Abstract 3637: Influence of Non-Hemodynamic Factors on Left Ventricular Mass in Adolescents with High Prevalence of Obesity: the Strong Heart Study.
Background: We have previosuly reported that in obese adolescents left ventricular (LV) mass (M) is disproportionately high compared to their hemodynamic load, suggesting that the increase in LVM might represent a response also to non-hemodynamic factors influencing LV growth. Whether non-hemodynamic factors influence LV growth in adolescents is unknown.
Methods: Data were obtained in 372 non diabetic adolescents (age 17 ± 1 years, 55% girls) from the Strong Heart Study. Obesity and Metabolic syndrome (MetS) were defined according to current guidelines for adolescents. Systolic blood pressure (pressure load) and Doppler stroke volume (volume load) were expressed as “stroke work” and were considered as hemodynamic determinants of LVM, together with heart rate. From this multivariate relation, unstandardized residuals of LVM were obtained and studied in multiple regression models including age, gender, height, serum creatinine and potential metabolic correlates (fasting glucose, plasma insulin, HDL cholesterol, tryglicerides, and waist circumference, considered individually or clustered in MetS).
Results: Obesity was found in 181 participants (49%) and MetS in 136 (37%). LVM was strongly correlated with stroke work (r2=0.51; p<0.0001), with no significant effect of heart rate. Residuals of this regression were studied with individual anthropometric and metabolic correlates. A mild effect of height could be recognized (p<0.05), whereas waist circumference was more strongly associated with LVM residuals ( r2=0.13; p<0.0001), with no independent association found for age, gender, insulin, creatinine and lipid profile. The association between residuals of LVM and waist circumference was not influenced by addition of MetS in the regression model.
Conclusions: In an unselected population of adolescents with high prevalence of obesity, a significant extent of LVM variability is not explained by hemodynamic load, age and gender. This unexplained LVM growth is significantly associated with waist circumference, without detectable effect for other metabolic factors (either individual or clustered as MetS). Central fat distribution appears to be the strongest non-hemodynamic stimulus to higher LVM in adolescents.