Abstract Body (Do not enter title and authors here): Background: Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality worldwide, with prompt defibrillation being crucial for improving survival rates. Public access defibrillators (PADs) offer a means for rapid intervention outside hospital settings. This systematic review evaluates the effectiveness of PADs in OHCA scenarios.

Method: A systematic review was conducted following PRISMA guidelines. Global studies from 2000 onwards assessing bystander and emergency medical service (EMS) interventions during OHCA, particularly focusing on AED usage, were included. Data synthesis and quality assessment were performed using established frameworks, including Covidence for screening and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) framework for risk of bias assessment.

Results: Thirty studies met inclusion criteria. PAD deployment significantly improved survival outcomes, with better results observed in public settings compared to private residences. Bystander-initiated defibrillation correlated with higher survival rates and improved neurological outcomes. School and airport settings demonstrated particularly favorable outcomes due to AED accessibility and trained personnel. The combination of CPR and AED use by bystanders markedly increased survival chances compared to EMS intervention. The difference in survival rates between bystander-initiated defibrillation and EMS intervention ranged from 5% to 42%. Regarding neurological outcomes, the difference between bystander-initiated defibrillation and EMS intervention ranged from 16.4% to 34%.

Discussion: The review underscores the critical role of immediate bystander response and PAD accessibility in OHCA survival. Strategic AED placement in high-risk areas and widespread CPR training are essential for enhancing outcomes. Challenges include variable data collection methods and limited benefits in certain OHCA scenarios.

Conclusion: Bystander interventions, including CPR and AED usage, significantly increase OHCA survival rates. Promoting widespread CPR training, strategic AED placement, and continuous outcome monitoring are vital for improving OHCA outcomes. Further research is warranted to address challenges and optimize intervention strategies.