EP09.69: Prenatal diagnosis of autoimmune congenital heart block and its successful management and outcome

Autoimmune congenital heart block (ACHB), a component of neonatal lupus syndrome occurs in 1- 2% of fetuses of women with positive anti-Ro/SSA and anti-La/SSB antibodies where the cardiac conduction system is damaged by immune complexes. Highest risk for injury is between 16 and 28 weeks of gestation age (GA) with a recurrence rate of 12–25% in subsequent pregnancies. 15% to 30% of affected infants succumb, while the rest require lifelong pacemaker implantation. We present a case of prenatally diagnosed ACHB and its management. 35 year old G2, a known case of systemic lupus erythematosus with strong positive SSA titre, on hydroxychloroquine (HCQ), oral prednisolone and low dose aspirin was on weekly PR interval follow-up from 16 weeks. At 23 weeks fetus showed cardiomegaly, pericardial effusion, bradycardia (FHR84 bpm), ‘a’ wave reversal and moderate ascites-suggestive of ACHB. She was started on dexamethasone/salbutamol with close monitoring. At 32 weeks, FHR was 64bpm, reduced fetal cardiac contractility with worsening pericardial effusion and ascites. Elective Caesarean section at 33 weeks delivered a female baby weighing1.68kg with HR 61 bpm. ECG showed CHB with narrow QRS waves and no anomalies by ECHO and was started on isoprenaline infusion. She was discharged at 4 weeks and is currently 6 months with HR 64 bpm, no cardiac failure and on cardiology follow up with planned pacemaker implantation when indicated. As ACHB is irreversible, weekly PR interval monitoring helps in the early identification of this problem though the transition from a normal rhythm to a third-degree atrioventricular block occurs within 24 hours, which highlights the importance of a closer surveillance of rhythm by daily ambulatory FHR monitoring performed directly by the patients. HCQ plays a vital role in reducing the prevalence of ACHB in fetuses. Low-dose IVIG/plasmapheresis does not decrease the recurrence of ACHB in high-risk pregnancies. Pacemaker implantation improves the survival rate of ACHB patients with CHB with a survival rate of 96%.