Epicardial fat volume linked with progression of atherosclerosis
MedWire News: Increases in epicardial fat volume are associated with progression of coronary artery calcification in intermediate-risk patients, research shows.
Patients with the most coronary calcification exhibited the largest increases in epicardial fat volume when compared with age- and gender-matched controls with low coronary artery calcification.
"A potential explanation for this finding is that epicardial fat may be atherogenic due to its inflammatory activity," say Daniel Berman (Cedars-Sinai Medical Center, Los Angeles, California, USA) and colleagues in the journal Atherosclerosis.
Defined as the volume of adipose tissue surrounding the heart, epicardial fat is constrained by the pericardium.
Previous studies have suggested that it might be an important marker of coronary artery disease, while other studies have shown that epicardial fat volume is associated with the presence and severity of coronary calcification, myocardial ischemia, and adverse cardiovascular outcomes.
It is not known, however, whether changes in the epicardial fat volume are related to changes in coronary calcification.
In the current study, the researchers identified 375 consecutive patients with an intermediate risk of coronary disease who underwent serial computed tomography (CT) at least 3-5 years apart.
Individuals were divided into different tertiles based on the progression of calcification over time. Patients defined as 'high progressors' were matched by age and gender to those from the lower tertile.
At baseline, there was no difference in epicardial fat volume and epicardial fat volume indexed to body surface area.
At follow-up, epicardial fat volume in the high progressors increased significantly when compared with individuals with the lowest progression of coronary artery calcification.
Among those with the most calcification, epicardial fat volume was 102 cm3, significantly higher than the 90 cm3 observed among those with less progression of calcification (p=0.03).
Using fat volume indexed to body surface area, the difference between high and low progressors remained statistically significant (50 cm3/m2 vs 46 cm3/m2; p=0.03).
After adjusting for multiple variables, individuals with increases in epicardial fat volume indexed to body surface area ≥15% were more than two times more likely to have a larger progression of coronary calcification than those with less progression (odds ratio 2.3; p<0.05).
Similarly, those with fat volume increases ≥15%, as well as those with hypertension, were more likely to have new calcified plaques on follow-up (p=0.02).
In addition to inflammatory activity as a potential cause of the increased calcification, Berman and colleagues note there are differences in adipokine expression in epicardial adipose tissue, with protective factors such as adiponectin attenuated in patients with coronary artery disease.
However, they do not rule out that the changes in epicardial fat volume and coronary calcification might be related to unmeasured confounding variables, such as diet or exercise, or even medical therapy received between visits.
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