Left atrial size increases with body mass index in children

Objectives: To evaluate the association between body mass index (BMI) z-score and left atrial (LA) size in childhood and to determine whether LA size differs between healthy weight (HW), overweight (OW) and obese (OB) children.

Background: LA enlargement is an independent risk factor for adverse cardiovascular outcomes. BMI is associated with LA size in adults but this may be mediated by co-morbidities that accompany adult obesity. Thus the relationship between LA size and BMI z-score in children is of interest, to assess the effect of increased body mass per se.

Methods: 991 children aged 5-15 years (9.3+/-2.8 years, 60% male), with normal cardiac structure and function, were studied by ultrasound. LA diameter (indexed to height) was measured and regression analysis assessed the association with possible determinants.

Results: Indexed LA diameter was significantly associated with BMI z-score (r=0.239), age (r=0.282), left ventricular (LV) posterior wall (LVPW) thickness (r=0.125) and LV mass index (r=0.349) (p<0.001 for all). On multivariate analysis, BMI z-score was significantly related to Indexed LA diameter after controlling for age, sex and LV mass index or LVPW thickness. Indexed LA diameter increased across weight groups [19.8+/-2.9, 20.5+/-2.8 and 21.9+/-3.3 mm/m for HW, OW and OB, respectively (p<0.001)].

Conclusions: In children, higher BMI z-score is an independent determinant of increased LA size, suggesting that obesity exerts an effect on LA size at an early age and thus potentially predisposes to later cardiovascular morbidity.