Circadian rhythmicity of heart rates in centenarians

Abstract

Holter electrocardiography was used to study the circadian rhythm of heart rate in 50 centenarians living in Tokyo and in Aichi prefecture. As a control group, 50 healthy subjects aged under 65 years old underwent medical check-ups including Holter electrocardiography at Keio Health Consulting Center. Harmonic analysis was used to approximate the 24-h time-series data on the RR intervals to a summation of three cosine waves with 24-h, 12-h and 8-h periods. The power of each period was adjusted for the goodness of the curve-fit, and the powers of the centenarians were compared with those of the controls. Then all the subjects were classified by k-means cluster analysis into k groups based on the power of the period, and patterns of heart rate rhythms were then identified. The power of the 24-h period in centenarians (32.7 ± 16.0%) was significantly lower than that in controls (45.8 ± 17.8%). Although there were no significant differences in the powers of the 12-h and 8-h periods, the power of the 8-h period in centenarians (7.0 ± 8.4%) was slightly higher than that in controls (4.2 ± 3.3%). Advances or delays in acrophase (acrophasal shift) were more common in centenarians than in controls. Five patterns of heart rate rhythms were identified: 24-h period dominant (n=58). 24-h±12-h period (n=15), 12-h period dominant(n= 7), 8-h period augmented (n=7), and low curve-fitting (n=13). Both the 8-h period augmented pattern and the low curve-fitting pattern were more common in centenarians than in controls. Both the 24-h period dominant pattern and the 24-h+12-h period pattern were less common in centenarians than in controls. These data indicate that the circadian rhythm of heart rate changes with aging.