Introduction: EAT is an independent factor in coronary artery disease (CAD). The objectiveof the current study was to define an echocardiographic cut-off point for EAT and to determine its diagnostic value in predicting the increase in CAD risk.Methods: Two hundred patients underwent coronary artery angiography for diagnosis of CAD and transthoracic echocardiography for measurement of EAT on the right ventricle (RV), RV apex and RV outlet tract. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the EAT cut-off points in the three above-mentioned areas for predicting the severity of CAD were measured. The relation between the EAT and CAD risk factors was evaluated as well.Results: EAT was independent from gender, height, hypertension, diabetes, HDL, total cholesterol, ejection fraction, acute coronary syndrome, and the location of the coronary artery stenosis in the coronary artery in all three anatomical areas. EAT on RV and RV apex had a significant relation with CAD (P£0.05). Overall, RV EAT³10 mm and RV apex EAT³8 mm had sensitivity and PPV of more than 70% in predicting coronary stenosis ³50% and acute coronary syndrome (ACS) and RVOT EAT ³13 mm is of PPV=83.5% for predicting coronary stenosis ³50%.Conclusion: EAT thickness has an acceptable diagnostic value for predicting severe coronary artery stenosis and ACS. Therefore, non-invasive EAT thickness measurement could be of great assistance to clinicians for detecting the patients at risk and helping them to undergo supplementary evaluations with invasive approaches.