Heart Rate Variability Is Associated with Survival in Patients with Brain Metastasis: A Preliminary Report

Table 2

Time domain HRV analysis (𝑛=40).

HRV Indices	Mean	SD	Median	Lower one-third	Upper one-third
Mean NN (ms)	733.58	136.04	712.50	669.00	788.54
SDNN (ms)	14.30	7.68	15.00	10.06	17.06
RMSSD (ms)	11.65	7.88	10.50	6.53	15.06
TINN (ms)	76.65	28.41	78.00	63.00	94.00
NN50	2.45	5.34	0.00	0.00	0.00
pNN50 (%)	0.63	1.33	0.00	0.00	0.00

HRV: heart rate variability, SD: standard deviation, NN: normal-to-normal interval, SDNN: standard deviation of normal-to-normal interval, RMSSD: root mean square standard deviation of normal-to-normal interval, TINN: triangular interpolation of normal-to-normal interval histogram, NN50: number of pairs of adjacent normal-to-normal intervals differing by more than 50 ms, and pNN50: the proportion of NN50 divided by total normal-to-normal intervals.