Furthermore, some controversy exists in relation to first-line and second-line treatment regimens for fetal supraventricular tachycardia. In general, digoxin is used as first-line treatment in the US, whereas in Europe flecainide is used for this purpose. For second-line treatment of drug-refractory supraventricular tachycardia with hydrops fetalis, Parilla and colleagues advocate early use of fetal intramuscular digoxin.