Changing Incidence of Out-of-Hospital Ventricular Fibrillation, 1980-2000

CONTEXT: Recent reports from 2 European cities and an earlier observation from Seattle, Wash, suggest that the number of patients treated for out-of-hospital ventricular fibrillation (VF) has declined. OBJECTIVE: To analyze the incidence of cardiac arrest and to examine relationships among incidence, sex, race, age, and first identified cardiac rhythm in Seattle. DESIGN, SETTING, AND PATIENTS: Population-based study of all cardiac arrest cases with presumed cardiac etiology who received advanced life support from Seattle Fire Department emergency medical services during specified periods between 1979 and 2000. United States Census data for Seattle in 1980, 1990, and 2000 were used to determine incidence rates for treated cardiac arrest with adjustments for age and sex. MAIN OUTCOME MEASURES: Changes in incidence of cardiac arrest and initial recorded cardiac rhythm. RESULTS: The adjusted annual incidence of cardiac arrest with VF as the first identified rhythm decreased by about 56% from 1980 to 2000 (from 0.85 to 0.38 per 1000; relative risk RR, 0.44; 95% confidence interval CI, 0.37-0.53). Similar reductions occurred in blacks (54%; RR, 0.45; 95% CI, 0.26-0.79) and whites (53%; RR, 0.47; 95% CI, 0.38-0.58) and was most evident in men (57%; RR, 0.43; 95% CI, 0.35-0.53), in whom the baseline incidence was relatively high. When all treated arrests with presumed cardiac etiology were considered, that incidence decreased by 43% (RR, 0.58; 95% CI, 0.49-0.67) in men but negligibly in women, for whom a relatively low incidence of VF also declined but was offset by more cases with asystole or pulseless electrical activity. CONCLUSION: We observed a major decline in the incidence of out-of-hospital VF and in all cases of treated cardiac arrest presumably due to heart disease in Seattle. These changes likely reflect the national decline in coronary heart disease mortality.