The Impact of Posture on Cardiac Repolarization: More Than Heart Rate?

Abstract

We have demonstrated a postural effect on cardiac repolarization independent of heart rate using two individualized correction methods, as well as QTc-F and QTc-LR, and the bin method. Characterization of postural differences in QT/QTc (other than QTc-B) may provide a safe and inexpensive physiological control to validate the ECG methodology used in clinical trials to assess potential drug-induced QT interval changes.

Effect of brivaracetam on cardiac repolarisation – a thorough QT study

“…The average QTc SS profiles at baseline ( Figure 2) were similar in the four treatment groups, with a minimum value observed at 6 h post-dose which could be described as a post-prandial shortening 16 . Pre-dose QT and QTc SS were similar among groups ( Table 1).…”

Clinical impact of repolarization changes in supine versus upright body position

“…Additionally, in comparison to previous, smaller studies [2,4,5], additional parameters were added that have not, as yet, been assessed in this context. These variables are of crucial impact for the accurate assessment and treatment of a patient in cases of an emergency or in long-term follow-up.…”

“…It was hypothesized that this potential could even be large enough to mask or mimic signs of ischemia in the ECG. Furthermore, few prospective studies, with only 12, 40 and 54 subjects respectively [2,4,5], investigated the effect of postural change in body position on QT and QTc interval. However, all these data were gained either from geometric models or only small cohorts.…”

“…A standard ECG is routinely recorded in the supine position [1]. The electrocardiac polarization is detected from the body surface and it is an established fact that positional changes of the heart with a constant position of the ECG leads and frequently leads to alterations of various ECG findings assessed in the supine position [2].…”

Use of Continuous ECG for Improvements in Assessing the Standing Response as a Positive Control for QT Prolongation

“…1 Most correction factors do not account for this hysteresis and thus can error in their estimation of the corrected QT value depending on the timing of the measurement during heart rate acceleration or deceleration. 6,7 Other factors complicating the assessment of the QT/QTc interval changes include the individual and type of correction factor used, 8 the disease state of the subject, 4 the baseline conditions used (fully supine vs semirecumbent), 9 and changes in the T-wave morphology 10 to name a few. 6,7 Other factors complicating the assessment of the QT/QTc interval changes include the individual and type of correction factor used, 8 the disease state of the subject, 4 the baseline conditions used (fully supine vs semirecumbent), 9 and changes in the T-wave morphology 10 to name a few.…”