A Case of Fulminant Infective Endocarditis in Mitral Valve Prolapse With Septic Emboli and an Annular Abscess

Mitral valve prolapse (MVP) is associated with an increased risk of infective endocarditis (IE), particularly in patients with mitral regurgitation and leaflet thickening. Historically, a subset of patients with mitral valve prolapse were considered for antibiotic prophylaxis before dental procedures. Conversely, current recommendations limit prophylaxis to the highest-risk cardiac conditions, such as congenital heart defects, mechanical valves, heart transplant with valvular issues, and a history of IE. We present a case of a 59-year-old man with a history of MVP with mildly thickened posterior leaflet, hypertension, hyperlipidemia, and prior tobacco use who presented to the hospital with nausea and vomiting four weeks after a tooth extraction. Initial laboratory evaluation was notable for elevated inflammatory markers, elevated transaminases, hyperbilirubinemia, and elevated troponin levels. Blood cultures grew methicillin-sensitive Staphylococcus aureus (MSSA). Transthoracic echocardiography demonstrated MVP with new moderate mitral regurgitation. Brain MRI showed multifocal embolic infarcts and a small subarachnoid hemorrhage. Transesophageal echocardiography (TEE) revealed vegetations involving both mitral valve leaflets, extension into the mitral annulus and left atrial wall, and annular abscess formation. The patient's hospital course was complicated by septic shock, respiratory failure, intermittent ventricular tachycardia, transient complete heart block, acute tubular necrosis, postoperative atrial fibrillation, and new-onset cardiomyopathy. He ultimately required urgent mitral valve replacement with extensive debridement of the mitral annulus and left atrial wall, followed by prolonged intravenous antibiotic therapy. Follow-up imaging showed a well-seated prosthetic valve without recurrent vegetation. This case highlights the severe complications of IE in patients with MVP and mildly thickened leaflets following dental procedures. Current guidelines do not recommend routine prophylaxis in this population. This case raises important questions regarding whether selected moderate-risk MVP patients with leaflet thickening and mitral regurgitation may benefit from individualized prophylactic strategies.