title: Trends in treated ventricular fibrillation in out-of-hospital cardiac arrest: ischemic compared to non-ischemic heart disease.
abstract: BACKGROUND
  The incidence of ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) treated by first responders has declined over the past decade. Since VF OHCA occurs primarily in the setting of severe coronary artery disease, primary and secondary prevention strategies may in part account for the decline. However, such strategies may not have a similar impact on non-ischemic arrest.
  
  
  METHODS
  All Rochester Minnesota residents who presented with a VF OHCA from 1991 to 2004, treated by emergency medical services (EMS), were included in the study. Incidence rates were calculated based on the population for Rochester during the time period. Changes over time were tested using Poisson regression models. The significance of the trends was estimated according to the Mantel-Haenszel test for association, and two-tailed p-values reported.
  
  
  RESULTS
  The overall incidence of EMS-treated VF OHCA in Rochester during the study period was 10.6 per 100,000 (95% CI 9.1-11.8). The incidence decreased significantly (p<0.001) over the study period [1991-1994: 18.2/100,000 (95% CI 13.4-21.9); 1995-1999: 11.8/100,000 (95% CI 10.4-17.9); 2000-2004: 8.7/100,000 (95% CI 6.0-13.0)]. The incidence of VF OHCA with ischemic heart disease also declined [1991-1994: 13.4/100,000 (95% CI 8.9-16.9); 1995-1999: 11.1/100,000 (95% CI 8.2-15.9); 2000-2004: 5.5/100,000 (95% CI 3.8-8.2), p<0.001]. In contrast, the incidence VF OHCA with non-ischemic heart disease increased [1991-1994: 2.1/100,000 (95% CI 1.13-3.1); 1995-1999: 2.3/100,000 (95% CI 1.9-3.7); 2000-2004: 2.9/100,000 (95% CI 2.0-3.4), p<0.001].
  
  
  CONCLUSIONS
  The incidence of VF OHCA is declining. The decline is attributable to the reduction of VF cardiac arrest with ischemic heart disease; suggesting an impact of treatment strategies targeted at coronary artery disease. The relative increasing incidence of non-ischemic VF OHCA suggests that more efforts are required to minimize mortality in this cohort population.
authors.affiliation: Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: T Jared
authors.initials: TJ
authors.lastname: Bunch
authors.forename: Roger D
authors.initials: RD
authors.lastname: White
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000379:methods / Q000706:statistics & numerical data*; D015331:Cohort Studies; D016001:Confidence Intervals; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D006323:Heart Arrest / Q000453:epidemiology* / Q000628:therapy*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D016012:Poisson Distribution; D011336:Probability; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis; D014505:Urban Population; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy