Introduction Autoimmune-associated congenital Long QT Syndrome (LQTS) is a rare cardiac disorder linked to maternal anti-Ro/SSA antibodies. These antibodies can cross-react with foetal cardiac ion channels, potentially leading to life-threatening arrhythmias. Thus, early diagnosis and management are crucial for improving outcomes.

Case Presentation A 39-year-old pregnant woman presented at 25 weeks’ gestation with foetal bradyarrhythmia and early hydrops. Foetal echocardiography revealed dilated ventricles, decreased systolic function, and frequent ventricular arrhythmias. Maternal testing confirmed anti-Ro-60 positivity. The patient underwent multiple treatments, including intravenous immunoglobulin, magnesium sulphate, propranolol, and hydroxychloroquine.

Result Despite interventions, persistent foetal bradycardia necessitated emergency delivery at 34 weeks. The newborn presented with syndromic features and a low heart rate, requiring resuscitation. Unfortunately, the infant succumbed to complications on day 5 of life.

Discussion This case highlights the challenges in diagnosing and managing autoimmune-associated LQTS prenatally. Foetal echocardiography is crucial in early detection, revealing characteristic signs such as bradycardia, AV block, and ventricular arrhythmias. Recent studies suggest hydroxychloroquine may reduce the risk of advanced heart block when administered early in pregnancy. However, the long half-life of hydroxychloroquine presents both advantages and limitations in treatment timing.

Conclusion Autoimmune-associated congenital LQTS remains a complex and challenging condition to diagnose and treat prenatally. Early detection through foetal echocardiography and maternal antibody screening is vital. While current treatment options show promise, further research is required to optimize management strategies and improve outcomes for affected foetuses and newborns. Thus, multidisciplinary collaboration between obstetricians, paediatric cardiologists, and rheumatologists is essential to effectively care for these high-risk pregnancies.