF as independent variables (r(2)=.08 to .28, P<.02). In longitudinal univariate analyses, initial measurements of WT, PI, and TSF predicted final LVM/HT2.7 in both sexes (r=.28 to .56, P<.01), and SEP was significant for females (r=.27, P<.05). In multivariate analyses, initial WT was associated with final LVM and LVM/HT2.7 in both sexes (r(2)=.27 to .54, P<.01). Finally, baseline LVM correlated with final SEP in both sexes (r=.21 to .27, P<.05), and initial LVM/HT2.7 correlated with final SEP in females (r=.26, P<.05) with a trend for males (r=.17). Conclusions These data indicate that linear growth is the major determinant of cardiac growth in children and that excess weight may lead to the acquisition of LVM beyond that expected from normal growth. Increased mass may also pre cede the development of increased BP. The development of obesity may therefore be a significant, and possibly modifiable, risk factor for developing left ventricular hypertrophy and hypertension, risk factors for cardiovascular morbidity and mortality.