Fetal tachycardia: a role for amiodarone as first- or second-line therapy?

Background: Fetal tachycardias result in serious prenatal and postnatal morbidity and mortality. Intrauterine treatment can improve prognosis dramatically and the therapeutic protocol is well defined. Currently, amiodarone is used as third-line therapy and is reserved for refractory cases.

Aims: Our aim was to review the management and outcome of fetal tachycardia, giving particular consideration to the efficacy and safety of amiodarone therapy.

Methods: This was a retrospective study of 24 consecutive cases of sustained fetal tachycardia, treated mainly with digoxin and/or amiodarone administered by the transplacental route.

Results: The 24 fetal tachycardias comprised 16 supraventricular tachycardias with 1:1 atrioventricular conduction, seven atrial flutters and one ventricular tachycardia. Seven fetuses were hydropic and eight experienced less severe cardiac failure. Digoxin monotherapy converted 5/12 non-hydropic fetuses and 0/2 hydropic fetuses, with one intrauterine death. Amiodarone monotherapy converted 5/5 fetuses, including two hydropic fetuses: one ventricular tachycardia, two atrial flutters and two supraventricular tachycardias. When administered with digoxin, amiodarone converted all but two fetuses (7/9). No deaths were associated with amiodarone, but there was moderate morbidity, with six transient elevations of thyroid stimulating hormone at birth, two of which required short-term thyroid hormonal substitution therapy.

Conclusion: Maternal oral amiodarone seems to be effective and relatively safe, even in hydropic fetuses. We suggest that this treatment could be used earlier than is currently advised.