Carbetocin has been in clinical use in EU for some years and the efficacy is documented in
several RCTs. Circulatory adverse events leading to death has been reported after intravenous
injection of oxytocin. Some studies indicate that oxytocin may lead to dose dependent
ischemic ECG changes, prolongation of QT time and liberation of biomarkers of myocardial cell
death. Previously the investigators have demonstrated comparable vasodilatory effects of
oxytocin and carbetocin. There is no clinical study comparing the specific myocardial effects
of oxytocin with carbetocin. It may have great impact on the choice of standard medication if
the cardiotoxicity of carbetocin is lower compared with oxytocin. The study of potential
cardiotoxicity has to be performed in healthy women. Knowing that millions of laboring women
have had uneventful injections of oxytocin and carbetocin after delivery, there is probably
no reason to fear long lasting negative effects of either drug. If there are differences in
cardiotoxicity, this new information should be taken into consideration when planning
delivery in pregnant women with heart disease.