Introduction
Registry of the cardiac arrests in the Prague city is recording cases from the year 2003. We had analysed data of all cardiac arrest according to the place of onset compared to other factors like bystander CPR provided, initial rhythm, achieving of ROSC and outcome.

Methods
Retrospective analysis of the registry of the cardiac arrests in the capital city of the Czech Republic which were dealt with by Prague EMS in the years 2003 to 2018. The data in the registry is collected in the scope and structure that corresponds to the Utstein Protocol, valid at the time of data collection.

Results
Lay CPR is provided more often on a public places than at home (OR 0.8061, CI 95% 0.7384 to 0.8800) and also more on a public places than at healthcare facilities (OR 1.6451, CI 95% 1.3126 to 2.0619). There are also differences in the initial rhythm compared to the place of onset (p<0.01).
ROSC is achieved more often on a public places and in healthcare facilities than at home (OR 1.4325,  CI 95% 1.2986 to 1.5802, p<0.01; OR 1.3961, CI 95% 1.1089 to 1.7578, p<0.01). Out-of-hospital cardiac arrest in a public places and also in a healthcare facilities is associated with better outcome than cardiac arrests at home (p<0.01).

Conclusion
Understanding the aetiology of cardiac arrest in relation to the environment and other factors can have a major impact, for example, on the deployment of AEDs in public places, but also on equipping general practitioners or nursing homes. This presentation represents a big dataset from a capital city of a European country, which can be generalized also to other countries.

5 - Place of Onset of Cardiac Arrests in the Prague city between 2003 and 2018