Aims: Our study aimed to investigate the effect of activated clotting time (ACT) and hematocrit (HCT) levels on commonly used hematological and coagulation parameters (RDW, PLT, MPW, PT, INR, APTT, CRP) in patients undergoing cardiopulmonary bypass (CPB), and to determine the predictive power of these parameters for ACT.Methods: Pre-and postoperative hematological and coagulation data of patients who underwent open-heart surgery with CPB between January 2024 and June 2025 were retrospectively analyzed. Patients were grouped according to ACT and HCT levels. Intergroup differences were assessed using appropriate parametric or non-parametric tests. Receiver operating characteristic (ROC) analysis and logistic regression were performed to evaluate the predictive value of ACT.Results: No significant differences were observed in most hematological and coagulation parameters according to ACT and HCT levels (p0.05). Only PRE.RDW and POST.PLT were significantly different according to HCT levels, and only POST.CRP was significant according to ACT levels (p
ERSÖZ et al. (Tue,) studied this question.