• T Jared Bunch and Roger D White.
• Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
• Resuscitation. 2005 Oct 1;67(1):51-4.

BackgroundThe 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.MethodsAll 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.ResultsThe 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].ConclusionThe 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.

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