Influenza A-Induced Myocarditis and Persistent Complete Heart Block in Pregnancy

Cardiovascular implications of respiratory viruses are often overlooked. Arrhythmia is a rare manifestation of influenza A and is usually self-terminating after the acute phase. Only a handful of cases of complete heart block (CHB) associated with influenza A have been reported. We present the case of a healthy 33-year-old primigravida who developed CHB at 20 weeks' gestation after contracting influenza A, requiring hospitalisation. Thereafter, the patient remained asymptomatic throughout the prepartum period despite persisting CHB and bradycardic escape rhythm. Delivery was successfully managed with spinal anaesthesia and close haemodynamic monitoring. Postpartum cardiac imaging confirmed myocarditis. CHB with a narrow escape rhythm persisted after delivery. The emergence of symptoms and a blunted heart rate response to exercise necessitated elective permanent pacemaker (PPM) implantation after careful consideration. This case underscores the importance of cardiac evaluation in pregnancy, particularly after seasonal influenza, and highlights the challenges in diagnosing and managing CHB within this context.