Objectives: We reviewed our institution's experience with isolated (congenital) third-degree atrioventricular block (CAVB) to identify pre- and post-natal predictors of mortality and the requirement for pacemakers in infancy and childhood.
Background: Because of the relative rarity of the disease, there is a paucity of data concerning the outcome of fetuses and children with isolated CAVB.
Methods: The medical records of all cases of CAVB encountered at our institution from January 1965 to December 1998 were analyzed.
Results: Of 102 cases identified, 29 were diagnosed in utero (F) at 26.1 +/- 5.6 weeks gestation, 33 as neonates (N; < or = 28 days), and 40 as children (C) at 5.7 +/- 4.8 years of age. Anti-Ro and/or anti-La were present in 95% of F and 90% of N, but only in 5% of C mothers tested (p < 0.0001). Patients with CAVB having F, N and C diagnosis had a mortality of 43%, 6% and 0%, respectively, in the first two decades of life. Increased mortality risk was associated with a fetal diagnosis of CAVB (13/15 deaths; p < 0.05), fetal hydrops (6/6 cases; p < 0.0001), endocardial fibroelastosis (5/5 cases; p < 0.0001) and delivery at < or = 32 weeks (4/6 cases; p < 0.05). Timing of pacemaker implantation differed significantly among F versus N (p < 0.05) and N versus C (p < 0.001) cases. At 20 years of age only 11% and 12% of CAVB patients with N and C diagnosis, respectively, were not paced.
Conclusions: Pre-natal diagnosis of CAVB is associated with high fetal and neonatal mortality. Among survivors, whether the diagnosis is made before or after birth, most undergo pacemaker implantation by adulthood, with earlier intervention and a significantly greater need for reintervention among those diagnosed in utero.