title: Predictors of resuscitation outcome in a swine model of VF cardiac arrest: A comparison of VF duration, presence of acute myocardial infarction and VF waveform.
abstract: BACKGROUND
  Factors that affect resuscitation to a perfusing rhythm (ROSC) following ventricular fibrillation (VF) include untreated VF duration, acute myocardial infarction (AMI), and possibly factors reflected in the VF waveform. We hypothesized that resuscitation of VF to ROSC within 3min is predicted by the VF waveform, independent of untreated VF duration or presence of acute MI.
  
  
  METHODS
  AMI was induced by the occlusion of the left anterior descending coronary artery. VF was induced in normal (N=30) and AMI swine (N=30). Animals were resuscitated after untreated VF of brief (2min) or prolonged (8min) duration. VF waveform was analyzed before the first shock to compute the amplitude-spectral area (AMSA) and slope.
  
  
  RESULTS
  Unadjusted predictors of ROSC within 3min included untreated VF duration (8min vs 2min; OR 0.11, 95%CI 0.02-0.54), AMI (AMI vs normal; OR 0.11, 95%CI 0.02-0.54), AMSA (highest to lowest tertile; OR 15.5, 95%CI 1.7-140), and slope (highest to lowest tertile; OR 12.7, 95%CI 1.4-114). On multivariate regression, untreated VF duration (P=0.011) and AMI (P=0.003) predicted ROSC within 3min. Among secondary outcome variables, favorable neurological status at 24h was only predicted by VF duration (OR 0.22, 95% CI 0.05-0.92).
  
  
  CONCLUSIONS
  In this swine model of VF, untreated VF duration and AMI were independent predictors of ROSC following VF cardiac arrest. AMSA and slope predicted ROSC when VF duration or the presence of AMI were unknown. Importantly, the initial treatment of choice for short duration VF is defibrillation regardless of VF waveform.
authors.affiliation: The Sarver Heart Center, The University of Arizona College of Medicine, 1501 N. Campbell Ave., Tucson, AZ 85724-5037, United States. jindik@email.arizona.edu
authors.forename: Julia H
authors.initials: JH
authors.lastname: Indik
authors.forename: Madhan
authors.initials: M
authors.lastname: Shanmugasundaram
authors.forename: Daniel
authors.initials: D
authors.lastname: Allen
authors.forename: Amanda
authors.initials: A
authors.lastname: Valles
authors.forename: Karl B
authors.initials: KB
authors.lastname: Kern
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Hilwig
authors.forename: Mathias
authors.initials: M
authors.lastname: Zuercher
authors.forename: Robert A
authors.initials: RA
authors.lastname: Berg
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016887:Cardiopulmonary Resuscitation; D004195:Disease Models, Animal; D004562:Electrocardiography; D006323:Heart Arrest / Q000503:physiopathology* / Q000628:therapy; D009203:Myocardial Infarction / Q000503:physiopathology* / Q000628:therapy; D011237:Predictive Value of Tests; D012044:Regression Analysis; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000628:therapy