Abstract 11969: Effects of Definition of Defibrillation Success on Predictability of Ventricular Fibrillation Waveform Analysis

Abstract

Introduction: Quantitative analysis of ventricular fibrillation (VF) waveform has the potential to optimize the timing of defibrillation by predicting defibrillation outcome. However, there is no consensus on the definition of defibrillation success in out-of-hospital settings. In the present study, we used a registry data of out-of-hospital cardiac arrest (OHCA) to investigate the effects of different definitions of defibrillation success on the predictability of amplitude spectrum area (AMSA). Methods: A total of 581 shocks from 264 OHCA patients with VF as the first recorded rhythm were included in this study.We determined the presence of VF, asystole or organized rhythm 120 seconds after shock delivery as the final outcome. In order to identify how different definitions of defibrillation success affect the predictive value of AMSA, we used 3 different definitions that were previously described in the literatures. (1) Termination of VF: A successful shock is defined as no presence of VF for 5 seconds or longer. (2) Return of organized electrical activity (ROEA): A successful shock is defined by an organized rhythm observed for at least 5 seconds after delivery of the shock. (3) Return of a potentially perfusing rhythm: An organized rhythm is restored with a heart rate greater than 40 beats/min, commencing within 60 seconds after shock delivery. Results: A total of 153 cases (26.3%) had an final outcome of organized rhythm. The defibrillation success rates were 72.1%, 49.2% and 27.0% when the 3 different definitions were used. The area under the receiver-operating-characteristic curve was 0.563 for termination of VF, 0.706 for organized rhythm, and 0.814 for return of potentially perfusing rhythm (p<0.001). Conclusion: AMSA’s ability to predict shock success varied strongly depending on which definition of shock success was used. Termination of VF may be a good measure of defibrillation efficacy for new onset of VF, while return of a potentially perfusing rhythm is clinically more relevant as a definition for defibrillation success in OHCA. AMSA had the highest predictive value when used with the outcome of potentially perfusing rhythm. This supports the assumption that AMSA is, at least to some extent, a measure of myocardial viability.