Association between left atrial size and measures of adiposity among normal adolescent boys.

Obesity (OB) in adults is associated with insulin resistance, hypertension, and left atrial (LA) enlargement. This study aimed to determine the association between LA size and (1) different components of the metabolic syndrome (body mass index [BMI], waist circumference [WC], insulin levels, lipid levels, and blood pressure), and (2) left ventricular (LV) diameters and diastolic function. Data were collected cross-sectionally from 142 healthy adolescent boys age 16.8 ± 2.0 years in 2009. Measurements of BMI, WC, blood pressure, lipid profile, and insulin were performed. Mode M, two-dimensional Doppler echocardiography was performed. Measurements of LA area, LV end diastolic diameter (EDD), end systolic diameter (ESD), posterior wall, interventricular septum (IVS), and shortening fraction were performed. Tisular Doppler of the diastolic mitral annular E wave (DTE) and A wave (DTA) and the ratio of maximal early diastolic filling wave velocity to maximal early diastolic myocardial velocity (E/e') were recorded. The study group included 38 OB boys (26.8%) and 32 overweight boys (22.5%). Significant univariate association was found between LA area and BMI (r = 0.61), WC (r = 0.56), systolic blood pressure (r = 0.21), insulinemia (r = 0.28), high-density lipoprotein-cholesterol (HDL-C) (r = -0.24), triglycerides (r = 0.20), EDD (r = 0.25), LV posterior wall (r = 0.25), IVS (r = 0.25), DTE (r = 0.27), DTA (r = 0.30), and E/e' (r = -0.28). Multiple linear regression analysis showed that LA area was associated with BMI (B = 0.61; R (2) = 0.47) adjusted for confounding variables. In adolescents, BMI and WC were significantly associated with LA, suggesting that OB could be associated with LA enlargement as early as adolescence.

Influence of obesity and insulin resistance on left atrial size in children.

BACKGROUND: Left atrial (LA) enlargement has been linked to obesity and insulin resistance in adults. OBJECTIVE: The purpose of this study was to determine the association in children between LA area and: (i) different components of the metabolic syndrome including obesity (OB), measures of body mass index (BMI) and waist circumference (WC), homeostasis model assessment-insulin resistance (HOMA-IR, proinsulin), and blood pressure (BP); and (ii) left ventricular mass (LVM) and diastolic function, measured using echo Doppler. METHODS AND RESULTS: Eighty-four (44 females) subjects, [40 OB (BMI>95%), 28 overweight (BMI>85%)], 16 non-OB (BMI<85%)] aged 9+/-2.24 yrs were matched for sex and age. BMI, WC, BP, Tanner stage, and Mode M, 2-dimensional and Doppler transmitral echocardiography were assessed. A standard oral glucose tolerance test (OGTT) was done, measuring glucose, insulin, and proinsulin concentrations. Hypertension was only present in OB subjects (25%). Significant univariate association (p<0.001) was found between LA area and height (r=0.52), age (r=0.45), Tanner stage (r=0.45), BMI (r=0.66), WC (r=0.70), systolic BP (r=0.52), diastolic BP (r=0.53), proinsulin (r=0.36), and HOMA-IR (r=0.36). In the multivariate regression analysis, independent variables were entered in a stepwise fashion: initially, gender (p=0.006) and Tanner stage (p=0.011) were still significant independent correlates of LA area after adjusting for age, gender, and Tanner stage. Subsequently, incorporation of WC showed that WC (p=0.018) was a significant independent correlate of LA area. A larger model constructed to test the significance of adjustment factors, including WC, BP, LVM, and HOMA-IR showed that WC (p<0.001) was the only significant independent variable. CONCLUSION: LA enlargement is present in childhood and is related to abdominal OB and insulin resistance, suggesting that children with central OB are at increased risk for cardiovascular disease.