Digoxin has been an effective treatment for fetal
supraventricular tachycardia (SVT), but second-line
therapy remains more controversial. Thirty-seven cases of fetal SVT were identified that received
digoxin as first-line
therapy. Seventeen fetuses (46%) converted to and maintained normal sinus rhythm.
Flecainide was used in 13/15 patients requiring second-line
therapy; 12/13 (92%) converted to sinus rhythm. Of seven hydropic fetuses, five required second-line
therapy and were then successfully converted with
flecainide. The improved efficacy of
flecainide was statistically significant with a p value <0.01. Complete follow-up was available in 13
digoxin-treated and in 12 second-line
therapy infants. Prolonged or multiple
drug therapy for postnatal
arrhythmia management was required in 3/13 (23%) patients in the
digoxin group and in 8/12 (67%) patients requiring second-line
therapy. This demonstrated a correlation between the need for second-line
fetal therapy and more complex postnatal management with a p value of 0.003.
Digoxin remains an effective first-line
therapy in the treatment of fetal SVT.
Flecainide is an effective second-line
therapy, especially in the face of
fetal hydrops. Use of second-line
therapy in fetal SVT is a predictor of complex postnatal course, and these patients should be followed more closely.