PurposeMitral valve surgery in children involves correcting congenital and acquired pathologies, with a reported mortality rate of 0.9%. Low cardiac output syndrome (LCOS) is a serious complication with the incidence of 20–25%. The aim of the study was to estimate possible prognostic factors of LCOS in children undergoing mitral valve procedure. Material and methodThis single-center retrospective analysis enrolled children aged <18 years who underwent mitral valve surgery during 24 year period. Preoperative clinical and laboratory parameters, and operative factors were analyzed. ResultsThirty consecutive pediatric patients (11 (37%) males and 19 (63%) females) in median (Q1 – Q3) age of 57 (25–115) months, who underwent mitral valve replacement, were included. The 30-day mortality was 7% (2 patients) and was related to postoperative multiorgan failure. LCOS occurred in 8 (27%) children. The receiver operator curve (ROC) analysis established parameters that have predictive value for LCOS occurrence: cardiopulmonary bypass (CPB) time, with 89 min as optimal cut-off point (AUC = 0.744, p = 0.011) yielding sensitivity of 100% and specificity of 42.9%; left ventricular ejection fraction (LVEF) < 60 % (AUC = 0.824, okp = 0.001) with sensitivity of 62.5% and specificity of 93.75%; and red blood cell distribution width (RDW) above 14.5 % (AUC = 0.840, p < 0.001; sensitivity of 87.5% and specificity of 75%). ConclusionsIn mitral valve replacement in pediatric patients, CPBtime above 89 min, preoperative LVEF below 60% and preoperative RDW above 14.5% can be regarded as the potential predictors of LCOS.