Table 2. Performance Parameters for all Patients and the Four Subgroups According to the SDNN Quartiles a, b.
| All Patients (n = 57) | SDNN-1 (n = 15) | SDNN-2 (n = 14) | SDNN-3 (n = 14) | SDNN-4 (n = 14) | SDNN quart. 2-4 (n = 42) | P Value | |
|---|---|---|---|---|---|---|---|
| Ejection Fraction, % | 28.8 ± 6.5 | 27.7 ± 7.7 | 26.0 ± 6.2 | 29.8 ± 6.3 | 30.2 ± 7.3 | 28.7 ± 6.8 | ns (0.6150) |
| Peak-VO2, mL/kg/min | 14.9 ± 4.6 | 11.4 ± 3.8 | 16.0 ± 4.6 | 16.2 ± 4.2 | 16.1 ± 4.4 | 16.1 ± 4.3 | < 0.0005 (0.0004) |
| Watt-max, watt | 69.1 ± 23.8 | 55.0 ± 23.8 | 71.4 ± 22.7 | 72.6 ± 22.9 | 59.8 ± 28.9 | 67.2 ± 25.2 | ns (0.1075) |
| Initial 6MWT, m | 366.3 ± 126.2 | 325.7 ± 63.6 | 357.4 ± 142.3 | 377.2 ± 157.7 | 400.0 ± 141.2 | 381.6 ± 142.6 | ns (0.1496) |
| Final 6MWT, m | 437.5 ± 123.1 | 348.2 ± 118.3 | 473.8 ± 74.2 | 472.8 ± 144.5 | 466.3 ± 112.7 | 469.9 ± 109.3 | < 0.0005 (0.0006) |
| Δ-6MWT, m | 70.96 ± 74.29 | 51.2 ± 47.8 | 116.8 ± 95.8 | 95.6 ± 99.0 | 65.3 ± 55.1 | 88.3 ± 81.6 | ns (0.1035) |
a Abbreviations: SDNN, standard deviation of all normal RR intervals; SDNN-1, SDNN-2, SDNN-3, SDNN-4: groups of patients stratified according to the SDNN quartiles; peak-VO2, oxygen consumption at the peak of exercise; Watt-max: peak exercise capacity in Watt; 6MWT, six-minute walking test; Δ-6MWT, difference between initial and final 6MWT; p, level of significance in student t-test for unpaired samples between patients in SDNN quartile 1 vs. patients in other quartiles of SDNN.
b data are presented as Mean ± SD.