Left atrial size increases with body mass index in children

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.

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.

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.

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)].

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.