Table 4.
Time and frequency domain parameters of short-term heart rate variability in MSA-P and MSA-C subgroups
| Short-term heart rate variability | MSA-P (n1=22) | MSA-C (n2=23) | Test statistic | P |
|---|---|---|---|---|
| SDNN (ms)$ | 14.09 (8.54) | 16.59 (13.03) | 195 | 0.188 |
| RMSSD (ms)$ | 8.7 (9.12) | 11.9 (10.07) | 180 | 0.097 |
| NN50 (count)$ | 0.001 (2) | 0.001 (1) | 243 | 0.78 |
| pNN50 (%)$ | 0.001 (0.58) | 0.001 (0.29) | 246 | 0.85 |
| Total power (ms2)$ | 183.78 (250) | 255.61 (384.1) | 202 | 0.24 |
| HF power (ms2)$ | 26.03 (38.7) | 29.67 (123.93) | 203 | 0.25 |
| LF power (ms2)$ | 26.59 (46.77) | 48.49 (79.72) | 147 | 0.016* |
| LF/HF ratio$ | 1.25 (1.53) | 1.76 (2.44) | 218 | 0.42 |
MSA=multiple system atrophy; MSA-P=parkinsonian variant; MSA-C=cerebellar variant; SDNN=standard deviation of RR Intervals; RMSSD=square root of the mean of the sum of squares of differences between adjacent RR intervals; NN50=Count of number of pairs of RR intervals differing by >50 ms; pNN50 (%) = percentage of count of number of pairs of adjacent RR intervals differing by more than 50 ms; HF power=high-frequency power; LF power=low-frequency power; LF/HF ratio=sympathovagal balance; IQR=interquartile range. $Mann-Whitney U-test, values expressed as median (IQR). *P<0.05