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Table 2 Area under the curve (AUC), cut off values and their sensitivity and specificity, and 95% confidence intervals (95% CI) for the use of RMSSD as discriminatory variable to distinguish atrial fibrillation from sinus rhythm in 14 warmblood horses

From: Can heart rate variability parameters derived by a heart rate monitor differentiate between atrial fibrillation and sinus rhythm?

Pace

Method

Artifact correction

AUC

cut off

sens

spec

 

95% CI

 

95% CI

Rest

ECGMan

none

0.99

215

1

0.77–1

1

0.77–1

Rest

ECGAut

none

0.96

383

0.93

0.66–1

0.93

0.66–1

Rest

ECGAut

1

1

188

1

0.77–1

1

0.77–1

Rest

ECGAut

2

0.99

131

1

0.66–1

0.93

0.66–1

Rest

ECGAut

3

0.94

111

1

0.77–1

0.93

0.66–1

Rest

ECGAut

4

0.77

65

0.93

0.66–1

0.69

0.42–0.92

Rest

ECGAut

5

0.37

24

0,5

0.23–0.77

0.38

0.13–0.65

Rest

HRMElec

Polar Flow

0.93

136

0.86

0.57–0.98

0.86

0.57–0.98

Walk

ECGMan

none

0.97

121

0.93

0.66–1

0.93

0.66–1

Walk

ECGAut

none

0.96

164

0.93

0.66–1

0,86

0.57–0.98

Walk

ECGAut

1

1

119

1

0.77–1

1

0.77–1

Walk

ECGAut

2

1

111

1

0.77–1

1

0.77–1

Walk

ECGAut

3

1

92

1

0.77–1

1

0.77–1

Walk

ECGAut

4

0.99

57

1

0.77–1

0.93

0.66–1

Walk

ECGAut

5

0.74

22

0.78

0.49–0.95

0.57

0.29–0.82

Walk

HRMElec

Polar Flow

0.97

70

0.93

0.66–1

0.93

0.66–1

Trot

ECGMan

none

1

36

1

0.77–1

1

0.77–1

Trot

ECGAut

none

0.77

90

0.86

0.57–0.98

0.72

0.42–0.91

Trot

ECGAut

1

1

51

1

0.77–1

0.93

0.66–1

Trot

ECGAut

2

1

42

1

0.77–1

0.93

0.66–1

Trot

ECGAut

3

1

40

1

0.77–1

1

0.77–1

Trot

ECGAut

4

1

33

1

0.77–1

1

0.77–1

Trot

ECGAut

5

0.93

15

0.93

0.66–1

0.93

0.66–1

Trot

HRMElec

Polar Flow

1

21

1

0.77–1

1

0.77–1

  1. Two-minute recordings at rest, walk and trot were analyzed using 4 different methods of RR detection and HRV analysis. The automatically analyzed ECG followed by beat-to-beat manual correction of QRS detection (ECGMan) with HRV analysis using Kubios HRV Software was considered the gold standard method. HRM Polar heart rate monitor (Equine H7) with plastic electrodes and Polar Flow Software. ECGAut ECG with automatic RR interval detection (Televet 100) and Kubios HRV software with 5 different artifact correction levels. The artifact correction algorithm identifies every RR interval that differs from the average RR interval of the 2-min recording more than a specified threshold value as artifacts and replaces the corrupted RR interval by interpolated RR values. The threshold values used in this study were 0.45 s (very low artifact correction), 0.35 s (low), 0.25 s (moderate), 0.15 s (high) and 0.05 s (very high)