@article {859, title = {Sometimes higher heart rate variability is not better heart rate variability: results of graphical and nonlinear analyses.}, journal = {J Cardiovasc Electrophysiol}, volume = {16}, year = {2005}, month = {2005 Sep}, pages = {954-9}, abstract = {

OBJECTIVE: To determine the prevalence and effect on traditional heart rate variability (HRV) indices of abnormal HRV patterns in the elderly.

METHODS: Hourly Poincar{\'e} plots and plots of spectral HRV from normal-to-normal interbeat intervals and hourly nonlinear HRV values were examined in a subset of 290 consecutive participants in the Cardiovascular Health Study. Only subjects in normal sinus rhythm with > or = 18 hours of usable data were included. Eligible subjects were 71 +/- 5 years. During 7 years of follow-up, 21.7\% had died. Hours were scored as normal (0), borderline (0.5), or abnormal (1) from a combination of plot appearance and HRV. Summed scores were normalized to 100\% to create an abnormality score (ABN). Short-term HRV versus each 5th percentile of ABN was plotted and a cutpoint for markedly increased HRV identified. The t-tests compared HRV for subjects above and below this cutpoint. Cox regression evaluated the association of ABN and mortality.

RESULTS: Of 5,815 eligible hourly plots, 64.4\% were normal, 14.5\% borderline, and 21.1\% abnormal. HR, SDNN, SDNNIDX, ln VLF and LF power, and power law slope did not differ by the cutpoint for increased short-term HRV, while SDANN and ln ULF power were significantly lower for those above the cutpoint. However, many HRV indices including LF/HF ratio and normalized LF and HF power were significantly different between groups (P < 0.001). Increased ABN was significantly associated with mortality (P = 0.019). Despite similar values for many HRV indices, being in the group above the cutpoint was significantly associated with mortality (P = 0.04).

CONCLUSIONS: Abnormal HR patterns that elevate many HRV indices are prevalent among the elderly and associated with higher risk of mortality. Consideration of abnormal HRV may improve HRV-based risk stratification.

}, keywords = {Aged, Aged, 80 and over, Algorithms, Arrhythmia, Sinus, Cohort Studies, Diagnosis, Computer-Assisted, Electrocardiography, Female, Heart Rate, Humans, Male, Models, Cardiovascular, Nonlinear Dynamics, Numerical Analysis, Computer-Assisted, Prevalence, Proportional Hazards Models, Reproducibility of Results, Risk Assessment, Risk Factors, Sensitivity and Specificity, United States}, issn = {1045-3873}, doi = {10.1111/j.1540-8167.2005.40788.x}, author = {Stein, Phyllis K and Domitrovich, Peter P and Hui, Nelson and Rautaharju, Pentti and Gottdiener, John} }