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

OBJECTIVE: The aim of this study was to evaluate the role of amiodarone for the prenatal treatment of hydropic fetuses with supraventricular tachycardia. METHODS: A group of 26 hydropic fetuses with supraventricular tachycardia was studied retrospectively. RESULTS: Twenty-five fetuses received transplacental treatment. The overall prenatal conversion rate was 60%. Nine fetuses were converted to sinus rhythm using either flecainide (n = 7) or amiodarone (n = 2) as first line therapy, whilst digoxin alone or in association with sotalol failed to restore sinus rhythm in all cases. After first-line therapy, supraventricular tachycardia persisted in 10 fetuses. Nine fetuses received amiodarone alone or in association with digoxin as second-line therapy, five of whom were converted to sinus rhythm. Among the 11 live neonates treated by amiodarone in utero, 2 (17%) presented an elevated thyroid stimulating hormone at day 3-4. These two infants received thyroid hormone substitution therapy and had a normal outcome. CONCLUSION: When first-line therapy fails to restore sinus rhythm in hydropic fetuses with supraventricular tachycardia, amiodarone therapy should be considered as it allows a substantial number of fetuses to be converted prenatally.