Table 2.
Characteristics Based on ECG Spectrogram Phenotypes
| Variable | e-LFCNB absent (n = 4014) | e-LFCNB present (n = 1233) | P |
|---|---|---|---|
| Age (years) | 61.4 ± 10.8 | 64.7 ± 10.9 | < 0.001 |
| Sex (M/F) | 1811 / 2203 | 781 / 452 | < 0.001 |
| BMI (kg/m2) | 28.6 ± 5.3 | 29.3 ± 5.2 | < 0.001 |
| ESS | 7.7 ± 7.5 | 8.3 ± 8 | < 0.001 |
| Total sleep time (TST) | 355.9 ± 63.9 | 351.8 ± 61.8 | 0.10 |
| Stage 1 (% TST) | 5.4 ± 4 | 6.2 ± 4.7 | < 0.001 |
| Stage 2 (% TST) | 56.5 ± 11.8 | 59.4 ± 11.2 | < 0.001 |
| Stage 3+4 (% TST) | 18.1 ± 11.9 | 15.1 ± 11.4 | < 0.001 |
| REM (% TST) | 20 ± 6.3 | 19.3 ± 6.3 | 0.002 |
| AHI (per h of sleep) | 6.5 ± 9 | 17.6 ± 18 | < 0.001 |
| Arousal index (per h of sleep) | 17.8 ± 9.2 | 23.8 ± 13 | < 0.001 |
| CAI (per h of sleep) | 0.1 ± 0.7 | 0.9 ± 3.1 | < 0.001 |
| Sleep efficiency (%) | 81.8 ± 10.7 | 80.4 ± 10.3 | 0.002 |
| HFC* | 47.4 ± 21.6 | 33.8 ± 19.5 | < 0.001 |
| LFC* | 33 ± 17 | 49.8 ± 18.9 | < 0.001 |
| e-LFC* | 12.8 ± 11.1 | 28.8 ± 17.9 | < 0.001 |
| VLFC* | 16.7 ± 7.3 | 14.4 ± 6.6 | < 0.001 |
*
Percentage of signal detection windows with the specific cardiopulmonary coupling spectral peak in the total sleep period. BMI: body mass index; ESS: Epworth sleepiness score; AHI: apnea-hypopnea index; CAI: central apnea index; HFC: High Frequency Coupling; LFC: Low frequency coupling; e-LFC: elevated-Low Frequency Coupling; NB – narrow spectral band; VLFC: Very Low Frequency Coupling