Circadian heart rate rhythms in Japanese centenarians

OBJECTIVE: To investigate age-associated changes in the circadian rhythm of the heart rate. DESIGN: The circadian rhythm was extracted from diurnal heart rate (KR) var iations, and patterns of HR rhythm were compared in centenarians and contro ls. SETTING: Centenarians living in the metropolitan area of Tokyo and in Aichi prefecture in 1992. PARTICIPANTS: Fifty centenarians underwent 24-hour ambulatory electrocardio gram (Holter) monitoring. The control group, comprised of 100 clinically he althy subjects who underwent similar Holter monitoring, was subdivided, by age, into two groups: the younger controls (age range 23 to 54 years, mean age 41) and the older controls (age range 55 to 82 years, mean age 69). MEASUREMENTS: Harmonic analysis was used to approximate the 24-hour RR inte rval (the interval between two neighboring R waves on the electrocardiogram ) data obtained by Holter monitoring to a summation of three cosine waves w ith 24-hour, 12-hour, and 8-hour periods. The power of the period was adjus ted for the goodness of curve-fit. The power of each period and the circadi an acrophase (the timing of the peak in a 24-hour rhythm) were compared amo ng the centenarians, older controls, and younger controls. HR rhythms were classified by k-means cluster analysis based on the power of the period. Th e prevalence of each pattern was compared among the three age groups. In th e centenarians, the relationship between clinical parameters (activities of daily living, cognitive function, nutritional status, and present illness) and patterns of HR rhythm was investigated. RESULTS: The power of the 24-hour period in the centenarians was significan tly smaller than that in the older (P < .05) and younger (P < .001) control s. The power of the 8-hour period in the centenarians was significantly lar ger than that in the younger controls (P < .05). Advances or delays in the circadian acrophase were frequently observed in the centenarians compared w ith the younger controls. The power of each period did not differ between c entenarians with (n = 11) and without (n = 39) overt diseases capable of al tering HR rhythms. Five patterns of HR rhythm were identified: 24-hour peri od dominant (n = 84), 24-hour+12-hour period (n = 18), 12-hour period domin ant (n = 11), 8-hour period dominant (n = 7), and low goodness of curve-fit (n = 30). The 8-hour period dominant pattern and the low goodness of curve -fit pattern were observed commonly in the centenarians, whereas the 24-hou r period dominant pattern and the 24-hour+12-hour period pattern were obser ved frequently in the younger controls. Patterns of HR rhythm were not rela ted to clinical parameters in the centenarians. CONCLUSIONS: The circadian rhythm of HR changed with aging: there was reduc tion in the power of the 24-hour period, augmentation in the power of the 8 -hour period, and a shift in the circadian acrophase.