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Table 4 Frequency, time and nonlinear domain analysis of heart rate variability parameters across systolic blood pressure natural quartiles among healthy individuals (non-diabetes, hypertension and cardiovascular conditions)

From: Systolic blood pressure but not electrocardiogram QRS duration is associated with heart rate variability (HRV): a cross-sectional study in rural Australian non-diabetics

Heart rate variability Systolic blood pressure (mm Hg)
70–120 (n = 82) 121–130 (n = 43) 131–145 (n = 39) 146–220 (n = 14) p-value
n Mean (SD) n Mean (SD) n Mean (SD) n Mean (SD)
Frequency domain, mean (SD)
 Total power (ms2) 69 1282.4 (750.7) 38 1622.8 (843.6) 34 1046.5 (640.2) 13 1326 (810.5) 0.016
 HF (ms2) 65 197.3 (135.1) 36 222.9 (130.5) 34 140.6 (108.1) 14 162.8 (136.2) 0.046
 LF (ms2) 69 321.9 (203.4) 36 320.9 (190.2) 33 234 (166.8) 14 305.3 (214.3) 0.21
 HF In 77 5.4 (1.1) 40 5.5 (0.9) 33 4.8 (1.1) 12 4.7 (1.0) 0.0064
 LF In 78 5.8 (1.0) 40 5.8 (0.9) 32 5.5 (0.9) 12 5.6 (0.7) 0.54
 HF norm (v) 81 40.6 (16.1) 43 42.1 (16) 39 38.3 (18.4) 14 31.4 (13.4) 0.17
 LF norm (v) 82 57.1 (16.4) 43 55.2 (15.3) 39 60.2 (18.7) 14 66.8 (12.8) 0.10
 LF/HF ratio 71 1.39 (0.7) 39 1.4 (0.8) 32 1.6 (0.9) 11 2.1 (1.0) 0.029
Time domain, mean (SD)
 SDNN (ms) 79 40.9 (14.1) 43 44.6 (13.1) 38 36.8 (13.1) 14 38.5 (13.9) 0.077
 RMSDD (ms) 75 25.8 (10.5) 40 27 (8.9) 37 21.9 (9.8) 13 19.6 (8.9) 0.025
Nonlinear analysis
 DFA α1 82 1.1 (0.2) 43 1.0 (0.3) 39 1.1 (0.3) 14 1.1 (0.2) 0.55
 DFA α2 82 0.9 (0.2) 43 1.0 (0.2) 36 1.0 (0.1) 14 1.0 (0.1) 0.68
 DFA32 32 92.6 (31.5) 22 87.9 (30.9) 11 82.4 (31.1) 8 88 (27.2) 0.81
 ApEN 81 1.26 (0.14) 39 1.18 (0.18) 36 1.16 (0.22) 12 1.06 (0.22) 0.001
  1. SD standard deviation, HF high frequency, LF low frequency, norm normalized, SDNN standard deviation of R-R intervals, RMSDD root mean square of successive difference of RR, DFA detrended fluctuation analysis, ApEN approximate entropy