Effects of Prophylactic Oxytocin or Carbetocin on Troponin Release and Postpartum Haemorrhage at Planned Caesarean Delivery: A Double-Blind Randomised Controlled Trial.

Abstract

Oxytocin may cause dose-dependent myocardial side effects. We investigated if carbetocin, a long-acting oxytocin analogue, causes similar changes. Double-blind randomised trial. University Hospitals, Oslo, Norway. 240 singleton pregnant women, 18-50 years, undergoing planned caesarean delivery. Participants, randomised 1:1, received oxytocin 2.5 IU or carbetocin 100 μg intravenously immediately after delivery. The primary endpoint was change from baseline in cardiac troponin I (cTnI) serum concentration at 6-10 h postpartum. Secondary endpoints included blood loss, uterine tone (numerical rating scale 0-10), rescue treatment, and healthcare costs 48 h postpartum. 215 patients underwent a planned caesarean delivery and received their allocated study drug (oxytocin group, n = 112; carbetocin group, n = 103). We detected no difference in median change from baseline cTnI concentration at 6-10 h postpartum (0.0 [95% CI -1.09 to 1.09] ng/L; p = 1.00). Median (interquartile range [IQR]) estimated blood loss was similar: oxytocin, 395 (96 to 627) mL; carbetocin, 335 (127 to 570) mL (group difference: -41 mL [95% CI -158 to 76]; p = 0.49). Rescue treatment utilisation was higher with oxytocin (46.4%) versus carbetocin (27.2%); risk difference. (-19.2% [95% CI -31.2 to -6.3]; p = 0.004). Median (IQR) uterine tone at 5 min after delivery was lower with oxytocin (7 [6 to 8]) versus carbetocin (8 [7 to 9]; group difference 1.0 NRS [95% CI 1.0 to 1.0]; p < 0.001). Despite carbetocin costing 10 times more than oxytocin, mean total healthcare costs were similar, adjusted group difference 31 NOK ($3 USD; €3; [95% CI -361 to 298 NOK]; p = 0.85). Ischaemic myocardial risk and healthcare costs were comparable for both drugs. Patients receiving carbetocin maintained better uterine tone and required fewer rescue treatments. EudraCT: 2014-000507-27; ClinicalTrials.gov Identifier: NCT03899961 (02/04/2019).