Long-term outcome in fetuses with cardiac arrhythmias

The objectives of this follow-up study of 292 fetuses with various cardiac arrhythmias were to estimate the incidence of structural heart defects and fetal compromise, to investigate the effects of antiarrhythmic medication, and to evaluate perinatal mortality and morbidity and long-term outcome.

The arrhythmias were classified into atrial extrasystoles (n = 200), atrial tachycardias (n = 35), atrioventricular block (n = 36), sinus bradycardia (n = 14), and ventricular extrasystoles (n = 7), and outcome of the infants was analyzed.

The incidence of cardiac anomalies was 12% in the study population. In utero cardiac failure was noted in 11%. Among fetuses with atrial extrasystoles, 1% developed supraventricular tachycardia after birth. During antiarrhythmic therapy, sinus rhythm was achieved in 92% of nonhydropic and in 63% of hydropic fetuses. The latter had higher mortality and risk for neurologic morbidity than did nonhydropic fetuses; 38% versus 3.7% and 40% versus 12%, respectively. Among fetuses with atrioventricular block only, the survival rate was 82%, with a heart defect, prognosis was poor: 50% survived. Sinus bradycardia and ventricular extrasystoles were associated with survival rates of 75% and 67%. In the follow-up of the whole study population lasting a median 5 years, 93% are alive and 3% have a neurologic disorder.

All fetal arrhythmias except atrial extrasystoles were associated with a moderately high risk for fetal distress. In cases of compromise, fetal and neonatal prognosis was poor and was an indication for perinatal medication. After the newborn period, the prognosis has been good. However, the risk for neurologic morbidity must be taken into consideration.