Analysis of epidemiological characteristics and psychopsychological factors of arrhythmia in the elderly

Table 4 Comparison of heart rate variability among groups, mean ± SD

Characteristic	Group A (n = 56)	Group B (n = 59)	Group C (n = 47)	Group D (n = 20)	F	P value
rMSSD (millisecond)	21.46 ± 3.51	21.52 ± 3.40	20.97 ± 3.50	36.78 ± 6.92	85.61	< 0.0001
pNM50 (%)	15.98 ± 2.28	16.10 ± 2.62	15.93 ± 2.24	22.04 ± 1.88	38.25	< 0.0001
SDNN (millisecond)	85.85 ± 12.54	84.82 ± 13.87	84.25 ± 12.16	102.8 ± 8.78	11.62	< 0.0001
SDANN (millisecond)	80.18 ± 11.40	79.69 ± 12.03	80.47 ± 12.17	90.32 ± 5.77	4.575	0.004

rMSSD: Root-mean-square of successive normal sinus two adjacent R waves (RR) interval difference; pNN50: The percentage of successive normal sinus RR intervals > 50 milliseconds; SDNN: Standard deviation of all normal sinus RR intervals over 24 hours; SDANN: Standard deviation of the average RR intervals measured every 5 minutes during the 24 hours.