T-wave morphology evaluation in healthy subjects: the effect of posture on the measurements

This study investigated the effect of posture on the T-wave morphology in healthy subjects. Standard 12-lead ECGs were digitally recorded from 70 healthy subjects. From each subject, 10 consecutive ECGs were taken in each of the supine, sitting, and standing positions. T-wave morphology indices included: the total cosine R-to-T (TCRT), normalized T-wave loop area (TLA), and relative T-wave residuum (TR). There was a trend towards a systematic change in measurements related to postural changes. TCRT significantly decreased when the position was changed from supine to sitting (p<0.05), and from sitting to standing (p<0.05). Similar pattern was found in the TLA (p<0.05). Conversely, TR increased significantly both in sitting and in standing compared to that in supine (p<0.05). It may be speculated that the increased sympathetic tone induced by postural tests leads to modifications of T-wave morphology detectable in digital ECGs