Echocardiography and dual-energy x-ray absorptiometry in the elderly patients with metabolic syndrome: a comparison of two different tecniques to evaluate visceral fat distribution

Abstract

Objectives: Metabolic syndrome (MetS) is an important risk factor for vascular diseases. Two simple and low cost measurements, the epicardial fat (EFT) obtained by echocardiography and abdominal fat (AFT) thickness evaluated by Dual-Energy X-Ray Absorptiometry (DEXA), have been validated as a markers of fat storage in young adults and elderly patients affected by MetS. At present no studies are available yet to compare the two techniques and to test their relationship with MetS. Moreover, no data exit concerning the association between hepatic steatosis, a well known indicator of intra hepatic fat storage and perivisceral fat storage. Aims of our study were: 1) to compare EFT and AFT in a group of patients with and without MetS; 2) to study whether and how these two different approaches predict MetS or risk of malnutrition in the obese elderly; 3) to evaluate the relationship between MetS occurrence, EFT, AFT and hepatic steatosis (HS).

Setting and participants: We studied 55 elderly outpatients ( 29 males and 26 females) referred to MetS service of the IRCCS "Casa Sollievo della Sofferenza" during the year 2007.

Measurements: Subjects underwent a complete clinical and anthropometric evaluation, laboratory tests for glycaemia and lipid profile for MetS definition. Liver ultrasound was executed to verify the occurrence of HS, a well known indicator of intraparenchymal fat storage. HS was defined as hyperechoic liver pattern in patients without liver disease or hepatic enzymes abnormalities. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Echocardiography for EFT evaluation and DEXA for AFT and fat free mass of the abdomen (FFM) measurement were also performed. Mini Nutritional Assessment (MNA) was used to test the risk of malnutrition in the elderly.

Results: Patients were divided in two groups according to the absence (24 patients Group 1) or the presence (31 patients Group 2) of the MetS. HS was present in 26 (57.7%) patients. MetS patients had significantly higher AFT and EFT, and lower FFM than patients without MetS. MNA scores were not different. EFT and AFT showed a good correlation ( R 0.8 p < 0.001) but only EFT was associated with the MetS. HS was also correlated to EFT and AFT. MNA showed a risk of malnutrition in 73% of MetS patients and 23% in patients without MetS but both EFT and AFT were not correlated with MNA scores.

Conclusions: In the elderly patient with MetS, AFT and EFT are greater than in non MetS patients. Both AFT and EFT are strongly correlated to HS but only EFT was associated with MetS. In obese patients, the risk of malnutrition, as evaluated by MNA, is not associated with an increased fat tissue measured by echocardiography or DEXA.