Isolated Atrioventricular Block in the Fetus: A Retrospective, Multinational, Multicenter Study of 175 Patients

Background— Isolated complete atrioventricular block in the fetus is a rare but potentially lethal condition in which the effect of steroid treatment on outcome is unclear. The objective of this work was to study risk factors associated with death and the influence of steroid treatment on outcome. Methods and Results— We studied 175 fetuses diagnosed with second- or third-degree atrioventricular block (2000–2007) retrospectively in a multinational, multicenter setting. In 80% of 162 pregnancies with documented antibody status, atrioventricular block was associated with maternal anti-Ro/SSA antibodies. Sixty-seven cases (38%) were treated with fluorinated corticosteroids for a median of 10 weeks (1–21 weeks). Ninety-one percent were alive at birth, and survival in the neonatal period was 93%, similar in steroid-treated and untreated fetuses, regardless of degree of block and/or presence of anti-Ro/SSA. Variables associated with death were gestational age <20 weeks, ventricular rate ⩽50 bpm, fetal hydrops, and impaired left ventricular function at diagnosis. The presence of ≥1 of these variables was associated with a 10-fold increase in mortality before birth and a 6-fold increase in the neonatal period independently of treatment. Except for a lower gestational age at diagnosis in treated than untreated (23.4±2.9 versus 24.9±4.9 weeks; P=0.02), risk factors were distributed equally between treatment groups. Two-thirds of survivors had a pacemaker by 1 year of age; 8 children developed cardiomyopathy. Conclusions— Risk factors associated with a poor outcome were gestation <20 weeks, ventricular rate ⩽50 bpm, hydrops, and impaired left ventricular function. No significant effect of treatment with fluorinated corticosteroids was seen.