Abstract: Objective To explore the value of spiral CT coronary angiography (CTA) in evaluation of morphological and functional parameters of the left atrial appendage (LAA) and the diagnosis of thrombosis in patients with atrial fibrillation (AF) before operation. 
Methods A total of 98 patients undergoing radiofrequency ablation in Hebei Petro China Central Hospital were selected as the AF group, and 45 volunteers with sinus rhythm who underwent CTA examination during the same period were selected as the control group. The quantitative CTA parameters and morphological characteristics of LAA in the two groups were compared, and whether the patients had LAA thrombosis was determined based on the results seen during the operation. The value of CTA in the diagnosis of LAA thrombosis was calculated. 
Results The measured values of main lobe length of LAA, LAA opening area (LAAOA), the maximum diameter of LAA, the minimum diameter of LAA, LAA volume and left atrial volume in AF group were greater than those in control group (P＜0.05). The measured values of LAA emptying velocity (LAAEV) and LAA filling velocity (LAAFV) in patients with AF were lower than those in the control group (P＜0.05). The proportion of cauliflower-shaped LAA in the AF group was higher than that in the control group (P＜0.05), while the proportion of chicken wing-type LAA in AF group was smaller than that in control group (P＜0.05). The measured value of the length of the main lobe of LAA, the maximum diameter of LAA, LAAOA, and LAA volume in the thrombosis group were greater than those in the non-thrombosis group (P＜0.05), while the measured values of LAAEV and LAAFV in thrombosis group were lower than those in non-thrombosis group (P＜0.05). The proportion of cauliflower-shaped LAA in thrombosis group was higher than that in non-thrombosis group (P＜0.05), while the proportion of the chicken wing-type LAA in thrombosis group was smaller than that in non-thrombosis group (P＜0.05). CTA diagnosis showed that the sensitivity of LAA thrombosis in patients with AF was 62.96%, the specificity was 92.96%, and the missed diagnosis rate and misdiagnosis rate were 37.04% and 7.04% respectively. 
Conclusion The CTA parameters and morphology of the LAA of patients with AF have significantly changed compared with those with sinus rhythm. In the meantime, CTA has a higher specificity for the diagnosis of thrombosis in the LAA of patients with AF, and can be used as an effective method for clinical auxiliary diagnosis.

Key words: atrial fibrillation, atrial appendage, coronary angiography