Survivability of young sudden cardiac arrest by aetiology: insights from a state-wide adjudicated cardiac arrest registry

Abstract Background Identifying factors to improve survival following out-of-hospital cardiac arrest (OHCA) is important. Many OHCA registries do not document the underlying cause of OHCA and therefore cannot provide insights according to specific arrest aetiology. The aim of this study was to assess survivability of OHCA according to arrest aetiology. Methods A state-wide registry identified all patients aged 1 to 50 years who experienced OHCA in Victoria, Australia from April 2019 to April 2023. OHCA was ambulance-defined with cause of OHCA determined by adjudication against autopsy or hospital data. OHCA aetiology was classified into four categories; non-cardiac, coronary, cardiomyopathy or other cardiac (including unascertained cause). Results 2686 patients experienced OHCA (non-cardiac=1305, 48.6%, coronary=585, 21.8%, cardiomyopathy=250, 9.3%, other cardiac=537(282 unascertained), 20.0%), of whom 250 (9.3%) survived. Patients in the coronary group were older (median 45 years [interquartile range 40-48 years], p=0.0001), more likely to be male (83.6%, p<0.0001), have a witnessed arrest (44.6%, p<0.0001) and have an initial shockable rhythm (48.2%, p<0.0001) when compared to other categories. Using the non-cardiac group as the reference group, adjusted odds ratio of survival (95% CI) were 1.65 (0.86-3.19) for cardiomyopathy, 2.51 (1.55-4.07) for other cardiac and 4.03 (2.51-6.49) for coronary causes of OHCA. Conclusion Odds of survival to hospital discharge following OHCA were four times higher in OHCA of coronary aetiology when compared with non-cardiac OHCA. Ongoing research into OHCA according to aetiology is needed to define subgroups, benchmark resuscitation performance more appropriately and identify patterns according to specific aetiologies to improve survival outcomes.