Second-line treatment of fetal supraventricular tachycardia using flecainide acetate.

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.