Table 3.
QT Dispersion Measured by Three Different Modes of Lead Selection Every Fourth Hour over 24‐Hours
| Inclusion Period | N | Qtdisp 12 Ms | Qtdisp 6 Ms | Qtdisp 2 Ms |
|---|---|---|---|---|
| Healthy subjects | 54 | |||
| 0400–0500 | 43.24 ± (17.76) | 37.69 ± (17.59) | 14.24 ± (21.42) | |
| 0800–0900 | 35.63 ± (15.64) | 28.63 ± (15.22) | 15.50 ± (16.27) | |
| 1200–1300 | 31.99 ± (14.81) | 25.73 ± (13.50) | 13.44 ± (13.77) | |
| 1600–1700 | 33.19 ± (15.97) | 26.13 ± (15.13) | 13.11 ± (14.46) | |
| 2000–2100 | 33.55 ± (16.49) | 25.42 ± (15.41) | 13.23 ± (13.16) | |
| 0000—0100 | 35.87 ± (15.62) | 30.31 ± (15.35) | 12.91 ± (19.05) | |
| Circadian variation | ||||
| P‐value | <0.0001 | <0.0001 | NS | |
| Patients with coronary artery disease | 29 | |||
| 0400–0500 | 40.37 ± (18.11) | 33.81 ± (18.92) | 20.87 ± (19.99) | |
| 0800–0900 | 40.77 ± (19.04) | 32.58 ± (18.90) | 20.98 ± (16.32) | |
| 1200–1300 | 34.23 ± (16.60) | 24.25 ± (14.14) | 17.04 ± (14.98) | |
| 1600–1700 | 36.35 ± (15.83) | 25.31 ± (14.80) | 19.40 ± (18.88) | |
| 2000–2100 | 34.98 ± (17.29) | 24.79 ± (14.60) | 16.74 ± (13.80) | |
| 0000–0100 | 40.49 ± (18.97) | 31.54 ± (17.52) | 22.40 ± (19.57) | |
| Circadian variation | ||||
| P‐value | <0.01 | <0.0001 | NS | |
| Patients with heart failure | 29 | |||
| 0400–0500 | 50.97 ± (20.36) | 37.72 ± (20.60) | 24.74 ± (17.12) | |
| 0800–0900 | 52.02 ± (21.38) | 38.93 ± (20.07) | 28.76 ± (17.75) | |
| 1200–1300 | 46.80 ± (19.20) | 34.30 ± (16.35) | 27.51 ± (16.75) | |
| 1600–1700 | 49.56 ± (19.45) | 37.87 ± (18.07) | 28.13 ± (17.77) | |
| 2000–2100 | 49.00 ± (18.95) | 35.95 ± (17.67) | 29.49 ± (16.93) | |
| 0000–0100 | 51.50 ± (19.61) | 38.90 ± (18.07) | 28.15 ± (18.20) | |
| Circadian variation | ||||
| P‐value | NS | NS | NS | |
Time‐specific mean values ± (SD) and P‐values of mixed models analysis for circadian variation are presented.
QTdisp 12 = All leads included.
QTdisp 6 = Only precordial leads included.
QT disp 2 = One pair of preselected leads included.