Lack of association between epicardial fat volume and extent of coronary artery calcification, severity of coronary artery disease, or presence of myocardial perfusion abnormalities in a diverse, symptomatic patient population: results from the CORE320 multicenter study

Abstract

Background: Epicardial fat may play a role in the pathogenesis of coronary artery disease (CAD). We explored the relationship of epicardial fat volume (EFV) with the presence and severity of CAD or myocardial perfusion abnormalities in a diverse, symptomatic patient population.

Methods and results: Patients (n=380) with known or suspected CAD who underwent 320-detector row computed tomographic angiography, nuclear stress perfusion imaging, and clinically driven invasive coronary angiography for the CORE320 international study were included. EFV was defined as adipose tissue within the pericardial borders as assessed by computed tomography using semiautomatic software. We used linear and logistic regression models to assess the relationship of EFV with coronary calcium score, stenosis severity by quantitative coronary angiography, and myocardial perfusion abnormalities by single photon emission computed tomography (SPECT). Median EFV among patients (median age, 62.6 years) was 102 cm(3) (interquartile range: 53). A coronary calcium score of ≥1 was present in 83% of patients. Fifty-nine percent of patients had ≥1 coronary artery stenosis of ≥50% by quantitative coronary angiography, and 49% had abnormal myocardial perfusion results by SPECT. There were no significant associations between EFV and coronary artery calcium scanning, presence severity of ≥50% stenosis by quantitative coronary angiography, or abnormal myocardial perfusion by SPECT.

Conclusions: In a diverse population of symptomatic patients referred for invasive coronary angiography, we did not find associations of EFV with the presence and severity of CAD or with myocardial perfusion abnormalities. The clinical significance of quantifying EFV remains uncertain but may relate to the pathophysiology of acute coronary events rather than the presence of atherosclerotic disease.

Keywords: coronary artery disease; coronary stenosis; myocardial ischemia.

Figure 1. Epicardial Fat Volume Quantification

The figure illustrates our method of epicardial fat volume quantification using a semi-automated software. After manually tracing the pericardial borders, fat volume is derived based on Hounsfield unit attenuation within the region of interest. Left: The white arrows point to the pericardial sac as a thin band enveloping the heart. Middle: The pericardial sac is traced by an expert observer. Right: The overlay represents epicardial fat enclosed by the pericardium.

Figure 2. Distribution of Epicardial Fat Volume in the Study Population

The percentile box plot shows the distribution of epicardial fat volume among the 380 study participants.

Figure 3. Relationship between Epicardial Fat Volume and Coronary Calcium Score

Shown is a scatterplot and Lowess smoothing of epicardial fat volume (EFV) and coronary artery calcium score (CACS) revealing no significant association.

Figure 4. Relationship between Epicardial Fat Volume and Coronary Artery Stenoses

Shown is a scatterplot and Lowess smoothing of epicardial fat volume (EFV) and presence of a ≥50% stenosis by quantitative coronary angiography (QCA) stenosis revealing no significant association. Please note clustering of data points at the extreme ranges due to imputation of values less than 30% and at 100%.

Figure 5. Relationship between Epicardial Fat Volume and Myocardial Perfusion Abnormalities

Shown is a scatterplot and Lowess smoothing of epicardial fat volume (EFV) and presence of myocardial perfusion abnormalities using summed stress score (SSS) by SPECT revealing no significant association.