Epicardial fat is associated with adverse ventricular remodeling and diastolic dysfunction in women with ischemia but no obstructive coronary artery disease

Abstract Background Epicardial fat is a metabolically active adipose tissue depot located between the myocardium and visceral pericardium. Increased epicardial fat is associated with the development of atherosclerosis and obstructive coronary artery disease (CAD). However, information regarding relations between epicardial fat—which covers 80% of the heart surface—and cardiac function, is limited. Purpose To evaluate relations between epicardial fat and cardiac morphology and function in all four chambers of the heart. Methods To accomplish our objective, we studied 113 participants from the Women’s Ischemia Syndrome Evaluation cohort who underwent invasive measurement of left ventricular end-diastolic pressure and coronary reactivity, and comprehensive rest-stress cardiac magnetic resonance imaging (cMRI) per standardized protocols. Epicardial fat area was measured from a single high resolution steady-state free precession cine cMRI in the horizontal long axis plane (Figure 1A). Left ventricular (LV) mass, bi-ventricular volumes, and ejection fractions, were assessed using a stack of short axis cine images covering both ventricles (Figure 1B). LV concentricity was defined as the mass-to-end-diastolic volume ratio. Strain and strain rate were assessed in all four chambers by feature tracking (Figure 1C). Left atrial (LA) volume was assessed using three orthogonal long-axis cines, while right atrial (RA) area was assessed using a single horizontal long axis cine (Figure 1D). Participants were stratified by the median epicardial fat area, defined as "Low" epicardial fat (<13 cm2, n=48) and "High" epicardial fat (≥13 cm2, n=65). Results Participant characteristics are reported in Table 1. Notably, the majority (58%) had "High" epicardial fat and body mass index (BMI) was greater in the "High" epicardial fat group. After adjusting for BMI, however, bi-ventricular stroke index remained lower in the "High" epicardial fat group, as did bi-atrial ejection fraction (fractional area change, RA). Moreover, compared to the "Low" epicardial fat group, LV concentricity and LA booster strain were higher in the "High" epicardial fat group (Figure E-F), while LV longitudinal strain and LV early circumferential diastolic strain rate were lower (Figure G-H). No other major differences were observed between groups, including coronary reactivity or myocardial perfusion reserve. Conclusions Together, these data suggest that higher BMI is associated with increased epicardial fat that is related to adverse cardiac remodeling, along with systolic and diastolic dysfunction, across multiple cardiac chambers. Further studies would be useful to define specific mechanism contributing to these observations.Figure 1Table 1