Persistent epicardial adipose tissue accumulation is associated with coronary plaque vulnerability and future acute coronary syndrome in non-obese subjects with coronary artery disease.

Objective. Epicardial adipose tissue (EAT) is recognized as a novel risk factor for coronary artery disease (CAD), and its contribution is thought to be stronger in non-obese patients than in obese patients. However, the prognostic impact of the progression of EAT accumulation after comprehensive management for atherosclerotic risk factors remains unclear. This study aimed to investigate whether an increase of the EAT volume during follow-up predicts future acute coronary syndrome (ACS) events in non-obese CAD patients. Methods. This study consisted of 517 non-obese CAD patients (368 men; age, 66 ± 10 years) who underwent serial multidetector computed tomography (MDCT) examinations to evaluate coronary atherosclerosis progression. The MDCT examination was used to assess the severity of stenosis, plaque characteristics, and EAT volume. All patients received comprehensive management to reduce CAD risk factors after the first MDCT examination. The MDCT examination was repeated at 6-24 months, and patients were followed-up for more than 1 year or until the occurrence of ACS events. Results. Of 517 patients, 159 (31%) patients were classified into increase of EAT volume during follow-up, 91 (18%) into decrease of EAT volume during follow-up, and 267 (51%) patients into constant of EAT volume during follow-up. The prevalence of obstructive plaques and MDCT-derived vulnerable features of coronary plaques were significantly elevated in patients with increase of EAT volume during follow-up. In contrast, no significant changes were observed in the other 2 groups. During the follow-up period of 4.1 ± 1.8 years (median 4.4 years) after the second MDCT examination, ACS occurred in 43 (8.3%) patients. Multivariate Cox regression analysis showed that the presence of low-attenuation plaque (hazard ratio [HR]; 1.78, p = 0.04) and napkin-ring sign (HR; 3.74, p < 0.001) at second MDCT examination, and changes of EAT volume per 10 ml (HR; 1.34, p = 0.004) were associated with future ACS events. Conclusion. Patients with increase of EAT volume during follow-up despite comprehensive management for CAD risks had an increased prevalence of obstructive plaques and plaques with high-risk features, which could be associated with unfavorable ACS outcomes in non-obese CAD patients.