Relationship Between Epicardial Fat Volume and Coronary Microvascular Dysfunction in Patients with Chest Pain and Unobstructed Coronary Arteries

Objective Epicardial fat (EF) is metabolically active adipose tissue positioned between the epicardial surface of the heart and the pericardium. We investigated whether there is a relationship between EF and Coronary Microvascular Dysfunction (CMD) in patients presenting with chest pain and unobstructed coronary arteries. Materials and Methods This study recruited patients referred to cardiology clinics for assessment of chest pain who subsequently underwent assessment via CT coronary angiogram (CTA). Myocardial blood flow reserve (MBFR) was assessed using myocardial contrast echocardiography. Epicardial fat volume (EFV) was measured by tracing serial slices on CTA with corresponding Hounsfield units of −195 to −45. Results We recruited 134 participants with a mean age of 59.2 (9.8) years. CMD was present in 54 (40%) patients, and the measured mean EFV was 128 mm3 (96, 168). Fortythree patients (32%) had a coronary artery calcium score (CACS) of 0, 64 (48%) had a CACS of 1–100, 18 (13%) had a CACS of 101–400, and 9 (7%) had a CACS >400. Univariate regression analysis showed that EFV and MBFR had a correlation coefficient of R=−0.22, with a significant regression slope (β=−0.002, p=0.012). Multivariable linear regression analysis using MBFR as a continuous outcome variable revealed age (β=−0.012, p=0.011) and CACS (β=−0.003, p=0.023) to be associated with MBFR. EFV was not associated with MBFR (β=−0.0007, p=0.538). Model repetition with MBFR as a dichotomous variable (MBFR ≥2 or