Letter by Manfredini et al Regarding Article, "Ambulance Density and Outcomes After Out-of-Hospital Cardiac Arrest: Insights From the Paris Sudden Death Expertise Center Registry".

We read with interest the article by Chocron and the Paris Sudden Death Expertise Center Investigators in a recent issue of I Circulation i ,[1] reporting that, in a large sample of cases of out-of-hospital cardiac arrests, a higher density of ambulances providing basic and advanced life support was associated with successful return of spontaneous circulation. 1 Chocron R Loeb T Lamhaut L Jost D Adnet F Lecarpentier E Bougouin W Beganton F Juvin P Marijon E Paris SDEC Investigators Ambulance density and outcomes after out-of-hospital cardiac arrest: insights from the Paris Sudden Death Expertise Center Registry. [Extracted from the article]