Abstract 217: Circadian Variation in Out-of-Hospital Cardiac Arrests in a Japanese Patient Population: Analysis of a Nationwide Population-Based Registry 2005–2008
Background: It is well known that acute cardiovascular events and sudden cardiac death occur most frequently in the morning. These data were derived from Western countries. This study aimed to determine if there is a circadian variation in the presentation of all-Japan cohort of patients with out-of-hospital cardiac arrests, and if there are significant factors that may affect circadian variability.
Methods: We referred a database of a prospective, nationwide, population-based registry of out-of-hospital cardiac arrests that is conducted by the Fire and Disaster Management Agency of Japan between January 2005 and December 2008. The records are based on the standardized Utstein style. Patients who had sudden collapse witnessed by family members, friends, or bystanders of the public were enrolled. We assessed the incidence of the cardiac arrest as hourly data (i.e., circadian variation). Etiology of the cause was categorized into two types: cardiac etiology and noncardiac etiology including external cause and others.
Results: During the 4-year period, 431,968 patients were registered and 173,767 patients had out-of-hospital cardiac arrests witnessed by bystanders. Of the patients, exact time of collapse or certain age was not determined in 69 patients. Finally, 173,698 patients were enrolled for assessment. A gradual circadian rhythm was seen with three zeniths in the morning (8:00–9:00), noon (12:00–13:00), and evening (18:00–19:00). The magnitude of these three zeniths was almost the same. Older (≥80 years) patients had more apparent circadian variation than younger (<60 years) patients. There were no remarkable differences in the circadian pattern between men and women. In 95,469 patients with cardiac etiology, cardiac arrests had a circadian rhythm that was characterized by one zenith in the morning. Regards as 78,229 patients with noncardiac etiology, it was characterized by three zeniths, but the evening and noon zeniths were greater than the morning zenith.
Conclusions: Out-of-hospital cardiac arrests in Japanese patients have a gradual circadian variation with three zeniths, with morning predominance in cardiac etiology and noon and evening predominance in noncardiac etiology. Aging affects an apparent circadian variation.
- © 2010 by American Heart Association, Inc.