Objective To analyze the clinical characteristics of in-hospital cardiac arrest(IHCA)patients undergoing ex-tracorporeal cardiopulmonary resuscitation(ECPR)and explore the main risk factors leading to in-hospital mortality.Methods A retrospective analysis was conducted on the clinical data of 115 IHCA patients who received ECPR at the First Affiliated Hospital of Zhengzhou University from January 2020 to December 2022.Patients were divided into a survival discharge group and an in-hospital mortality group based on clinical outcomes.The differences in clinical data between the two groups were compared,and relevant risk factors for in-hospital mortality and poor prognosis were investigated.Cox multivariate regression analysis was used to explore the impact of various variables on in-hospital mortality.Results This study retrospectively ana-lyzed 115 ECPR patients over the past three years,ultimately including 74 patients based on inclusion and exclusion criteria,with a survival discharge rate of 36.5%.Compared to the survival discharge group,the in-hospital mortality group had shorter ECMO run time and hospital stay,higher lactate levels at 24 hours post-ECMO stabilization,lower 24-hour lactate clearance rate,more CRRT treatments,more limb and cardiac complications,less return of spontaneous circulation before ECPR,higher SOFA and APACHE II scores,and lower SAVE scores,with statistically significant differences.ECMO cardiac complications,ECMO run time,and 24-hour lactate clearance rate post-ECMO were identified as risk factors for poor prognosis in ECPR patients.Conclusion ECMO cardiac complications,ECMO run time,and 24-hour lactate clearance rate post-ECMO are inde-pendent risk factors for in-hospital mortality in ECPR patients.