The effect of flecainide acetate on fetal heart rate variability: A case report

Fetal supraventricular tachycardia is most often treated by maternal application of digoxin. A drug used for second-choice therapy is flecainide acetate. For a case in which maternal digoxin therapy failed, flecainide caused a lowering of the fetal heart rate (FHR) but, simultaneously, variability and accelerations nearly disappeared. The fetus demonstrated a normal movement pattern. Fetal well-being during delivery was assessed by regular ultrasound observations of fetal movements. Flecainide was not continued after birth, and digoxin therapy was started when tachycardia reappeared. The heart rate changed into a reactive pattern 5 days after birth. Around that time, flecainide levels in the neonatal serum were below the limit of detection. Flecainide use can cause the absence of accelerations and poor variability in the FHR.