Table 2.

Measures of heart rate variability at baseline in patients grouped by survival state

Survivors (n=204)Nonsurvivors (n=77)P
SDNN, ms95.8 (70.8–120.9)86.5 (55.9–106.1)0.007
SDANN, ms87.1 (66.9–111.4)79.8 (51.6–97.9)0.008
RMSSD, ms13.9 (10.2–18.0)13.2 (10.0–17.6)0.60
pNN50, ms0.40 (0.04–1.77)0.23 (0.02–1.63)0.65
HRVTI, ms24.3 (18.1–31.4)19.8 (15.0–27.8)0.001a
ULF, ln (ms2)8.78 (8.03–9.35)8.29 (7.64–9.00)<0.001a
VLF, ln (ms2)6.19 (5.41–6.78)5.56 (4.61–6.40)<0.001a
LF, ln (ms2)4.51 (3.71–5.35)4.02 (2.75–4.84)0.004
HF, ln (ms2)3.80 (3.08–4.46)3.69 (2.92–4.38)0.38
LF/HF1.92 (1.17–3.52)1.18 (0.82–2.26)<0.001a
Scaling exponent α11.17 (0.98–1.34)1.01 (0.77–1.15)<0.001a
Scaling exponent α21.20 (1.16–1.25)1.24 (1.18–1.29)<0.001a
HRT category, 0/1/2, n (%)b20 (29.4%)/29 (42.7%)/19 (27.9%)5 (13.5%)/12 (32.4%)/20 (54.1%)0.02
DC, ms4.33 (3.31–5.68)3.81 (2.61–4.70)<0.001a
  • Data are the median (interquartile range) unless otherwise indicated. SDNN, SD of normal-to-normal intervals during 24 hours; SDANN, SD of the averages of NN intervals in all 5-minute segments during 24 hours; RMSSD, square root of the mean square of differences between adjacent NN intervals; pNN50, percentage of the number of pairs of adjacent NN R-R intervals differing >50 ms in the total NN intervals; HRVTI, heart rate variability triangular index; ULF, ultra-low frequency (≤0.003 Hz) power; VLF, very-low frequency (0.003–0.04 Hz) power; LF, low frequency (0.04–0.15 Hz) power; HF, high frequency (0.15–0.40 Hz) power; HRT, heart rate turbulence; DC, deceleration capacity.

  • a Significant after correcting for multiple comparisons of 14 variables (P<0.003 for type 1 error level of 0.05).

  • b Data were obtained only in patients with >5 ventricular ectopic beats (per day) suitable for HRT analysis.