Clunies-Ross N, Roston TM, Taylor J, et al. - The correlation of QT interval prolongation with torsade de pointes has been observed but it has a poor predictive value for drug torsadogenicity. In patients undergoing cesarean delivery (CD), carbetocin is recommended as an uterotonic, however, there remains uncertainty concerning its effect on transmural dispersion of myocardial repolarization (TDR), which is measured as the time interval between the peak and end of the T wave (Tp-e) and is a more reliable predictor of drug torsadogenicity. Researchers here examined how carbetocin dose affects Tp-e and Bazett-corrected QT intervals (QTc) during elective CD under spinal anesthesia. They randomized 50 healthy parturients undergoing elective CD with a standardized spinal anesthetic and phenylephrine infusion to receive an intravenous (IV) bolus of carbetocin 50 µg (C50) or 100 µg (C100) via an infusion pump over 1 minute. Retrieval of a 12-lead electrocardiogram (ECG) was done at baseline, 5 minutes after spinal anesthesia, then 5 and 10 minutes after carbetocin administration. Analysis was performed on data from 41 parturients with a mean (standard deviation [SD]) age of 39.0 (0.7) years and weight of 75.0 (12.0) kg. Observations revealed no effect on Tp-e of providing C50 IV after CD in healthy parturients under spinal anesthesia, but it was minimally prolonged after providing C100. Carbetocin administration led to statistically significant increase in QTc, but with no apparent dose-dependent effect. There appeared no clinically significant impact of minimal Tp-e prolongation at the higher dose on TDR and hence the risk of inducing torsade de pointes is low.