Associations of pericardial and intra-thoracic fat with coronary calcium presence and progression in a multi-ethnic study

OBJECTIVE Body mass index (BMI) may not accurately or adequately reflect body composition or its role in the development of cardiovascular disease (CVD). Ectopic adipose depots may provide a more refined representation of the role of adiposity in CVD. Thus, the association of pericardial and intra-thoracic fat with coronary artery calcium (CAC) was examined. DESIGN AND METHODS Nearly 600 white men and women, as well as Filipina women and African-American women, all without known CVD, had abdominal and chest computed tomography (CT) scans at two time points about 4 years apart from which CAC presence, severity and progression, as well as pericardial and intrathoracic fat volumes were obtained. Logistic and linear regression models with staged adjustment were used to assess associations of pericardial and intra-thoracic fat with CAC presence, severity, and progression. RESULTS After adjustment for age, BMI, sex/ethnic group, ever smoking, and lipids, each standard deviation higher increment of intra-thoracic fat, but not pericardial fat, was significantly associated with 3.84-fold higher odds of prevalent CAC (95% CI (1.54, 9.58), P = 0.004) and a 38.4% higher CAC score (95% CI (3.5%, 90.0%), P = 0.03). Neither pericardial nor intrathoracic fat were associated with CAC progression. CONCLUSIONS Contrary to previous reports, pericardial fat was not associated with the presence, severity or progression of CAC. However, a significant association between intrathoracic fat and both the presence and severity of CAC was demonstrated. Studies measuring fat in the thoracic cavity may consider defining intrathoracic fat as a separate entity from pericardial fat.