TY - JOUR
T1 - Frailty and impaired cardiac autonomic control
T2 - New insights from principal components aggregation of traditional heart rate variability indices
AU - Varadhan, Ravi
AU - Chaves, Paulo H.M.
AU - Lipsitz, Lewis A.
AU - Stein, Phyllis K.
AU - Tian, Jing
AU - Windham, B. Gwen
AU - Berger, Ronald D.
AU - Fried, Linda P.
N1 - Funding Information:
This research was supported by the National Institute on Aging, Claude D. Pepper Older Americans Independence Centers , grant P30 AG021334 , and National Institutes of Health-National Center for Research Resources grant R37 AG19905 at the Johns Hopkins University School of Medicine.
PY - 2009/6
Y1 - 2009/6
N2 - Background. Age-related deterioration in homeostatic regulatory mechanisms leads to decreased complexity in their output. For example, the degradation of cardiac autonomic control results in loss of complexity in the heart rate signal. Frailty is a state of critically impaired homeostasis that results in heightened vulnerability to stressors. We propose a new measure of heart rate variability (HRV) to capture the impairment in cardiac autonomic control associated with frailty. Methods. Traditional time and frequency domain indices of HRV were obtained from 2-hour ambulatory electrocardiograms (ECGs) of 276 women (65-101 years old) in the Women's Health and Aging Study-I. Principal components analysis was conducted on the correlation matrix of HRV indices. Frailty was defined using a validated instrument. Regression models were used to evaluate associations of HRV measures with age, frailty, and 5-year mortality. Results. The first two principal components (PCs), PC1 and PC2, explained 90% of the variance in HRV indices. PC1 is the mean of log-transformed HRV indices. PC2 is a linear combination of log-transformed indices, with positive weights for very low frequency (VLF), low frequency (LF), and standard deviation of N-N intervals (SDNN), and negative weights for high frequency (HF), root-mean-squared differences of successive N-N intervals (RMSSD), and proportion of all N-N intervals that are larger than 50 ms (pNN50). Decreases in SDNN, VLF, LF, and LF/HF were associated with an increased risk of frailty. PC2 was more strongly associated with age (β = -.23, p < .001) and frailty (β = -.73, p < 10-5) than were the individual HRV indices and LF/HF. PC2 was also the best predictor of 5-year mortality (β = -.60, p < 10-6). Conclusions. Cardiac autonomic control, as reflected by HRV, is impaired in frailty. A new measure derived from PC aggregation of traditional HRV indices provides a compact summary of this impairment.
AB - Background. Age-related deterioration in homeostatic regulatory mechanisms leads to decreased complexity in their output. For example, the degradation of cardiac autonomic control results in loss of complexity in the heart rate signal. Frailty is a state of critically impaired homeostasis that results in heightened vulnerability to stressors. We propose a new measure of heart rate variability (HRV) to capture the impairment in cardiac autonomic control associated with frailty. Methods. Traditional time and frequency domain indices of HRV were obtained from 2-hour ambulatory electrocardiograms (ECGs) of 276 women (65-101 years old) in the Women's Health and Aging Study-I. Principal components analysis was conducted on the correlation matrix of HRV indices. Frailty was defined using a validated instrument. Regression models were used to evaluate associations of HRV measures with age, frailty, and 5-year mortality. Results. The first two principal components (PCs), PC1 and PC2, explained 90% of the variance in HRV indices. PC1 is the mean of log-transformed HRV indices. PC2 is a linear combination of log-transformed indices, with positive weights for very low frequency (VLF), low frequency (LF), and standard deviation of N-N intervals (SDNN), and negative weights for high frequency (HF), root-mean-squared differences of successive N-N intervals (RMSSD), and proportion of all N-N intervals that are larger than 50 ms (pNN50). Decreases in SDNN, VLF, LF, and LF/HF were associated with an increased risk of frailty. PC2 was more strongly associated with age (β = -.23, p < .001) and frailty (β = -.73, p < 10-5) than were the individual HRV indices and LF/HF. PC2 was also the best predictor of 5-year mortality (β = -.60, p < 10-6). Conclusions. Cardiac autonomic control, as reflected by HRV, is impaired in frailty. A new measure derived from PC aggregation of traditional HRV indices provides a compact summary of this impairment.
KW - Frailty
KW - Frequency domain indices
KW - Homeostatic impairment
KW - Mortality
KW - Principal components analysis
KW - Time-domain indices
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U2 - 10.1093/gerona/glp013
DO - 10.1093/gerona/glp013
M3 - Article
C2 - 19223607
AN - SCOPUS:66149096596
SN - 1079-5006
VL - 64
SP - 682
EP - 687
JO - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
JF - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
IS - 6
ER -