SummaryAs for nonvalvular atrial fibrillation (NVAF) patients with left atrial thrombus or spontaneous echo contrast (LAT/SEC), we evaluated the additional predictive value of serum uric acid (SUA) and Left atrial diameter (LAD) for CHADS2 and CHA2DS2-VASc, and explored the influence from the level of SUA and LAD to LAT/ SEC in moderate risk group. Thus, we put forward the concept of a borderline high risk group to guide clinical anticoagulant therapy in patients with NVAF.A total of 284 NVAF patients without the history of anticoagulant prior to hospitalization were enrolled. They were divided into LAT/SEC group or No LAT/SEC group according to transesophageal echocardiography (TEE). Then, we explored and compared the additional predictive value of serological and ultrasonic indexes after combining them to CHADS2/CHA2DS2-VASc.61 patients (21.48%) had LAT/SEC. SUA and LAD were the independent risk factors of LAT/SEC. After being added with LAD and SUA, the predictive value of CHADS2 and CHA2DS2-VASc were increased much more than others. In the moderate risk group, the incidence of LAT/SEC rose significantly when SUA or LAD was higher than cut-off values.SUA and LAD enhanced the predictive ability of CHADS2 and CHA2DS2-VASc for LAT/SEC as additional factors. For patients in moderate risk group, if SUA or LAD was higher than cut-off values, the risk of thromboembolism events would rise accompanied by the elevated risk of LAT/SEC.(Int Heart J 2017; 58: 885-893) Key words: Predictive value, Left atrial thrombus, Borderline high risk group A trial fibrillation (AF) is the most common arrhythmia, affecting approximately 8 million patients in China.1) Meanwhile, its morbidity is increasing with the aging population as well as the morbidity of cardiovascular disease year by year. Cardiac stroke accounted for about a quarter of all patients with stroke, and more than half of them were caused by AF.2) AF increased the risk of stroke by five times. Among them, more than 90% of embolism comes from left atrial appendage (LAA). Therefore, preventing thrombus in LAA can reduce the morbidity of stroke, and it can be used as a substitute to prevent patients with AF from stroke in earlier stage.At present, CHADS2 scores and CHA2DS2-VASc scores are widely accepted and practical clinical stroke risk stratifications. Recently, some researches have shown that CHADS2 and CHA2DS2-VASc scores not only predict stroke risk, but also have an obvious relationship with LAT and can be used to predict the formation of LAT. [3][4][5][6] However, Yarmohammadi, et al. 4) found that patients with a score of 0 or 1 point in CHADS2 accounted for almost a third of the total with atrial thrombus. In addition, a prospective study including 295 NVAF patients with 0 or 1 point CHADS2 score were followed up, onaverage for 5 years. The results showed that 3% of the patients had LAT and 8% of patients had SEC. 7) By adding some additional risk factors to CHADS2 and CHA2DS2-VASc score, especially in patients who should have anticoagulant therapy but were i...