Circadian rhythm of hourly ventricular arrhythmia frequency in man

Three twenty-four hour electrocardiographic recordings from 164 untreated patients were analyzed. A clear, statistically significant, diurnal pattern in hourly ventricular arrhythmia frequency was found. It was consistent across days and between seven diagnostic groups. A high frequency Noon to 4:00 PM peak contrasted with a low frequency 1:00 AM to 5:00 AM trough with zero hourly frequencies not uncommonly present. These findings appear applicable to large ambulatory populations and may well influence the design of future investigations of modalities which alter ventricular arrhythmia frequency.