EFFECT OF LEAN BODY-MASS, FAT MASS, BLOOD-PRESSURE, AND SEXUAL-MATURATION ON LEFT-VENTRICULAR MASS IN CHILDREN AND ADOLESCENTS - STATISTICAL, BIOLOGICAL, AND CLINICAL-SIGNIFICANCE

Background Left ventricular hypertrophy has been established as an ind ependent risk factor for the development of cardiovascular morbidity a nd mortality. It is clear that left ventricular mass increases during childhood and adolescence with body growth. The extent to which other factors, such as obesity, stage of sexual maturation, and level of blo od pressure, determine left ventricular mass has been controversial. M ethods and Results The study was a cross-sectional evaluation of the r elationship of left ventricular mass determined by echocardiography wi th lean body mass and fat mass determined by dual-energy x-ray absorpt iometry, which is the most valid and reliable method for determination of body composition in children and adolescents. The relationship of left ventricular mass with the stage of sexual maturation and with sys tolic and diastolic blood pressure was also evaluated. Two hundred one subjects (105 boys, 96 girls, 103 white and 98 black) 6 to 17 years o ld were studied. Age (r=.72), height (r=.81), weight (r=.84), body sur face area (r=.87), sexual maturation (r=.75), lean body mass (r=.86), fat mass (r=.54), systolic BP (r=.58), and diastolic BP (r=.48) were a ll univariate correlates of left ventricular mass. In a multiple regre ssion analysis, only lean body mass, fat mass, and systolic blood pres sure were statistically significant independent correlates of left ven tricular mass. Lean body mass alone explained 75% of the variance of l eft ventricular mass, whereas fat mass and systolic blood pressure exp lained only 1.5% and 0.5% of the variance, respectively. Lean body mas s was the strongest determinant of left ventricular mass in all four r ace-sex groups. Conclusions This study provides an opportunity to sepa rate the effects on left ventricular mass of lean body mass resulting from linear growth from those of fat mass resulting from obesity. Lean body mass, fat mass, and systolic blood pressure all have a statistic ally significant independent association with left ventricular mass, s uggesting that all three play an important biological role in determin ing left ventricular mass. However, fat mass and systolic blood pressu re have only a small impact on left ventricular mass. This indicates t hat fat mass and blood pressure would be expected to be of only minor clinical Importance in determining left ventricular children and adole scents.