Abstract 4372568: Medical Management Triumph: Spontaneous Resolution of a Large Native Valve Vegetation in a Case of Pediatric Infective Endocarditis

Introduction: Native valve endocarditis (NVE) is rare in children, particularly in structurally normal hearts. Vegetations >10 mm pose a high embolic risk and often prompt surgical evaluation. We report a rare pediatric case where a large mitral valve vegetation resolved completely with medical therapy alone. Case Presentation: A previously healthy 6-year-old girl from a rural, socioeconomically disadvantaged background presented with a 2-week history of persistent high-grade fever, fatigue, and poor oral intake. She had no prior cardiac or chronic illnesses. Initial management for presumed enteric fever was unsuccessful. On admission, she was febrile (38.5°C), tachycardic (110 bpm), normotensive (90/70 mmHg), and had a grade III/VI pansystolic murmur. The rest of the exam was unremarkable. Labs showed leukocytosis (WBC 17,500/μL) with neutrophilia and elevated inflammatory markers. Chest X-ray and abdominal ultrasound were normal. Transthoracic echocardiography (TTE) revealed a mobile 11 mm vegetation on the anterior mitral leaflet with severe mitral regurgitation (Figure 1). Blood cultures grew methicillin-resistant Staphylococcus aureus (MRSA). IV vancomycin and gentamicin were initiated. No anticoagulation was given. Cranial CT and neurologic assessment were normal. After 14 days, repeat TTE showed a reduction in vegetation size to 8 mm. She remained afebrile and clinically improved. Antibiotics were continued for 6 weeks. A follow-up echo 4 weeks post-discharge showed complete resolution of the vegetation with persistent moderate mitral regurgitation (Figure 2). No embolic or neurologic events occurred. At 3-year follow-up, TTE confirmed no vegetation recurrence and stable MR (Figure 3) . Discussion: This case demonstrates that even large vegetations in pediatric NVE can resolve fully with antibiotics alone in clinically stable patients. While surgical intervention is often considered for vegetations >10 mm, this case supports a tailored, conservative approach with close echocardiographic follow-up, especially where access to surgery may be limited.