Table 3.

Non-linear indices of heart rate variability analyzed from the databases of the 3 heart rate analysis groups obtained from the selection of 256 highest stability points and the final 5 min of the record.

	PTS group			PAS group			ARA group
	256 points	5 min	p	256 points	5 min	p	256 points	5 min	p
Non-linear methods
SD1 (ms)	11 ± 17	11 ± 17	0.97	19 ± 40	23 ± 37	0.78	29 ± 33	29 ± 32	0.95
SD2 (ms)	20 ± 12	22 ± 13	0.29	43 ± 63	50 ± 58	0.63	66 ± 39	77 ± 26	0.60
ApEn	1.00 ± 0.13	1.11 ± 0.11	<0.01*	1.00 ± 0.13	1.08 ± 0.12	0.16	1.00 ± 0.01	1.10 ± 0.11	<0.05*
SampEn	1.72 ± 0.32	1.58 ± 0.56	0.20	1.62 ± 0.56	1.38 ± 0.65	0.31	1.80 ± 0.30	1.60 ± 0.70	0.21
DFA α1	0.85 ± 0.52	0.93 ± 0.46	0.43	0.84 ± 0.60	0.83 ± 0.56	0.94	0.88 ± 0.37	1.10 ± 0.43	0.36
DFA α2	0.85 ± 0.31	0.99 ± 0.29	0.17	1.13 ± 0.40	1.05 ± 0.45	0.61	0.94 ± 0.64	1.10 ± 0.46	0.72

PTS, patients with aortic stenosis; PAS, physically active subjects; ARA, amateur running athletes; SD1, standard deviation of the points on the transverse axis of the ellipsis; SD2, standard deviation of the points on the longitudinal axis of the ellipsis; ApEn, approximate entropy; SampEn, sample entropy; DFA α1, short-term of detrended fluctuation analysis; DFA α2, long-term of detrended fluctuation analysis. Values expressed as median ± interquartile range.

^*Mann–Whitney's test (p < 0.05).