Table 2.
Changes in time domain HRV indices of the study population before and after ivabradine treatment
| Variable | Before treatment | After treatment | Change. % |
|---|---|---|---|
| HR, bpm | 83.6 ± 6.0 | 64.6 ± 5.8† | - 33.3 |
| RR interval, ms | 713 ± 74 | 943 ± 101† | + 34.1 |
| SDNN, ms | 56.2 ± 15.7 | 87.9 ± 19.4† | + 58.5 |
| SDANN, ms | 49.5 ± 14.7 | 76.4 ± 19.5† | + 56.3 |
| SDNN index, ms | 24.7 ± 8.8 | 38.3 ± 13.1† | + 55.3 |
| RMSSD, ms | 13.5 ± 4.6 | 17.8 ± 5.4† | + 35.2 |
| pNN50, % | 2.4 ± 1.6 | 3.2 ± 2.2† | + 43.3 |
†
p < 0.0001 between before and after treatment
bpm: beats per min; HR: mean heart rate; HRV: heart rate variability; pNN50: percentage of successive normal RR intervals exceeding 50 ms; RMSSD: the square root of the mean of the squares of the differences between successive normal-to-normal RR intervals; RR: mean RR interval; SDANN: the standard deviation of 5-min mean RR intervals; SDNN: the standard deviation of all normal-to-normal RR intervals; SDNN index: the mean of the standard deviation of all normal to normal RR intervals for all 5-min segments.