Quantification of epicardial and intrathoracic fat volume does not provide an added prognostic value as an adjunct to coronary artery calcium score and myocardial perfusion single-photon emission computed tomography.

Abstract

To compare the predictive value of epicardial and intrathoracic fat volume (EFV, IFV), coronary artery calcium (CAC) score, and single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for major adverse cardiac events (MACE). Follow-up was obtained in 275 patients with known or suspected coronary artery disease (CAD), who underwent SPECT-MPI including non-contrast cardiac computed tomography (CT) for attenuation correction to evaluate ischaemic heart disease and in whom EFV, IFV, and CAC score were calculated from non-contrast CT. Associations between fat volume, traditional cardiovascular risk factors, CAC score, and SPECT-MPI results were assessed and MACE predictors identified by Cox proportional hazard regression and global χ(2) statistics. After a median follow-up of 2.9 years, MACE were recorded in 38 patients. In univariate Cox regression analysis, EFV and IFV were predictors of MACE (P = 0.013 and P = 0.004, respectively). In multivariate analysis, EFV and IFV provided incremental predictive value beyond traditional cardiovascular risk factors (P < 0.05 and P < 0.01). However, after adjustment for CAC score and SPECT-MPI results, EFV and IFV fell short of statistical significance as independent outcome predictors. Quantification of EFV and IFV is associated with MACE and may improve risk stratification beyond traditional cardiovascular risk factors. However, once CAC score and/or SPECT-MPI results are known, EFV and IFV do not provide any added clinically relevant prognostic value. Further studies may identify the subpopulation with the largest relative merit of EFV and IFV as an adjunct to SPECT-MPI and CAC score.