Incidence and Survival Rate of In-Hospital Cardiac Arrest Following Open-Heart Surgery: A Five-Year Retrospective Cohort Study in Western Iran Running title: Incidence and Survival of Cardiac Arrest After Cardiac Surgery

Background Cardiac arrest (CA) is a life-threatening complication following open-heart surgery, with a reported incidence of 0.7% to 5.2% and mortality rates exceeding 80%. Despite advances in perioperative care, survival outcomes remain suboptimal, and comprehensive data on resuscitation outcomes and survival rates in this high-risk population are limited, particularly in developing regions. This study aimed to determine the incidence, survival rates, outcomes, and predictors of cardiopulmonary resuscitation (CPR) in patients who experienced in-hospital cardiac arrest after open-heart surgery. Methods This retrospective cohort study was conducted at a tertiary cardiac center in Kermanshah, Iran. All patients who underwent open-heart surgery between March 2019 and February 2024 and subsequently experienced in-hospital cardiac arrest requiring CPR were included. Data on demographics, clinical characteristics, surgical details, resuscitation interventions, and outcomes were extracted from medical records using a standardized Utstein-style checklist. The primary outcome was return of spontaneous circulation (ROSC). Secondary outcomes included survival to hospital discharge, 30-day survival, 6-month survival, and neurological status. Multivariate logistic regression analysis was used to identify independent predictors. Results Among 5,024 open-heart surgeries, cardiac arrest occurred in 256 patients (5.09%), of whom 242 were included in the final analysis. The mean age was 62.42 ± 11.63 years, and the mean CPR duration was 40.57 ± 11.27 minutes. ROSC was achieved in 58 patients (24.0%). Survival to hospital discharge was 16.5% (40/242), 30-day survival was 16.1% (39/242), and 6-month survival was 11.2% (27/242). Favorable neurological outcome was observed in 31 of the 40 survivors (77.5%). Independent predictors of ROSC included age < 62 years (p = 0.005), history of coronary artery disease (p = 0.001), and administration of calcium gluconate during CPR (p < 0.001). Conclusion Survival rates after cardiac arrest following open-heart surgery remain low, and neurological impairment is common among survivors. Younger age, pre-existing coronary artery disease, and targeted pharmacological interventions may improve outcomes. These findings highlight the need for optimized perioperative monitoring, standardized CPR protocols, and enhanced post-resuscitation care to improve survival in this vulnerable population.