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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