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Aims and Objectives There are few population-level studies which describe the epidemiology of out-of-hospital cardiac arrests (OHCAs) with persistent shockable rhythms, which we pragmatically define as any OHCA that receives three or more shocks at any point. Our aim was to describe this patient cohort in England for the first time.Method and Design This was a multicentre, retrospective, observational, registry study using data from England’s national OHCA outcomes (OHCAO) registry. We included adult non-traumatic OHCAs between 1st January 2023 and 31st December 2024 when Emergency Medical Services (EMS) attempted resuscitation and they received three or more shocks at any point. Patient demographics, OHCA characteristics, and treatments were recorded, Outcomes were return of spontaneous circulation (ROSC) at any point and 30-day survival. The Chi squared test was used to compare proportions, with p < 0.05 taken as significant.Results and Conclusion We included 7,325 patients (median age 68.7 years, 79.9% male) out of 58,880 recorded OHCAs in the study period. OHCAs were commonly witnessed (n = 5,602, 76.5%), received bystander CPR (n = 5,432, 74.2%), and presented with shockable 1st rhythms (n = 5,167, 70.5%). The median number of shocks received was 5 (IQR 4 – 8), whilst 6,726 (91.8%) and 5,564 (76.0%) patients received adrenaline and amiodarone respectively. ROSC was achieved in 3,376 patients (46.1%) and 1,194 patients (16.3%) survived to 30 days. In OHCAs with persistent shockable rhythms after a shockable 1st rhythm, survival was greater compared to OHCAs which developed persistent shockable rhythms after a non-shockable 1st rhythms (22.2% v 1.9%, p < .001, Figure 1).There is a tenfold survival advantage to an initial shockable rhythm compared to developing a persistent shockable rhythm later, although a plateau effect exists beyond ten shocks. Of note, survival for persistent shockable rhythms is still better than overall survival from OHCA in England.Abstract 4515 Figure 1Cumulative survival according to total shocks received for OHCAs with shockable and non-shockable 1st rhythms