Prehospital study of survival outcomes from out-of-hospital cardiac arrest in ST-elevation myocardial infarction in Queensland, Australia (the PRAISE study).

Aim: Patients that experience an out-of-hospital cardiac arrest in the context of a paramedic-identified ST-segment elevation myocardial infarction are a unique cohort. This study identifies the survival outcomes and determinants of survival in these patients.

Methods: A retrospective analysis was undertaken of all patients, attended between 1 January 2013 and 31 December 2017 by the Queensland Ambulance Service, who had a ST-segment elevation myocardial infarction identified by the attending paramedic prior to deterioration into out-of-hospital cardiac arrest. We described the 'survived event' and 'survived to discharge' outcomes of patients and performed univariate analysis and multivariate logistic regression to identify factors associated with survival.

Results: In total, 287 patients were included. Overall, high rates of survival were reported, with 77% of patients surviving the initial out-of-hospital cardiac arrest event and 75% surviving to discharge. Predictors of event survival were the presence of an initial shockable rhythm (adjusted odds ratio 8.60, 95% confidence interval (CI) 4.16-17.76;  < 0.001) and the administration of prehospital medication for subsequent primary percutaneous coronary intervention (adjusted odds ratio 2.54, 95% CI 1.17-5.50;  = 0.020). These factors were also found to be associated with survival to hospital discharge, increasing the odds of survival by 13.74 (95% CI 6.02-31.32;  < 0.001) and 6.96 (95% CI 2.50-19.41;  < 0.001) times, respectively. The administration of prehospital fibrinolytic medication was also associated with survival in a subgroup analysis.

Conclusion: This subset of out-of-hospital cardiac arrest patients was found to be highly salvageable and responsive to resuscitative measures, having arrested in the presence of paramedics and presented with an identified reversible cause.