Pregnancy outcome after gestational exposure to amiodarone in Canada

OBJECTIVE: Our purpose was to quantitate the risk of perinatal thyroid dysfunction and other amiodarone-induced adverse effects among infants exposed in utero to amiodarone. STUDY DESIGN: A historic cohort study of gestational exposure to amiodarone was conducted by contacting Canadian cardiac electrophysiologists. RESULTS: Twelve cases were identified. Of six with first-trimester exposure, one child had congenital mystagmus with synchronous head titubation. There was one case each of transient neonatal hypothyroidism (9%) and hyperthyroidism (9%). A fourth child, exposed to amiodarone from 20 weeks' gestation, had developmental delay, hypotonia, hypertelorism, and micrognathia. Four small-for-gestational-age infants were also exposed to β-blockers, which in addition to maternal cardiac disease, have been recognized to cause grown restriction. β-Blockers may also have contributed to bradycardia in one of the three fetuses in whom this was observed. CONCLUSIONS: Gestational exposure to amiodarone may be complicated by perinatal hypothyroidism or hyperthyroidism and possibly neurologic abnormalities, intrauterine growth retardtion or fetal bradycardia. Concomitant β-blocker therapy should probably be avoided. Full neonatal thyroid function tests and developmental follow-up are recommended.