Prolongation of the QTc interval has been associated with cardiac dysrhythmias and sudden death. QTc dispersion (interlead variability in QTc interval) has recently been proposed as being a more sensitive marker of repolarisation abnormalities and shown to be a more specific index of arrhythmia risk. Although hypoxaemia and fenoterol have previously been shown to prolong the QTc interval, this does not reflect regional myocardial repolarisation abnormalities.
Kiely, D. G., Cargill, R. I., Grove, A., Struthers, A. D., & Lipworth, B. J. (1995). Abnormal myocardial repolarisation in response to hypoxaemia and fenoterol. Thorax, 50(10), 1062-6. https://doi.org/10.1136/thx.50.10.1062