Epicardial Adipose Tissue and Left Ventricular Hypertrophy as Indicators of Visceral Obesity and Predictors of Cardio-Vascular Diseases in Obese Children

Abstract

The prevalence of obesity in all age groups has increased dramatically over the past 30 years. Obesity rates in Egypt have reached 66%, being the fifth worldwide after American Samoa 93.5%, Kiribati 81.5%, USA 66.7%, and Germany 66.5%. The International Obesity Task Force (IOTF) stated that worldwide one in 10 children is overweight. The adverse medical and psychosocial effects of obesity in children have been well-established. Childhood obesity is associated with the development of several risk factors for heart disease, including hyperlipidemia, hyperinsulinemia and hypertension. Each of the mentioned factors can increase the CVD risk independently. Even after adjusting for these risk factors, obesity remains directly associated with CVD. Deaths due to CVD have been linked directly to obesity. Visceral adipose tissue predicts unfavorable cardiovascular and metabolic risk more than total adiposity. Epicardial fat tissue is clearly metabolically active and an important source of both pro and anti inflammatory adipokines which might significantly affect cardiac function and morphology. Epicardial adipose tissue is suspected to directly interact with the myocardial tissue. Recent evidences suggest that cardiac adiposity could locally modulate the morphology and function of the heart and works as an easy and reliable biomarker and therapeutic target. EAT and LVH were assessed as markers for cardiac adiposity and predictors for the risk of future CAD. This study aimed to evaluate obese children with epicardial adipose tissue and abnormal cardiac morphology via echocardiography as a reliable indicator of visceral obesity and its relation to the degree of obesity, lipid profile, arterial blood pressure and insulin resistance. The study included 98 obese children (defined as having BMI SDS >+2) aged between 4-15 years and 34 age and sex matched normal weight controls. In all subjects, anthropometric measurments were assessed in the form of weight, height and waist circumference. BMI was calculated and arterial blood pressure was assessed. Anthropometric and ABP assessments were made using standardized equipments and techniques. Three consecutive measurements were taken and the mean was recorded. All the measurements were blotted on gender specific growth charts developed by WHO, 2007. Blood samples were taken after 10 hours of fasting to assess serum total cholesterol, TGA, HDL-C, LDL-C, CRP, fasting glucose and fasting insulin levels using standardized laboratory techniques. Total cholesterol and HDL-C levels were assessed using CHOD-PAP method. TGA and FBS were assessed using quantitative enzymatic techniques. Fasting insulin was assessed using ELISA technique. CRP was assessed using latex-enhanced nephlometry technique. LDL-C was calculated and insulin resistance, too, was calculated according to HOMA module. Two dimensional echocardiography (Vivid 7, GE Vingmed, Horten, Norway) was performed to all studied children to evaluate presence of EAT and LVH. Epicardial fat thickness was measured on the free wall of the right ventricle from parasternal long axis view while the patient is lying supine and breathing gently. Epicardial adipose tissue is usually seen as an echo-free or if it is massive, hyper-echoic space. Three measurements were taken and averaged to demonstrate epicardial fat thickness (normal >1mm). Echocardiography was used to assess the left ventricular hypertrophy when the left myocardial wall is more than 0.78 cm thick.