Incidence, outcome, and dynamics of out-of-hospital cardiac arrest in the city of Vienna between 2019 and 2023

Background: In coherent regions, key figures and trends of out-of-hospital cardiac arrest (OHCA) are vital to improve favourable outcomes. Since the last cardiopulmonary resuscitation (CPR) guideline update, comprehensive OHCA data of the metropolitan area of Vienna, Austria, have been scarce. Methods: This retrospective study analyzed adult non-traumatic OHCA cases in Vienna between 01/2019 and 12/2023. It assessed emergency medical service records and clinical patient data, and reports incidences, ROSC rates, survival to hospital discharge, and neurological outcome. Logistic regression assessed associations between outcomes and predictors, while Poisson regression examined incidence changes before, during, and after COVID-19 lockdowns. Results: During the observation period, the Emergency Medical Service Vienna started cardiopulmonary resuscitation (CPR) in a total of 7433 patients (77.1/100,000 population per year). Sustained return of spontaneous circulation (ROSC) was observed in 24.8%, survival to hospital discharge in 9.3%, and a Cerebral Performance Category Score (CPC) of 1 or 2 in 6.8%. Compared with previous literature, outcomes remained stable. However, in patients with witnessed cardiac arrest of suspected cardiac aetiology and an initial shockable rhythm, rates amounted up to 39% for hospital discharge and 29.6% for CPC 1 or 2. Similarly, patients with CPC 1 or 2 before CPR had better outcomes than the overall cohort. During COVID-19, there was a decline in all outcome parameters. Conclusions: Survival after OHCA in Vienna seems stable, but significant improvements in outcome parameters are seen in a "high outcome potential cohort" over the last 15 years. This reaffirms the need to continue focusing on rapid initiation of bystander CPR and early defibrillation.