The relationship between epicardial fat volume and incident coronary artery calcium.

BACKGROUND: Epicardial fat volume (EFV) has been associated with prevalent but not incident coronary artery calcium. However, the relationship between EFV and development of incident coronary calcium (incCC) has not been reported.

OBJECTIVE: We evaluated the relationship between epicardial fat volume and the development of coronary artery calcium over 3-5 years.

METHODS: From 1248 subjects who underwent 2 serial noncontrast cardiac CT scans 3-5 years (median, 4 years) apart to measure coronary calcium score of 0 who subsequently developed incident coronary calcium (incCC(+)) were matched to 106 controls in whom coronary calcium score remained 0 (incCC(-)). EFV was calculated by determination of the pericardial contour, followed by identification of fat voxels with the use of validated software (QFAT). Baseline EFV and EFV indexed to body surface area (EFVi) and subsequent EFV and EFVi changes were compared between incCC(-) and incCC(+) populations. A significant EFV increase was defined as a ≥10% and ≥25% increase from the baseline value.

RESULTS: Baseline EFVi was similar between the 2 groups [EFVi, 40.9 ± 17.9 cm³ (median, 38.3 cm³) in incCC(-) vs 40.3 ± 16.3 cm³ (median, 37.0 cm³) in incCC(+); P = 0.96]. On the follow-up CT, EFVi increased in 74.5% of incCC(-) and in 76.4% of incCC(+) (P = 0.75). EFVi changes between the 2 groups were similar [4.9 ± 8.9 cm³ (median, 4.9 cm³) in incCC(-) vs 4.2 ± 8.0 cm³) (median, 3.5 cm³) in incCC(+); P = 0.67]. On multivariate analysis, after adjusting for cardiovascular risk factors, incCC was not related to an increase in EFVi at a 10% or 25% level.

CONCLUSIONS: In very low-risk subjects with a coronary calcium score of 0, baseline EFVi and change in EFVi after 3-5 years were not related to the development of incidental coronary artery calcium.