Table 2.

Pearson Correlations Among the Traditional HRV Indices in the WHAS-I and Framingham

	VLF	LF	HF	SDNN	pNN50	RMSSD
VLF
LF	.69 (.85)
HF	.48 (.61)	.84 (.77)
SDNN	.78 (.86)	.80 (.75)	.75 (.63)
pNN50	.49 (.47)	.64 (.57)	.77 (.87)	.78 (.53)
RMSSD	.39 (.48)	.72 (.60)	.91 (.93)	.79 (.54)	.84 (.94)

Note: Correlations for Framingham [reported in Tsuji (19)] are given in parentheses. HRV = heart rate variability; WHAS-I = Women's Health and Aging Study-I; VLF = very low frequency; LF = low frequency; HF = high frequency; SDNN = standard deviation of N-N intervals; pNN50 = proportion of all N-N intervals that are larger than 50 ms; RMSSD = root-mean-squared differences of successive N-N intervals.