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Table 1 List of traditional heart rate variability (HRV) and novel heart rate n-variability (HRnV) parameters used in this study. HRnV is a new representation of beat-to-beat variation in ECGs and parameter “n” controls the formation of new RR-intervals that are used for parameter calculation. Details of HRnV definition can be found in [28]

From: Utilizing machine learning dimensionality reduction for risk stratification of chest pain patients in the emergency department

HRV HR2V HR2V1 HR3V HR3V1 HR3V2
Mean NN HR2V Mean NN HR2V1 Mean NN HR3V Mean NN HR3V1 Mean NN HR3V2 Mean NN
SDNN HR2V SDNN HR2V1 SDNN HR3V SDNN HR3V1 SDNN HR3V2 SDNN
RMSSD HR2V RMSSD HR2V1 RMSSD HR3V RMSSD HR3V1 RMSSD HR3V2 RMSSD
Skewness HR2V Skewness HR2V1 Skewness HR3V Skewness HR3V1 Skewness HR3V2 Skewness
Kurtosis HR2V Kurtosis HR2V1 Kurtosis HR3V Kurtosis HR3V1 Kurtosis HR3V2 Kurtosis
Triangular index HR2V Triangular index HR2V1 Triangular index HR3V Triangular index HR3V1 Triangular index HR3V2 Triangular index
NN50 HR2V NN50 HR2V1 NN50 HR3V NN50 HR3V1 NN50 HR3V2 NN50
pNN50 HR2V pNN50 HR2V1 pNN50 HR3V pNN50 HR3V1 pNN50 HR3V2 pNN50
HR2V NN50n HR2V1 NN50n HR3V NN50n HR3V1 NN50n HR3V2 NN50n
HR2V pNN50n HR2V1 pNN50n HR3V pNN50n HR3V1 pNN50n HR3V2 pNN50n
Total powera HR2V Total power HR2V1 Total power HR3V Total power HR3V1 Total power HR3V2 Total power
VLF power HR2V VLF power HR2V1 VLF power HR3V VLF power HR3V1 VLF power HR3V2 VLF power
LF power HR2V LF power HR2V1 LF power HR3V LF power HR3V1 LF power HR3V2 LF power
HF power HR2V HF power HR2V1 HF power HR3V HF power HR3V1 HF power HR3V2 HF power
LF power norm HR2V LF power norm HR2V1 LF power norm HR3V LF power norm HR3V1 LF power norm HR3V2 LF power norm
HF power norm HR2V HF power norm HR2V1 HF power norm HR3V HF power norm HR3V1 HF power norm HR3V2 HF power norm
LF/HF HR2V LF/HF HR2V1 LF/HF HR3V LF/HF HR3V1 LF/HF HR3V2 LF/HF
Poincaré SD1 HR2V Poincaré SD1 HR2V1 Poincaré SD1 HR3V Poincaré SD1 HR3V1 Poincaré SD1 HR3V2 Poincaré SD1
Poincaré SD2 HR2V Poincaré SD2 HR2V1 Poincaré SD2 HR3V Poincaré SD2 HR3V1 Poincaré SD2 HR3V2 Poincaré SD2
Poincaré SD1/SD2 ratio HR2V Poincaré SD1/SD2 HR2V1 Poincaré SD1/SD2 HR3V Poincaré SD1/SD2 HR3V1 Poincaré SD1/SD2 HR3V2 Poincaré SD1/SD2
SampEn HR2V SampEn HR2V1 SampEn HR3V SampEn HR3V1 SampEn HR3V2 SampEn
ApEn HR2V ApEn HR2V1 ApEn HR3V ApEn HR3V1 ApEn HR3V2 ApEn
DFA, α1 HR2V DFA, α1 HR2V1 DFA, α1 HR3V DFA, α1 HR3V1 DFA, α1 HR3V2 DFA, α1
DFA, α2 HR2V DFA, α2 HR2V1 DFA, α2 HR3V DFA, α2 HR3V1 DFA, α2 HR3V2 DFA, α2
  1. Mean NN average of R-R intervals, SDNN standard deviation of R-R intervals, RMSSD square root of the mean squared differences between R-R intervals, NN50 the number of times that the absolute difference between 2 successive R-R intervals exceeds 50 ms pNN50, NN50 divided by the total number of R-R intervals, NN50n the number of times that the absolute difference between 2 successive RRnI/RRnIm sequences exceeds 50 × n ms, pNN50n NN50n divided by the total number of RRnI/RRnIm sequences, VLF very low frequency, LF low frequency, HF high frequency, SD standard deviation, SampEn sample entropy, ApEn approximate entropy, DFA detrended fluctuation analysis
  2. aIn frequency domain analysis, the power of spectral components is the area below the relevant frequencies presented in absolute units (square milliseconds)