Fetal Bradyarrhythmia Associated With Congenital Heart Defects　– Nationwide Survey in Japan –

BACKGROUND: Because there is limited information on fetal bradyarrhythmia associated with congenital heart defects (CHD), we investigated its prognosis and risk factors. METHODS AND RESULTS: In our previous nationwide survey of fetal bradyarrhythmia from 2002 to 2008, 38 fetuses had associated CHD. Detailed clinical data were collected from secondary questionnaires on 29 fetuses from 18 institutions, and were analyzed. The 29 fetuses included 22 with isomerism, 4 with corrected transposition of the great arteries (TGA) and 3 with critical pulmonary stenosis; 14 had complete atrioventricular block (AVB), 8 had second-degree AVB, and 16 had sick sinus syndrome; 5 died before birth, and 10 died after birth (5 in the neonatal period). Neonatal and overall survival rates for fetal bradyarrhythmia with CHD were 66% and 48%, respectively. Pacemaker implantation was needed in 17 cases (89%). Beta-sympathomimetics were administered in utero in 13 cases and were effective in 6, but were not associated with prognosis. All cases of corrected TGA or ventricular rate ≥70 beats/min survived. A ventricular rate <55 beats/min had significant effects on fetal myocardial dysfunction (P=0.02) and fetal hydrops (P=0.04), resulting in high mortality. CONCLUSIONS: The prognosis of fetal bradyarrhythmia with CHD is still poor. The type of CHD, fetal myocardial dysfunction, and fetal hydrops were associated with a poor prognosis, depending on the ventricular rate.