title: Incidence and survival outcome according to heart rhythm during resuscitation attempt in out-of-hospital cardiac arrest patients with presumed cardiac etiology.
abstract: Knowledge about heart rhythm conversion from non-shockable to shockable rhythm during resuscitation attempt after out-of-hospital cardiac arrest (OHCA) and following chance of survival is limited and inconsistent.
  
  
  
  We studied 13,860 patients with presumed cardiac-caused OHCA not witnessed by the emergency medical services from the Danish Cardiac Arrest Register (2005-2012). Patients were stratified according to rhythm: shockable, converted shockable (based on receipt of subsequent defibrillation) and sustained non-shockable rhythm. Multiple logistic regression was used to identify predictors of rhythm conversion and to compute 30-day survival chances.
  
  
  
  Twenty-five percent of patients who received pre-hospital defibrillation by ambulance personnel were initially found in non-shockable rhythms. Younger age, males, witnessed arrest, shorter response time, and heart disease were significantly associated with conversion to shockable rhythm, while psychiatric- and chronic obstructive pulmonary disease were significantly associated with sustained non-shockable rhythm. Compared to sustained non-shockable rhythms, converted shockable rhythms and initial shockable rhythms were significantly associated with increased 30-day survival (Adjusted odds ratio (OR) 2.6, 95% confidence interval (CI): 1.8-3.8; and OR 16.4, 95% CI 12.7-21.2, respectively). From 2005 to 2012, 30-day survival chances increased significantly for all three groups: shockable rhythms, from 16.3% (CI: 14.2%-18.7%) to 35.7% (CI: 32.5%-38.9%); converted rhythms, from 2.1% (CI: 1.6%-2.9%) to 5.8% (CI: 4.4%-7.6%); and sustained non-shockable rhythms, from 0.6% (CI: 0.5%-0.8%) to 1.8% (CI: 1.4%-2.2%).
  
  
  
  Converting to shockable rhythm during resuscitation attempt was common and associated with nearly a three-fold higher odds of 30-day survival compared to sustained non-shockable rhythms.
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark. Electronic address: shahzleen@gmail.com.
authors.forename: Shahzleen
authors.initials: S
authors.lastname: Rajan
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark; Emergency Medical Services Copenhagen, University of Copenhagen, Denmark.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Folke
authors.affiliation: Department of Clinical Epidemiology, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Steen Møller
authors.initials: SM
authors.lastname: Hansen
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark; Duke Clinical Research Institute, Duke University, Durham, NC, United States.
authors.forename: Carolina Malta
authors.initials: CM
authors.lastname: Hansen
authors.affiliation: Department of Anesthesiology & Clinical Medicine, Aalborg University, Aalborg University Hospital, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Kragholm
authors.affiliation: Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gerds
authors.affiliation: Emergency Medical Services Copenhagen, University of Copenhagen, Denmark.
authors.forename: Freddy K
authors.initials: FK
authors.lastname: Lippert
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark.
authors.forename: Lena
authors.initials: L
authors.lastname: Karlsson
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, Denmark.
authors.forename: Sidsel
authors.initials: S
authors.lastname: Møller
authors.affiliation: Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.affiliation: The National Institute of Public Health, University of Southern Denmark, Denmark.
authors.forename: Gunnar H
authors.initials: GH
authors.lastname: Gislason
authors.affiliation: Department of Health, Science and Technology, Aalborg University, and Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
authors.affiliation: Emergency Medical Services Copenhagen, University of Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Wissenberg
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D002318:Cardiovascular Diseases / Q000150:complications*; D015897:Comorbidity; D004554:Electric Countershock / Q000379:methods* / Q000401:mortality; D004632:Emergency Medical Services / Q000379:methods; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D015999:Multivariate Analysis; D058687:Out-of-Hospital Cardiac Arrest / Q000145:classification / Q000401:mortality*; D012042:Registries; D013997:Time Factors; D016896:Treatment Outcome
keywords: Arrhythmia; Converted rhythm; Defibrillation; Epidemiology; Out-of-hospital cardiac arrest; Survival