Background: Cardiopulmonary resuscitation (CPR) is initiated in hospitalized children with bradycardia and poor perfusion. However, it is unknown how often these children progress to pulseless in-hospital cardiac arrest (IHCA) despite CPR, and whether survival differs from primary pulseless IHCA. Methods: In Get With The Guidelines-Resuscitation (2000-2016), we identified all pediatric patients (age>30 days, <18 years) receiving CPR, and assessed the prevalence and predictors of survival among those progressing from bradycardia to pulselessness after initiation of CPR using multilevel Poisson regression that accounted for the pulseless rhythm. Results: Overall, 5592 pediatric patients were treated with CPR, of whom over half (2799) were for bradycardia with poor perfusion and the remaining 2793 were primary pulseless IHCAs. Among those with bradycardia, 869 (31%, or 16% of entire cohort) progressed to pulselessness after a median of 3 min of CPR (IQR 1- 9). Survival to discharge was 70% for bradycardia without pulselessness, 30% with bradycardia progressing to pulselessness, and 38% with primary pulseless IHCA (P<.001). Children who became pulseless while receiving CPR for bradycardia had a 19% lower likelihood (RR 0.81 [0.70 - 0.93]) of surviving to hospital discharge than those initially pulseless. Among children who progressed to pulselessness while receiving CPR for bradycardia, longer time to pulselessness was an independent predictor of lower survival (ref: <2 min, for 2-5 min: RR 0.54 [0.41 - 0.70]; for >5 min: RR 0.41 [0.32 - 0.53], Figure ). Conclusions: Among non-neonatal pediatric patients in whom CPR is initiated, half have bradycardia with poor perfusion, and nearly one-third of these progress to IHCA despite CPR. Survival was lower for pediatric patients who subsequently became pulseless as compared to those who were initially pulseless. These findings have implications for care delivery and profiling hospital performance for pediatric IHCA.