A Large Mitral Valve Vegetation Not Visualized on Transthoracic Echocardiography: A Case Report

BACKGROUND Immediate evaluation, diagnosis, and treatment of a patient with infective endocarditis, an infection of the endocardium and/or integral structures found within the heart, is essential to patient survival. CASE REPORT We present the case of a 41-year-old man who was brought to the Emergency Department for altered mental status and fever. He was found to have methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia complicated with severe respiratory failure and metabolic encephalopathy, necessitating intubation and mechanical ventilation. As part of the workup for persistent Staphylococcal bacteremia, 2 transthoracic echocardiograms (TTE) failed to reveal any valvular abnormalities. However, a transesophageal echocardiogram (TEE) detected a 30×30 mm large vegetation on the anterior mitral valve leaflet. Due to the overall size and risk of systemic embolization, and the fact that the patient developed new-onset heart failure, the mitral valve was replaced using an open approach. The patient tolerated the procedure well and was discharged after an extended period of hospitalization. CONCLUSIONS Although the literature emphasizes that the sensitivity of TTE significantly increases when the vegetation size is above 1 cm, it is of utmost importance for clinicians to keep in mind that this is not always true, and clinicians should consider performing a TEE to rule out infective endocarditis whenever a TTE is unable to detect any vegetation in a patient with persistent Staphylococcal bacteremia. This is clearly demonstrated by the present case, in which two TTEs failed to detect a 30×30 mm vegetation.