Abstract: ObjectiveTo explore the value of cystatin C in prediction of severe coronary artery disease and its clinical application in patients with acute ST elevation myocardial infarction (STEMI). MethodsA total of 321 patients with STEMI were divided into three groups according to levels of cystatin C. The   study included clinical data， laboratory examination indicators， the results of coronary angiography and adverse events during hospitalization. The relationship between cystatin C and Gensini score， Syntax score and other indicators were analyzed. At the same time， the patients were divided into mild to moderate stenosis group and severe disease group according to Gensini score. Logistic regression analysis model， ROC curve analysis of cystatin C and STEMI risk factors on the severity of coronary artery disease were analyzed. ResultsThe Gensini score of high level of cystatin C group (Group C3) was significantly increased than that of the other two groups (P<0.01). Cystatin C was positively associated with a higher Gensini and Syntax scores (r=0.256; 0.353，P<0.01). In addition， the value of Cystatin C on predicting the severe STEMI vascular lesions was equal to troponin. ConclusionSerum cystatin C level significantly increased in STEMI patients and it has positively relationship and good predictive value with the severity of coronary artery lesions.

Key words: myocardial infarction, cystatin C, gensini score, syntax score