Weighting coefficients of the original variables

VariablesPC1PC2
MRR0.250.60
SDNN0.230.91
RMSSD0.370.89
pNN500.480.79
LF–0.93–0.35
HF0.930.35
LF/HFNormlog–0.92–0.36

Where MRR is the mean of the normal sinus (NN) intervals; SDNN is the standard deviation of all NN intervals; RMSSD is the root mean square of the successive differences between adjacent NN intervals; pNN50 is the percentage of times that the change in consecutive normal sinus intervals exceeded 50 ms; LF is low frequency; HF is high frequency, and LF/HFNormlog is normalized LF/HF by logarithmic transformation. The scores are latent factors or eigenvectors of factor analysis