title: Recurrent ventricular fibrillation: experience with first responders prior to advanced life support interventions.
abstract: OBJECTIVE
  Following defibrillation, ventricular fibrillation (VF) frequently recurs during out-of-hospital cardiac arrest (OHCA). Prior studies have reported conflicting results regarding its association with survival. The aim of this study was to examine the impact of recurrent VF in the presence of first responders before advanced life support (ALS) interventions.
  
  
  METHODS
  Electrocardiographic data from first responder automated external defibrillators (AEDs) were analyzed. A successful shock was defined as termination of VF for 5s or longer. Recurrent VF was defined as any VF that occurred after a successful shock. The primary outcome was neurologically intact survival to hospital discharge (CPC 1-2).
  
  
  RESULTS
  108 patients within our emergency system experienced a witnessed VF arrest. Of these, 73 (68%) had at least one recurrence of VF. Median time to recurrence of VF was 25s [interquartile range (IQR) 11-66s]. Median time in recurrent VF was 180s (IQR 105-266s). Survival was observed in 25 (71%) of patients with no recurrent VF and in 36 (49%) who had recurrence. Recurrent VF was associated with a lower odds of survival on univariate analysis (OR 0.39, 95% CI 0.16-0.92, p=0.0325). After adjusting for bystander CPR, gender and age, recurrent VF had a similar direction of effect but was no longer significantly associated with neurologically intact survival (OR 0.44, 95% CI 0.17-1.11, p=0.081).
  
  
  CONCLUSIONS
  In the presence of first responders, VF recurred in 68% of patients. Recurrent VF was associated with a lower odds of survival, though its prognostic significance appeared to be blunted when considered in light of confounding variables. Recurrent VF may have significant survival implications, and further studies to assess its prognostic significance should be performed.
authors.affiliation: Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Telesz
authors.affiliation: Department of Emergency Medicine, Division of Emergency Medicine Research, Mayo Clinic College of Medicine, Rochester, MN, USA; Knowledge and Evaluation Research Unit, Rochester, MN, USA.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Hess
authors.affiliation: Department of Health Sciences Research, Division of Biostatistics, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Atkinson
authors.affiliation: Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN, USA; Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA; City of Rochester Early Defibrillation Program, Rochester, MN, USA. Electronic address: white.roger@mayo.edu.
authors.forename: Roger D
authors.initials: RD
authors.lastname: White
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D047548:Defibrillators; D004554:Electric Countershock / Q000295:instrumentation*; D004562:Electrocardiography; D004632:Emergency Medical Services / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000209:etiology / Q000628:therapy*; D011379:Prognosis; D012008:Recurrence; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000150:complications / Q000628:therapy*
keywords: Emergency medical services; Out-of-hospital cardiac arrest; Sudden cardiac death; Ventricular fibrillation