Table 2. All 24 features described, and the previous works in which they were used.
| Feature (Unit) | Description |
|---|---|
| RMSSD (ms) | Root mean square of Successive Differences; see [21, 22, 27] |
| HRV Mean (ms) | Mean value of RR-Intervals; see [21, 23] |
| RR-Interval variation (%) | Standard deviation divided by mean of RR-Intervals; see [24, 25] |
| Minimum (ms) | Shortest RR-Interval |
| Maximum (ms) | Longest RR-Interval |
| Difference (ms) | Longest RR-Interval—Shortest RR-Interval |
| Mean (mV) | Mean of the ECG signal |
| Skewness | Skewness of the ECG signal; see [26] |
| Kurtosis | Kurtosis of the ECG signal; see [26] |
| SDNN (ms) | Standard deviation of normal RR-Intervals; see [22] |
| Sex* | Gender of the subject |
| Age* (Years) | Age of the subject |
| Ventricular rate* (BPM) | Calculated through time between R-peaks |
| Atrial rate* (BPM) | Calculated through time between P-waves |
| QRS Duration* (ms) | Duration of QRS-Complex; see [23] |
| QT Interval* (ms) | Duration of QT-Interval; see [28] |
| QT Corrected* (ms) | Duration of corrected QT-Interval; see [29] |
| R Axis Deviation* (degree) | Right axis deviation in the direction of depolarization |
| T Axis Deviation* (degree) | T-Wave Axis Deviation indicating abnormal repolarization [29] |
| QRS Count* | Number of QRS-Complexes |
| Q Onset* (samples) | Onset of Q-Wave; see [28] |
| Q Offset* (samples) | Offset of Q-Wave |
| T Offset* (samples) | Offset of T-Wave; see [28] |
Features marked with * originate from Zheng et al. [15]