Table 3: Mortality Risk Associated with Various Heart Rate Variability Measurements Using Ambulatory ECG.
| Study Name | Number of Patients | Monitoring Method | HRV parameters | Conclusions |
|---|---|---|---|---|
| Tsuji et al. 1994[10] (Framingham) | 736 | 2-hour ambulatory ECG | VLFP, LFP, HFP, LFP/HFP, TP, SDNN, rMSSD, pNN50+ | lnLF <1 SD from mean had increased all-cause mortality (HR 1.70, 95 % CI [1.37–2.09]) |
| Tsuji et al. 1996[11] (Framingham Offspring) | 2,501 | 2-hour ambulatory ECG | VLFP, LFP, HFP, LFP/HFP, TP, SDNN, rMSSD, pNN50+ | All HRV parameters except LFP/HFP associated with increased risk of cardiac events (p=0.016–0.0496); adjusted HR for lnSDNN <1 SD from mean 1.45 (95 % CI [1.13–1.85], p=0.003) |
| Kikuya et al. 2000[12] | 1,542 | Ambulatory blood pressure monitor | SDNN | Patients in lowest tertile have increased risk of all-cause mortality (HR 3.70, p=0.003) |
| La Rovere et al. 1998[13] ATRAMI trial | 1,284 | 24-hour Holter monitor | SDNN | SDNN <70 ms had increased risk of CV-related death (RR 5.3, 95 % CI [2.49–11.4], p<0.0001) compared to >105 ms |
| Klieger et al. 1987[14] | 808 | 24-hour Holter monitor | SDNN | SDNN <50ms had increased risk of all-cause mortality compared with >100 ms (34 % versus 9 %, p <0.0001, RR 5.3) |
| Zuanetti et al. 1996[15] GISSI-2 trial | 567 | 24-hour Holter monitor | SDNN, rMSSD, NN50+ | Risk of all-cause mortality elevated for NN50+ <200, SDNN <70 ms, or rMSSD <17.5 ms (RR 2.8–3.5) |
| Adamson et al. 2004[18] | 288 | CRT-P | SDAAM | Elevated risk of all-cause mortality for SDAAM < 50 ms (HR 3.20, p=0.02) |
| Sherazi et al. 2015[19] MADIT-CRT trial | 719 | CRT-D | SDNN, SDANN, SDNNIX, rMSSD, VLF, LF, HF, LF/HF | SDNN <93ms associated with increased all-cause mortality (HR 2.10, 95 % CI [1.14–3.87], p=0.017) |
| Nolan et al. 1998[17] UK-Heart trial | 433 | 24-hour Holter monitor | SDNN, rMSSD, sNN50 | SDNN <93ms has all-cause mortality RR 1.62 (95 % CI [1.16–2.44]) |
CRT-D = cardiac resynchronisation therapy defibrillator; CRT-P = cardiac resynchronisation therapy pacemaker; HF = high frequency power; HRV = heart rate variability; LF = low frequency power; LF/HF = low frequency to high frequency power ratio; ln HF = natural log of the high-frequency measurement; pNN50 = percentage of RR intervals that differ by 50ms; rMSSD = root mean square of the differences in successive R-R intervals; SD = standard deviation; SDAAM = SD of 5 min median A-A intervals; SDANN = SD of 5 min R-R intervals; SDNN = standard deviation of NN intervals; SDNNIX = mean SD of all R-R intervals; TP = total power; VLF = very low frequency power.