Abstract 188: Temporal Changes in Morphological Characteristics of Ventricular Fibrillation from Out-of-Hospital Cardiac Arrest in an Asian Community

Abstract

Introduction: Ventricular fibrillation (VF) is the most common arrhythmia causing out-of-hospital cardiac arrest (OOHCA) and defibrillation remains the mainstay of its treatment. Successful defibrillation is linked to VF morphology characteristics, and is affected by VF duration, quality of cardiopulmonary resuscitation (CPR) and emergency medical service (EMS) responsiveness. This study aimed at comparing VF morphology characteristics and their relationships with patients and EMS characteristics, as well as outcomes, in an Asian community. Method: Electrocardiographic recordings of VF signals from automated external defibrillators (AEDs) in 2008 to 2012 were obtained from OOHCA subjects in Taipei city, a metropolitan with 2.65 million residents in 272km2. Amplitude spectrum analysis (AMSA) and DFAα2 were calculated and compared year by year in the study period. Results: A total of 612 OOHCA subjects with VF were included for analysis. Both DFA and AMSA changed significantly over time (χ 2 for trend: -0.128 for DFA, p<0.01; 0.092 for AMSA, p=0.02). There was no change in gender, age, and bystander CPR rates; however, in later years there were more witnessed arrests, shortened EMS responses, and better sustained (>2 hr) return of spontaneous circulation (ROSC) and neurological outcomes (CPC 1&2). The time trend for DFAα2 (OR 0.98, CI 0.96-0.99, p=0.003), but not for AMSA (OR 1.07, CI 0.99-1.14), remained after adjustment for confounders. Both DFAα2 and AMSA were associated with sustained ROSC (DFA OR 0.08, CI 0.04-0.18, p<0.001; AMSA OR 1.18, CI 1.01-1.38, p=0.03) and CPC 1&2 (DFA OR 0.04, CI 0.01-0.16, p<0.001; AMSA OR 1.30, CI 1.07-1.57, p=0.008) in multiple regression models. Conclusions: DFAα2 and AMSA, two important VF characteristics, changed significantly over time in an Asian community, and were associated with improved outcomes. This might reflect improvement in community chain of survival especially among EMS responses and community quality of CPR.