Purpose:
The aim of this study was to identify risk factors associated with cardiac structure in a cohort of African American adolescents oversampled for obesity and high blood pressure (BP). Additional associations of cardiac structure with a pro-inflammatory adipokine profile (low adiponectin, elevated IL6, PAI-1 and CRP) were sought.
Methods:
A cross-sectional study was conducted using a two-by-two factorial design with four groups of African American adolescents based on BP (prehypertension or stage 1 hypertension=high BP) and body mass index (BMI > 95% =obese) designation. Measurements included: echocardiogram, anthropomorphics, BP (on 3 separate occasions), high sensitivity CRP and plasma adipokines (adiponectin, IL6, PAI-1). Standardized echocardiogram measurements were used to obtain left ventricular mass index (LVMI, g/m
2.7
) and left atrial diameter index (LADI, mm/m
2
). Ordinary least-squares regression with model selection by Mallow's Cp was used to determine if pro-inflammatory adipokine profile predicted LV mass and LA diameter in models including age, gender, BMI z-score, and systolic BP.
Results:
Data on 251 African American adolescents, ages 13-19, were analyzed. BMI-z score was strongly associated with a pro-inflammatory adipokine profile whereas high BP was not. Variation in LADI was significantly associated with BMI (β=0.12, p<0.01) and female gender (β=0.08, p=0.04). LVMI variation was significantly associated with BMI (β=3.53, p<0.01), age (β=0.71, p<0.01), female gender (β=-4.32, p<0.01), and systolic BP (β=0.10, p=0.03). Though significant in univariate models, inflammatory markers were not significantly associated with LADI or LVMI after BMI adjustment.
Conclusions:
In African American adolescents, BMI is an important determinant of LADI and LVMI. Obesity is associated with a pro-inflammatory adipokine profile but LADI and LVMI are not.
Table.
Regression modeling results after variable selection by Mallow C
p
: Left Atrium Diameter Index and Left Ventricular Mass Index (N = 251)
LADI
LVMI
Estimate (95% CL)
p-value
Estimate (95% CL)
p-value
Age (yr)
0.00063 (-0.021, 0.023)
0.955
0.71 ( 0.18, 1.24)
0.009
Gender (F)
0.08 ( 0.01, 0.16)
0.036
−4.32 (-6.13,-2.51)
<.001
BMI z-score
0.12 ( 0.08, 0.16)
<.001
3.53 ( 2.66, 4.40)
<.001
Systolic BP
0.0019 (-0.0017, 0.0055)
0.306
0.0952 ( 0.0085, 0.1819)
0.032