2.8 Relationships Between Adiposity and Left Ventricular Function in Adolescents: Mediation by Blood Pressure and other Cardiovascular Measures

Abstract

Introduction

Increased adiposity is associated with poorer left ventricular (LV) function but the mediating role of blood pressure (BP) and other cardiovascular measures is unknown. We investigated the roles of potential mediators in adolescents in a UK birth cohort, the Avon Longitudinal Study of Parents and Children.

Methods

Fat and lean mass were assessed by dual energy X-ray absorptiometry (DXA) in 2,068 individuals (age 17.7(SD 0.32) years; 45% male; weight 67(SD 13) kg). BP was measured and echocardiography performed. Tissue Doppler systolic (s’), early diastolic longitudinal function (e’) and transmitral E/A were used as measures of LV systolic and diastolic function respectively. Mediation was estimated using structural equation modelling; height, sex, socioeconomic position, lean mass and smoking were included as potential confounders in all models.

Results

Table 1 shows the total and direct (total – indirect (mediated)) effects (standardized β) for each potential mediator, alongside %mediation. No convincing associations were found between fat mass and s’ or e’.

Conclusions

MAP, HR and EDV, an indicator of preload, are important mediators of the effect of adiposity on diastolic function in adolescence, while TPR appears to account for none of the effect. Absence of mediation by PP, in combination with the mediation by TAC, suggests that stroke volume contributes some mediative effect. These findings emphasise the importance of adiposity and risk factor control in adolescence.

Table 1 Mediation of the association between fat mass and E/A