Table 2

The short term reproducibility (coefficient of variance %) of QT dispersion and conventional ECG measurements (study A)

SupineSittingStandingInspirationExpiration
Global QT dispersion19.6 (10.9)20.6 (12.4) 28.2 (17.8)2-150 23.3 (11.9)2-150 20.0 (12.1)
Precordial QT dispersion28.1 (13.4)32.3 (17.7) 43.8 (29.8)2-150 32.5 (21.6)2-150 31.5 (17.2)
Global QT-SD15.6 (8.7)17.8 (11.9) 24.9 (17.6)2-150 20.2 (10.6)2-150 17.0 (10.3)
Precordial QT-SD23.4 (11.6)28.2 (17.5) 39.7 (31.1)2-150 28.6 (20.9)2-150 27.2 (15.6)
Heart rate3.5 (1.3)4.4 (1.9)2-150 4.9 (2.2)2-150 4.1 (2.1)2-150 3.7 (1.5)
PR interval2.5 (1.3)2.7 (1.3)2-150 3.4 (5.6)5.3 (8.7)2-150 3.5 (5.3)
QRS duration2.9 (1.6)3.1 (1.5)3.2 (1.6)4.0 (1.9)2-150 3.3 (1.3)
QT interval1.5 (1.0)1.8 (1.4)2-150 2.0 (1.0)2-150 2.1 (1.3)2-150 1.7 (1.1)2-150
QTc interval1.4 (0.7)1.9 (0.9)2-150 1.9 (1.0)2-150 2.0 (1.1)2-150 1.8 (0.9)2-150
  • Values are mean (SD).

  • 2-150 p < 0.05 v supine; p < 0.05 v mean values between recordings in sitting and standing, or between inspiration and expiration.

  • QT-SD = QT standard deviation.