Abstract 132: Epicardial, Pericardial and Periaortic Fat Are Elevated in Older Adults at High Cardiac Risk

Abstract

Background: Excess fat around the heart and aorta may be novel risk factors for heart failure, independent of total adiposity. However, the mechanisms underlying this association are unknown. Purpose: To measure epicardial fat (EAT, within the pericardium), paracardial fat (PAT, outside the pericardium), and periaortic fat around the ascending and descending aorta in older adults to test the hypothesis that visceral adiposity is positively associated with arterial stiffness. Methods: Fat volumes were measured by MRI in 40 high-risk adults (age: 69±9 yrs, 50% female) with hypertension (96%), diabetes (35%), or coronary artery disease (35%) and 20 age- and gender-matched controls. High-risk adults were further characterized as very stiff or moderately stiff based on pulse wave velocity values above or below the median (850 cm/s). EAT and PAT were measured from the base to the apex of the heart. Periaortic fat was measured at the level of the main pulmonary artery. Results: After adjusting for BMI, both high-risk groups had greater periaortic fat compared to controls (p<0.01, Figure); however, only adults with very stiff aortas had greater EAT and PAT than controls (p<0.02). Despite 12-25% higher EAT and PAT in very stiff vs. moderately stiff adults, fat volume differences did not reach statistical significance between these groups. Total arterial compliance (defined as the ratio of left ventricular stroke volume to brachial artery pulse pressure) was weakly correlated with periaortic fat around the descending aorta in controls (r=-0.39, p=0.09), but not in the high-risk group. Conclusions: Older adults at high cardiac risk have greater EAT, PAT, and periaortic fat compared to low-risk controls. However, greater visceral adiposity is not strongly associated with worse arterial stiffness in this population.