Objective: There is no clear consensus regarding the definition of low cardiac output syndrome (LCOS) or the follow-up of this patient group. Given this lack of a clinical definition, the aim of this study was to use a LCOS score (LCOSs) similar to the low cardiac output score previously presented in the literature and evaluate the relationship between a high LCOSs and poor clinical outcome. Methods: A total of 54 patients were prospectively evaluated after cardiac surgery. The LCOSs was used to evaluate the development of low cardiac output. Each parameter was scored as 1 point. The score was calculated every hour for 24 hours postoperatively and the highest score was recorded as the peak score (pLOCSs). The LOCSs at the time of admission to the pediatric intensive care unit, at the 4th, 8th, and 16th hour were recorded and a cumulative score (cLOCSs) score was calculated. Results: The mean age of the patients was 49.40 +/- 53.15 months and 24.07% had LOGS. In the group with LCOS, the cLOCSs, vasoactive-inotropic score (VIS), lactate mean, aortic clamp time, and the total cardiopulmonary bypass time were significantly higher. In this study, a significant and positive correlation was found between the cLOCSs and pLOCSs and the length of hospital stay, length of stay in the pediatric intensive care unit, VIS, lactate mean, and aortic clamp duration. Conclusion: The objective of this study was to draw attention to the potential use of a common language in the care of critical pediatric patients undergoing cardiac surgery with a previously defined scoring method that includes parameters indicating poor perfusion in the patient.