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Figure 15. Unadjusted survival outcomes by who performed first defibrillation in the population with a shockable presenting rhythm.
With 17.5% of OHCAs occurring in public locations, the role of public access AEDs and community training 
have a large role to play in early defibrillation. However, the application of AEDs applied by bystanders 
remains relatively low, occurring after only 13.9% of public arrests.
In 2025, 31.2% (n=43,842) of CARES patients were defibrillated in the field. Among these patients, 
5.8% were initially defibrillated by a bystander, while 26.2% and 68.0% were first defibrillated by a first 
responder or EMS personnel, respectively.
Reducing delays to defibrillation leads to improved outcomes for patients in a shockable rhythm. 
Unadjusted outcomes for this subset of patients vary based on who performed the first defibrillation 
(Figure 15). The proportion of OHCA patients surviving to hospital discharge when first defibrillated by a 
bystander with an AED was 47%, compared to 28% of patients first shocked by a first responder and 27% 
by responding EMS personnel.
Early Defibrillation

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