5 MINUTE RECORDINGS OF HEART-RATE-VARIABILITY FOR POPULATION STUDIES - REPEATABILITY AND AGE-SEX CHARACTERISTICS

Objective-To evaluate the stability of short recordings of heart rate variability (KRV) with time, and the association of HRV with age and s ex. Design-Five minute Holter recordings were made twice over a two mo nth interval (tracking study). In addition, HRV was measured in a cros s sectional study. Setting-Residents of II Israeli kibbutzim were exam ined in their settlements. Subjects-32 men and 38 women (aged 31-67) p articipated in the tracking study and 294 (aged 35-65) were involved i n the cross sectional study. Main outcome measures-Time and frequency domain analyses on Holter recordings were undertaken in two breathing conditions: spontaneous and controlled breathing (15 respirations per minute). Regression was used to assess the relations of sex, age, hear t rate, and logarithmically transformed HRV indices. Results-HRV measu res were highly consistent with time with correlations of 0.76-0.80 fo r high frequency and total power. Geometric mean total power declined with age by 45% in men and 32% in women, and was lower by 24% among wo men than among men tall p less than or equal to 0.005). Men had a 34% higher very low and low frequency power and a higher ratio of low to h igh frequency power (p < 0.001). Conversely, high frequency power in w omen represents a greater proportion of total power than in men. Concl usion-Short recordings of HRV in a non-laboratory setting are stable o ver months and therefore characteristic of an individual. Strong age a nd sex effects were evident. HRV derived from short recordings can be informative in population based studies.