Is antiarrhythmic therapy safe in twin pregnancies?

The optimal treatment for foetal supraventricular tachycardia (SVT) in twin pregnancies is unclear because of the possible impact on the second twin. This review compared a foetus we treated with antiarrhythmic drugs with the previous case studies.Our case was a dichorionic diamniotic twin pregnancy, where one twin developed foetal hydrops secondary to SVT at 22 weeks of gestation. We searched PubMed to look for previous cases of SVT in twin pregnancies.Treatment with transplacental antiarrhythmic therapy from 22 to 36 weeks of gestation successfully resolved the SVT in our affected twin without any impact on the healthy twin or mother. We only found seven similar cases of SVT in twin pregnancies from 1999 to 2017. Although there was no consensus on the treatment that should be provided, none of the studies reported side effects in the twins or the mothers.Despite a lack of data on SVT in twin pregnancies, our case, and the previous cases we identified, allowed us to conclude that transplacental antiarrhythmic treatment can successfully achieve cardioversion in the affected twin. It can do this without side effects for the healthy foetus or the mother, even if the treatment lasts for a long period of time.