Biventricular mural vegetations without valvular involvement: an unusual presentation of Staphylococcus aureus endocarditis

Summary

A 42-year-old intravenous drug user presented with seizures and septicaemia. CT and MRI were suggestive of multiple brain and systemic emboli, and blood and CSF cultures were positive for Staphylococcus aureus. Initial transthoracic echocardiogram did not show any abnormalities but subsequent transoesophageal echocardiography showed two masses in the left and the right ventricle. The LV mass was large, irregular, non-mobile and attached to the basal anterolateral LV segment abutting but not involving the mitral valve. (Fig. 1). The RV mass was smaller and mobile and appeared attached to the primary chordae of anterior tricuspid valve leaflet, not encroaching the valve or affecting its function (Fig. 2). Once commenced on antibiotic treatment the patient’s condition improved, and there were no further embolic events. There was no valvular damage and sequential echo studies showed significant reduction in vegetation size. Although the formal echocardiographic definition of vegetation includes non-oscillating masses on any endocardial surface (1), primary mural endocarditis without valvular involvement is considered extremely rare (2). The diagnosis is supported by the septic and embolic clinical picture but requires awareness of this uncommon presentation. The present case is even more unusual in view of the biventricular mural localisation of the vegetations, a pattern that has been mentioned in only very few case reports (3, 4).