Twenty-Four-Hour Variation in the Occurrence and Survival of Potentially Lethal Ventricular Tachyarrhythmia

The temporal pattern in the occurrence and primary outcome of resuscitation of out-of-hospital ventricular fibrillation/tachycardia was studied. The onset time of 117 cases of tachyarrhythmia exhibited a double-peaking 24-h variation with a first prominent peak in the midmorning and a second less prominent one during the late afternoon and early evening hours. Survival after resuscitation also was time dependent, showing a quite different temporal pattern. Survival was lowest during the daytime and greatest (four to five times greater) during the night. The findings are consistent with the hypothesis that out-of-hospital ventricular fibrillation/tachycardia may be dependent on autonomic regulation.