Prenatal diagnosis of complete atrioventricular block associated with structural heart disease: combined experience of two tertiary care centers and review of the literature.

OBJECTIVE: To review the pattern of presentation, management and outcome of fetal complete atrioventricular block (CAVB) associated with major structural congenital heart disease (CHD), when compared to isolated CAVB.

METHODS: Retrospective analysis of the medical records and echocardiograms of all CAVB cases, diagnosed prenatally at two tertiary care centers between the years 1990 and 2002.

RESULTS: Of a total of 59 consecutive fetal cases of CAVB, 24 (41%) had underlying major CHD, mainly left isomerism (n = 18) and congenitally corrected transposition of the great arteries (cc-TGA) (n = 3). When compared to isolated CAVB (n = 35), cases with CHD were detected earlier (21 +/- 6 vs. 26 +/- 6 weeks; P < 0.02) and-despite comparable heart rates-more often had fetal hydrops (38% vs. 9%; P < 0.02), while pregnancy continuation (66% vs. 94%; P < 0.02) or prenatal treatment (19% vs. 64%; P < 0.001) was less likely. Of 16 CHD cases with pregnancy continuation, beta-inotropic treatment of fetal bradycardia was attempted in three cases: all had left isomerism and died early postnatally. Livebirth and 1-year survival rates of CAVB with CHD were 56% and 19%, respectively, when compared to isolated CAVB with 88% and 75%, respectively (P < 0.0001). The four neonatal survivors (one left isomerism, three cc-TGA) had heart rates persistently > 60 bpm throughout gestation and 3/4 underwent a biventricular repair.

CONCLUSIONS: Fetal CAVB with CHD continues to be associated with a poor outcome, in particular in the presence of left isomerism and fetal heart rates < 60 bpm.