Prediction of adverse cardiac events in emergency department patients with chest pain using machine learning for variable selection

Table 4 Measurements of HRV parameters and clinical signs of recruited patients

	No MACE within 72 h (N = 673)	MACE within 72 h (N = 29)	p
Clinical signs
Glasgow Coma Scale	15 (15 to 15)	15 (15 to 15)	0.001
Temperature (°C)	36.4 (0.6)	36.4 (0.5)	0.871
Pulse rate (beats/minute)	79 (17)	86 (15)	0.008
Respiratory rate (breaths/minute)	18 (3)	20 (5)	0.010
Systolic BP (mmHg)	142 (28)	124 (31)	0.001
Diastolic BP (mmHg)	77 (15)	67 (17)	0.001
Oxygen saturation (%)	98 (4)	97 (4)	0.469
Pain score	2 (0 to 4)	3 (0 to 5)	0.358
HRV parameters
aRR (s)	0.831 (0.171)	0.723 (0.139)	0.001
STD (s)	0.038 (0.028)	0.034 (0.020)	0.657
avHR (beats/minute)	75.545 (15.862)	86.122 (15.927)	0.001
sdHR (beats/minute)	3.618 (2.735)	4.328 (2.886)	0.099
RMSSD (s)	0.037 (0.039)	0.039 (0.307)	0.376
pNN50 (%)	7.294 (12.617)	7.978 (9.695)	0.198
NN50 (count)	23 (41)	31 (44)	0.220
Triangular index	3.009 (1.233)	2.481 (0.969)	0.025
TINN	0.134 (0.086)	0.105 (0.069)	0.086
LF power (ms²)	0.128 (0.074)	0.106 (0.092)	0.024
HF power (ms²)	0.125 (0.075)	0.139 (0.080)	0.303
Total power (ms²)	0.489 (0.110)	0.434 (0.177)	0.054
LF power norm (n.u.)	51.173 (20.535)	40.947 (22.966)	0.020
HF power norm (n.u.)	48.827 (20.535)	59.053 (22.996)	0.020
LF/HF	1.641 (1.869)	1.018 (0.910)	0.021

Data are shown as mean (standard deviation) or median (interquartile range, 25^th to 75^th percentiles). The p-values are calculated from the Mann–Whitney test.
MACE: major adverse cardiac events; For HRV parameters, refer to Table 1.