Non-bacterial thrombotic endocarditis: Manifestations and diagnosis in the age of echocardiography

Sterile vegetations of the cardiac valves were first identified in 1888 by Zeigler, with case reports described eponymously in 1924 by Libman and Sacks.1 2 These and subsequent early accounts identified an association between non-infectious endocarditis and a variety of diseases, specifically malignancy and rheumatological conditions such as systemic lupus erythematosus (SLE) and antiphospholipid antibody syndrome (AAS). Autopsy cases predominated the early literature; however, after the advent of echocardiography, many case series relied on non-invasive diagnosis (table 1).3 4 These studies found a strong association with cancers, with a higher prevalence and greater mortality in patients with metastatic disease. Up to 31 per cent of cases are in fact culture-negative endocarditis rather than non-bacterial thrombotic endocarditis (NBTE). Therefore, a diagnosis of NBTE requires obtaining extended blood cultures to ensure infection is fully excluded.5 Currently, the diagnosis remains challenging as there are no pathognomonic echocardiographic or clinical features, and because the disease is associated with a variety of concomitant disorders.