Increased Epicardial Fat Tissue is Predictor for Patients with Ischemia and No Obstructive Coronary Artery Disease

Background: Epicardial adipose tissue (EAT) may play a vital role in the progression of ischemia and no obstructive coronary artery disease (INOCA). CT can achieve a precise quantification of EAT for its higher spatial resolution compared to other methods. Objectives: This study aimed at exploring EAT in patients with INOCA, and its associations with other clinical factors. Methods: From January 2017 to October 2018, a total of 254 consecutive patients suspected with coronary atherosclerotic disease (CAD) underwent cardiac computed tomography angiography (CCTA). There were 195 patients who were excluded for obstructive CAD by CCTA analysis and CT derived fractional flow reserve (CT-FFR) (≤ 0.80). Seventy-two patients with either angina and/or signs of ischemia but without obstructive CAD were recruited as INOCA group. Forty-eight controls without angina and risk factors for INOCA were enrolled as the control group. EAT volume and thickness, and other factors were analyzed in INOCA and control groups. Results: Despite similar body mass index (BMI), EAT thickness and volume were significantly elevated in INOCA patients compared with the control group (P < 0.001). Receiver operating characteristic curve analysis for identifying INOCA exhibited a higher area under the curve of EAT volume (0.773, 95%CI 0.616-0.930) than EAT thickness (0.692, 95%CI 0.597-0.786). The cut-off values for EAT thickness and volume were 3.2 mm and 179.6 cm3, respectively. Presence of hypertension, triglyceride levels, and EAT thickness and volume were significantly associated with INOCA and lowly affected by other factors in multiple logistic regression analysis. Conclusions: INOCA patients have more EAT compared with controls. EAT is a marker of INOCA and may be a predictor of pharmacological therapy and a prognostic indicator. Further research should focus on the myocardial microcirculation changes by EAT volume reduction.