Flecainide treatment of fetal tachycardia and hydrops fetalis in a twin pregnancy

Fetal supraventricular tachycardia (SVT) is a rare complication of pregnancy leading, in some cases, to cardiac failure and intrauterine fetal death. Digoxin is a safe and successful treatment for SVT and can be considered as the first-line choice in singleton and multiple pregnancies in which one of the fetuses presents with SVT1, 2. Other well-known drugs used for this indication are flecainide3 and amiodarone. Clinical and biochemical fetal hypothyroidism has been associated with the use of amiodarone1. In a multiple pregnancy, a triplet with two healthy fetuses and one affected fetus was successfully treated with digoxin and no adverse effects were reported, neither in the mother nor in the healthy fetuses4. No cases so far have been reported describing the treatment with flecainide in a multiple gestation. A 39-year-old patient, gravida 2 para 1, was admitted with a diagnosis of fetal tachycardia in one fetus of a dichorionic, diamniotic twin pregnancy at 21 weeks' gestation. During a systematic fetal ultrasound examination, tachycardia at a rate of 210–230 bpm with fetal hydrops was detected in one of the fetuses. With M-mode evaluation of the fetal heart a diagnosis of SVT was made. An initial treatment was started with digoxin 1000 µg intravenously in four doses over 24 h. Maternal biochemical parameters and electrocardiograms were monitored. The treatment was continued for 3 days but fetal cardioversion was not achieved. The patient was then given oral flecainide, 300 mg daily divided in three doses. After 24 h the fetal heart rate was monitored and a sinus rhythm at a rate of 150 bpm was observed. The therapy was maintained until delivery and no other abnormalities of the cardiac rhythm were demonstrated. Hydrops resolved completely within 2 weeks of the cardioversion. Due to premature rupture of membranes and a breech presentation, at 31 weeks' gestation a Cesarean section was performed. No hydrops was detected and both newborns were healthy. The mother was discharged after 4 days and the neonates were followed in neonatal intensive care for 9 days. During this period, daily electrocardiograms (ECGs) were within normal limits as were subsequent ECGs performed intermittently for the first 2 years. Flecainide has been described as a highly effective medication even in hydropic fetuses, working quickly and efficiently because it crosses the placenta rapidly, reaching 80% of the maternal serum levels5. Fetal death with flecainide treatment has been reported and several concerns have been raised about the possible maternal drug-induced proarrhythmias6. We decided to administer flecainide, despite the possible serious side-effects for the fetus because we balanced this risk against the progressive cardiac insufficiency (manifested as hydrops) which would have led to intrauterine death. We did not consider administering flecainide with digoxin because of the high inotropic effect of the latter and the possible myocardial hypoxia, although successful treatment with digoxin and flecainide has been described in a single fetus affected at 13 weeks of gestation7. To our knowledge this is the first case describing the effective treatment with flecainide alone of a single hydropic fetus with SVT in a twin pregnancy. S. Gerli*, G. Clerici*, A. Mattei*, G. C.