Ventricular Fibrillation Following Out-of-hospital Cardiac Arrest

The majority of survivors suffering an out-of-hospital cardiac arrest (OHCA) are those who initially present with a shockable rhythm, which is usually ventricular fibrillation (VF). When untreated, VF progresses to asystole over a short period of time so the percentage of those with a survivable rhythm also decreases with time. There is relatively little data exploring the initial rate of VF and the time course of its subsequent progression to a non-shockable rhythm. An understanding of this data will give a better picture of how potentially survivable rhythms (VF) change with time and guide the response times that are required to ensure arrival before VF deteriorates to asystole. The Investigators will use the UK OHCA outcomes database to examine the percentage of patients presenting with VF as the initial rhythm according to time since collapse in order to establish the rate at which VF deteriorates to asystole.