title: Incidence, duration and survival of ventricular fibrillation in out-of-hospital cardiac arrest patients in sweden.
abstract: The chance of survival from ventricular fibrillation (VF) is up to ten times higher than those with other cardiac arrest rhythms. To calculate the effect of out-of-hospital resuscitation organisations on survival, it is necessary to know the percentage of cardiac arrest patients initially in VF and the relationship between delay time to defibrillation and survival.
  
  
  OBJECTIVE
  To study the incidence of VF at the time of cardiac arrest and on first ECG, the duration of VF and the relation between time to defibrillation and survival.
  
  
  METHODS
  The Swedish Cardiac Arrest Registry has collected standardised reports on out-of-hospital cardiac arrests from ambulance organisations in Sweden, serving 60% of the Swedish population.
  
  
  RESULTS
  In 14065 cases of out-of-hospital cardiac arrest collected between 1990 and 1995, resuscitation was attempted in 10966 cases.
  
  
  BACKGROUND
  The first ECG showed VF in 43% of all patients. The incidence of VF at the time of cardiac arrest was estimated to be 60-70% in all patients and 80-85% in the cases with probable heart disease.
  
  
  METHODS
  The estimated disappearance rate of VF was slow. Thirty minutes after collapse approximately 40% of the patients were in VF.
  
  
  RESULTS
  Overall survival to 1 month was only 1.6% for patients with non-shockable rhythms and 9.5% for patients found in VF. With increasing time to defibrillation, the survival rate fell rapidly from approximately 50% with a minimal delay to 5% at 15 min.
  
  
  CONCLUSIONS
  This study suggests a high initial incidence of VF among out-of-hospital cardiac arrest patients and a slow rate of transformation into a non-shockable rhythm. The survival rate with very short delay times to defibrillation was approximately 50%, but decreased rapidly as the delay increased.
authors.affiliation: Department of Cardiology, Sahlgrenska University Hospital, SE-413 45, Göteborg, Sweden. mholmberg50@hotmail.com
authors.forename: M
authors.initials: M
authors.lastname: Holmberg
authors.forename: S
authors.initials: S
authors.lastname: Holmberg
authors.forename: J
authors.initials: J
authors.lastname: Herlitz
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D004632:Emergency Medical Services / Q000379:methods*; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011336:Probability; D012042:Registries; D012044:Regression Analysis; D012307:Risk Factors; D017678:Sex Distribution; D015996:Survival Rate; D013548:Sweden / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy*