High specificity electrocardiogram patterns for parvovirus B19 myocarditis in children: bridging electrocardiogram findings to aetiological diagnosis.

Introduction: Parvovirus B19 (PVB19) myocarditis is a life-threatening condition with high morbidity and mortality in children. While electrocardiograms are commonly used in the early assessment of myocarditis, no specific electrocardiogram pattern has been consistently linked to PVB19. The objective of this study is to identify a distinctive electrocardiogram pattern associated with PVB19 myocarditis and evaluate its diagnostic accuracy.

Methods: This retrospective case-control study included 77 paediatric patients diagnosed with acute myocarditis at a single centre in Barcelona over 16 years (August 2008-September 2024). Twenty patients had PVB19 myocarditis, confirmed by polymerase chain reaction in blood or endomyocardial biopsy, while 57 patients had myocarditis caused by other viruses. Electrocardiogram were assessed by three cardiologists blinded to the aetiological diagnosis.

Results: A specific electrocardiogram pattern in the limb leads, characterised by peaked P waves, low QRS complex voltages, and altered repolarisation (manifesting as negative or flat T waves, with or without QTc prolongation), was observed in 14 of 20 patients (70%) with PVB19 myocarditis. Two additional patients exhibited low voltages and altered repolarisation without peaked P waves, and all demonstrated repolarisation abnormalities. In contrast, only 1 of 57 patients with myocarditis from other viruses exhibited the full electrocardiogram pattern. The pattern demonstrated a specificity of 98% and a sensitivity of 70% for PVB19 myocarditis.

Conclusion: The identified electrocardiogram pattern shows strong diagnostic specificity for PVB19 myocarditis in paediatric patients and may serve as a useful early diagnostic tool. Further multicentre studies are needed to confirm these findings and explore their clinical implications.