Objective To evaluate the diagnostic accuracy of 320-detector row CT coronary angiography(CTCA)in detecting preoperative coronary artery disease (CAD) in patients with atrial fibrillation (AF) and rheumatic left artrioventricular valve disease (RMVD), so as to assess its feasibility in screening CAD before operation for RMVD. Methods Thirty-five RMVD patients with persistent CAD were enrolled in the present study. All the patients underwent both CTCA and conventional coronary angiography (CCA) before operation. The relationship between mean heart rate and CT image quality was evaluated by Pearson’s correlation coefficient. The sensitivity, specificity, positive predictive value(PPV) and negative predictive value (NPV) of CTCA in diagnosis of stenosis (≥50%) were calculated using the conventional coronary angiography as the reference. Kappa statistics was used to assess the agreement between 320-detector CTCA and CCA in detecting CAD. Results The mean heart rate was 94.7±21.4 beats/min in the 35 patients. There was a significant correlation between the mean heart rate and image quality, especially for middle segment of right coronary artery(r=0.554,P=0.002) and middle segment of the circumflex artery (r=0.559,P=0.016). The sensitivity, specificity, PPV and NPV of CTCA in diagnosing CAD were 87.5%, 99.4%, 82.4% and 99.6% in segment-based analysis, 87.5%, 97.6%, 82.4% and 98.4% in vessel-based analysis, and 84.6%, 86.3%,78.6% and 90.5% in patient-based analysis, respectively. The kappa statistics were 0.843, 0.828 and 0.699, respectively. ConclusionCTCA has a high accuracy in diagnosing CAD, and it can be used for preoperation screening of patients with AF and RMVD.