Is digoxin still justifiable as single first-line therapy in fetal SVT associated with fetal hydrops?

As long as there is no unanimity in the approach to the drug treatment of fetal tachycardia, digoxin continues to be the most commonly used first-line antiarrhythmic drug. Flecainide, sotalol and amiodarone have emerged as effective second-line treatment after digoxin failure both in nonhydropic and hydropic fetuses.

We report five consecutive cases with fetal tachyarrhythmias complicated by hydrops diagnosed and treated in our center between 25 and 28 weeks of gestation (2002–2007). Four fetuses were started on transplacental digoxin whereas one fetus was treated with flecainide alone. The latter resulted in successful and stable cardioversion. Digoxin as a single first-line treatment failed in all four cases, even in two patients showing severe drug induced side effects correlating with high maternal plasma digoxin levels.

One fetus died after the mother refused all further treatment for tachycardia refractory to therapy with sotalol and amiodarone. The other three digoxin treated fetuses converted to sinus rhythm after receiving amiodarone as second- or third-line therapy (one after failure of sotalol and the other after flecainide).

We conclude that digoxin as a single first-line treatment is ineffective and precious time may be lost in gaining control of the tachyarrhythmias associated with hydrops. In our opinion further studies need to address the role of amiodarone as a first-line treatment.