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. 2023 Sep 22;13:15814. doi: 10.1038/s41598-023-42615-y

Table 3.

Heart rate variability (HRV) by group over 24 h, day, and night period.

(A) Group Adjusted model Sex Age Group
PCS (n = 103) CAD (n = 103) Ctrl (n = 90) F p η2 p η2 p η2 p η2
M SD M SD M SD
Time-related variables (24 h)
 NN interval, ms 797.2 93.7 858.9 121.9 797.6 81.5 9.378  < 0.001 0.115  < 0.001 0.039 0.569 0.001 0.009§,* 0.032
 SDNN, ms 154.7 39.9 147.0 49.9 146.9 33.3 7.879  < 0.001 0.098  < 0.001 0.057 0.001 0.40 0.197 0.011
 SDANN, ms 139.4 39.0 130.7 46.1 130.0 32.3 6.355  < 0.001 0.080  < 0.001 0.050 0.010 0.023 0.105 0.015
 SDNN Index, ms 59.1 18.0 53.8 19.5 62.6 15.0 18.929  < 0.001 0.206  < 0.001 0.054  < 0.001 0.135 0.013* 0.029
 rMSSD, ms 42.2 20.2 36.4 20.4 36.4 14.1 8.311  < 0.001 0.103 0.002 0.032  < 0.001 0.055 0.046 0.021
 pNN50, % 9.1 8.0 9.3 11.1 11.7 8.5 13.719  < 0.001 0.159 0.011 0.022  < 0.001 0.130 0.268 0.009
 Triangular Index 39.8 11.3 37.3 14.0 40.8 9.1 6.844  < 0.001 0.086 0.062 0.012  < 0.001 0.063 0.437 0.006
Frequency-related variables (24 h)
 LF power, ms2 740.1 426.7 597.8 453.6 978.4 576.0 35.804  < 0.001 0.330  < 0.001 0.069  < 0.001 0.222  < 0.001#,* 0.064
 HF power, ms2 271.5 236.2 247.2 275.8 541.7 523.2 28.063  < 0.001 0.278 0.195 0.006  < 0.001 0.180  < 0.001#,* 0.054
 LF/HF ratio 3.7 2.2 3.2 1.9 2.4 1.2 10.494  < 0.001 0.126 0.001 0.037 0.012 0.021 0.001§,# 0.045
 LFnu 74.5 9.9 71.4 12.1 67.3 10.5 8.589  < 0.001 0.106 0.017 0.019 0.012 0.021 0.001§,# 0.046
 HFnu 25.5 9.8 28.6 12.1 32.7 10.4 8.521  < 0.001 0.105 0.017 0.019 0.012 0.021 0.001§,# 0.046
Non-linear variables (24 h)
 SD1, ms 32.4 43.6 57.5 130.4 29.5 21.2 2.185 0.071 0.029 0.315 0.003 0.422 0.002 0.016§,* 0.028
 SD2, ms 219.5 61.1 271.7 457.6 205.3 47.3 1.007 0.404 0.014 0.442 0.002 0.633 0.001 0.476 0.005
VAI 0.558 0.324 0.786 1.506 1.228 0.1323 7.845  < 0.001 0.097 0.084 0.010 0.211 0.005 0.001§,# 0.052
(B) Group Adjusted model Sex Age Group
PCS (n = 103) CAD (n = 103) Ctrl (n = 90) F p η2 p η2 p η2 p η2
M SD M SD M SD
Time-related variables (6 h day)
 NN interval, ms 735.0 86.7 796.8 113.2 757.1 103.6 7.165  < 0.001 0.090 0.006 0.026 0.299 0.004 0.002§,* 0.043
 SDNN, ms 124.1 32.5 121.3 43.6 92.5 21.7 15.741  < 0.001 0.178 0.019 0.019 0.010 0.023  < 0.001#,* 0.0936
 rMSSD, ms 40.2 21.2 35.1 21.5 28.8 11.3 7.338  < 0.001 0.092 0.010 0.023 0.031 0.016 0.003# 0.040
 pNN50, % 7.4 7.1 8.1 11.6 8.1 7.8 5.364  < 0.001 0.069 0.066 0.012  < 0.001 0.058 0.702 0.002
Frequency-related variables (6 h day)
 LF power, ms2 643.0 414.7 477.8 416.3 959.2 578.2 43.666  < 0.001 0.375  < 0.001 0.046  < 0.001 0.242  < 0.001#,* 0.090
 HF power, ms2 221.9 201.9 218.2 281.1 346.7 340.5 13.736 0.079 0.159 0.160 0.007  < 0.001 0.117 0.073 0.018
 LF/HF ratio 3.9 2.3 3.0 2.0 4.0 2.7 3.933  < 0.001 0.051 0.024 0.017 0.409 0.002 0.001§,* 0.051
 LFnu 75.4 9.7 69.6 13.5 75.7 9.6 5.185  < 0.001 0.067 0.187 0.006 0.995 0.000  < 0.001§,* 0.058
 HFnu 24.6 9.7 30.4 13.5 24.3 9.6 5.185  < 0.001 0.067 0.187 0.006 0.995 0.000  < 0.001§,* 0.058
(C) Group Adjusted model Sex Age Group
PCS (n = 103) CAD (n = 103) Ctrl (n = 90) F p η2 p η2 p η2 p η2
M SD M SD M SD
Time-related variables (6 h night)
 NN interval, ms 909.4 127.2 963.2 152.8 959.5 109.2 7.126  < 0.001 0.090  < 0.001 0.057 0.819 0.001  < 0.001§,# 0.056
 SDNN, ms 103.9 33.3 93.9 31.0 96.1 24.3 14.442  < 0.001 0.166  < 0.001 0.081  < 0.001 0.082 0.019§ 0.027
 rMSSD, ms 45.9 24.4 38.6 23.3 47.7 23.0 12.781  < 0.001 0.149 0.011 0.022  < 0.001 0.110 0.168 0.012
 pNN50, % 13.8 13.3 12.7 13.9 20.7 16.0 22.333  < 0.001 0.235 0.005 0.026  < 0.001 0.173 0.014# 0.029
Frequency-related variables (6 h night)
 LF power, ms2 923.0 594.2 812.2 652.1 1162.7 863.3 19.185  < 0.001 0.209  < 0.001 0.076  < 0.001 0.119 0.001#,* 0.045
 HF power, ms2 366.5 355.8 306.1 367.9 862.7 888.8 30.715  < 0.001 0.297 0.184 0.006  < 0.001 0.166  < 0.001#,* 0.077
 LF/HF ratio 3.8 2.7 3.9 3.6 1.9 1.2 10.9  < 0.001 0.13 0.059 0.012 0.006 0.0126 0.009# 0.031
 LFnu 73.5 12.4 73.3 12.5 61.3 13.4 22.188  < 0.001 0.234 0.004 0.028  < 0.001 0.058  < 0.001# 0.060
HFnu 26.5 12.4 26.7 12.5 38.7 13.4 22.113  < 0.001 0.233 0.004 0.028  < 0.001 0.058  < 0.001# 0.059

Data is presented as mean ± SD. Differences of HRV variables were analyzed using general linear model (GLM) with factors of group (PCS, CAD, control) and sex and age. Post hoc between-group comparisons were performed by one-way ANOVA and Bonferroni’s correction or Kruskal–Wallis test. PCS, Post-Covid Syndrome; CAD, Coronary Artery Disease.

§Significant for PC vs. CAD; #significant for PC vs. control; *significant for CAD vs. control (Ctrl).

Significant values are in bold.