STABILITY OF INDEX OF HEART-RATE-VARIABILITY IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Stability of indexes of heart rate variability (HRV) has not been esta blished for patients with congestive heart failure (CHF). We therefore measured Holter-derived HRV indexes in 17 stable patients with class II or III CHF (mean age 52 +/- 9 yr; 5 men and 12 women) on two occasi ons 2 weeks apart. Stability was determined via paired t tests and int raclass correlation coefficients (ICCs). ICCs for time domain indexes of HRV were greater than or equal to 0.86 for 24 hours, greater than o r equal to 0.73 for daytime, and greater than or equal to 0.72 for nig httime indexes reflecting longer-term variability. After log transform ation, ICCs for the short-term 24-hour measures PNN50 (percentage of N -N intervals >50 msec different from preceding interval) and RMSSD (th e root mean square of successive differences) were 0.85 and 0.67. ICCs for frequency domain indexes of HRV were 0.86 to 0.91. We compared HR V indexes, serum norepinephrine (NE) levels, and respiratory sinus arr hythmia induced by paced breathing, also considered measures of;autono mic tone. NE correlated weakly with average R-R interval, and all inde xes of HRV reflecting longer-term variation (r = -0.32 to r = -0.50). ICC was 0.78 for NE. Respiratory sinus arrhythmia was highly repeatabl e (ICC = 0.70) but did not correlate significantly with NE or any meas ure of HRV. We conclude that time and frequency domain indexes of HRV are stable over time in CHF patients without intervening events.