Background
Many studies confirmed that dispatcher-assisted CPR (D-CPR) could improve survival from out-of-hospital cardiac arrest (OHCA) by significant improvement of bystander-CPR (B-CPR) rates. The aim of this study was to confirm relation between D-CPR implementation, incidence of cardiac arrest patients found by EMS with ventricular fibrillation (VF OHCA) and survival from VF OHCA from long-term (15 years) perspective. 
Method
This is a retrospective analysis of Prague Utstein-style OHCA registry from the beginning of D-CPR implementation (2003) until the end of 2018. Survival from cardiac arrest was defined as survival with cerebral performance category 1 or 2 during 30 days follow-up after OHCA. 
Results 
During first ten years of D-CPR implementation, B-CPR rates increased from 13,6%  to 81,0% (p<0,0001) and then remained more or less stable for following 6 years. This process was in strong correlation with VF OHCA incidence (Pearson R score = 0,684; P-Value = 0,003) as well as with VF OHCA survival rate (Pearson R score = 0,782; P-value = 0,00011).  
Conclusion
VF OHCA incidence as well as VF OHCA survival rates were in a strong correlation with D-CPR implementation as measured by B-CPR ratios. This supports the hypothesis that D-CPR increases survival from OHCA not only by improving survival rates, but also by keeping more patients with ventricular fibrillation running until EMS arrival.

7 - Implementation of Dispatcher-assisted CPR was associated with increased number of cardiac arrest patients found by EMS with ventricular fibrillation