Abstract: AIM:To investigate the clinical significance and changes of brain natriuretic peptide (BNP), NT-proBNP and NT-proBNP/BNP during the perioperative period in patients with mitral valve replacement. METHODS: The study enrolled 25 patients with mitral valve stenosis (MS) and 20 patients with mitral valve regurgitation (MR). The concentrations of plasma BNP NT-proBNP and NT-proBNP/BNP were measured 1 day prior to cardiac surgery and during the first, second, third and fourth weeks after cardiac surgery. At the same time, left ventricular ejection fraction (LVEF), left atrial diameter (LAD), and left ventricular end-diastolic diameter (LVEDD) were measured by echocardiogram. The changes of observation indicators during the perioperative period were analyzed. RESULTS: Before surgery, BNP and NT-proBNP were correlated positively with NYHA and LVEDD (P<0.05) but not correlated with LVEF and LAD. BNP correlated more with NYHA and LVEDD than with NT-proBNP and NT-proBNP/BNP. Before surgery, levels of BNP and NT-proBNP in patients with atial fibrillation (AF) after surgery was higher than those in patients without AF and decreased with AF converting to normal. The changes of the levels of NT-proBNP in patients with renal dysfunction after surgery were similar to those in patients with atial fibrillation, but no such difference was observed in NT-proBNP/BNP. Before surgery, LVEDD, BNP and NT-proBNP in the MR group were higher than those in the MS group but, with the changes of LVEDD, the difference in BNP and NT-proBNP became insignificant between groups. No difference was observed in NT-proBNP/BNP between groups before surgery. BNP and NT-proBNP in patients with mitral valve replacement increased in the early perioperative period and decreased in the late phase. The main changes of BNP, NT-proBNP and LVED occurred during the first 3 weeks after operation and no obvious relationship was found between the changes of NT-proBNP/BNP and the changes of BNP, NT-proBNP and LVEDD. CONCLUSION: The level of BNP can reflect the changes of LVEDD and can be used as a reference index for cardiac function before surgery, but NT-proBNP/BNP is of no great clinical value. The differences of BNP and NT-proBNP between the MR group and MS group may mainly relate to the size of the LVEDD. Monitoring BNP, NT-proBNP and LVEDD in patients with mitral valve replacement has some positive clinical significance perioperatively.