Predictive factors ofsuccessful return of spontaneous circulation(rosc) in out-of-hospital cardiacarrest

Introduction: Out-of-hospital cardiac arrest (OHCA) represents a global public health issue with high mortality rates. Resuscitation outcomes depend on various factors that may differ across populations and regions. Objective: To analyze the predictive factors of a successful return of spontaneous circulation (ROSC) in OHCA, considering the initiation of bystander cardiopulmonary resuscitation (CPR) before the arrival of emergency medical services (EMS), initial cardiac arrest rhythm, and regional differences. Methods: This prospective study included adult patients who experienced OHCA in the Republic of Croatia during 2024. Data were collected using the standardized Utstein template and included variables such as age, cause, location of the event, telephone-guided instructions, bystander CPR, initial rhythm, and signs of life at hospital handover. Data analysis was conducted using IBM SPSS Statistics 25,0. Categorical variables were analyzed using the χ² test, and binary logistic regression was applied to identify predictors of successful ROSC (p < 0.05). Results: Bystander CPR before the arrival of emergency services resulted in successful ROSC in 33,2 % of cases. Regarding the initial rhythm, ventricular fibrillation was associated with the highest ROSC success rate of 34.6 %. Regional differences were also observed, with variations in success rates between urban and rural areas, including the City of Zagreb. Conclusion: The importance of early bystander intervention and rapid defibrillation in improving OHCA outcomes has been confirmed. Ventricular fibrillation as the initial rhythm and regional disparities in emergency medical service access and infrastructure further influence the chances of successful ROSC, highlighting the need for targeted education and improved resource availability.