Nonbacterial Thrombotic Endocarditis: Key Points

The following are key points to remember from a state-of-the-art review on nonbacterial thrombotic endocarditis:

1. Nonbacterial thrombotic endocarditis (NBTE), previously known as marantic endocarditis, is a rare condition characterized by the formation of sterile vegetations on the surface of heart valves.
2. Epidemiology: NBTE occurs most commonly in association with malignancies and autoimmune conditions (predominantly antiphospholipid antibody syndrome [APLS] or systemic lupus erythematosus; less commonly rheumatoid arthritis or other vasculopathies). In addition, NBTE has been reported in association with COVID-19; and in association with burns, sepsis, and indwelling catheters.
3. Pathogenesis: The exact pathogenesis of NBTE is unknown. However, an interplay between endothelial injury, hypercoagulability, hypoxia, and immune complex deposition appears to be responsible for the formation of sterile valvular vegetations in NBTE.
4. Clinical presentation: The most common presentation of NBTE is with an embolic event, with cerebral embolic events occurring more commonly than peripheral thromboembolic events. The finding of a cardiac murmur is uncommon.
5. Diagnosis: The diagnosis of NBTE is challenging.
   1. Diagnosis requires a high degree of suspicion in patients at risk who present with stroke, multifocal arterial thromboembolism, acute coronary syndrome, or a finding of cardiac vegetations in the absence of symptoms.
   2. Patients with NBTE should undergo a thorough evaluation to exclude an underlying etiology such as an occult malignancy or autoimmune disorder.
   3. Imaging with transthoracic echocardiography (TTE) is favored for initial screening, but transesophageal echocardiography should be used if TTE is nondiagnostic.
   4. Surveys suggest that most patients with NBTE present with involvement of a single valve (most commonly the mitral valve followed by the aortic valve), with a minority of patients presenting with multi-valvular involvement.
   5. Distinguishing NBTE and culture-negative infective endocarditis can be challenging, with an accurate diagnosis relying more on clinical presentation and laboratory and microscopic data than on echocardiographic vegetation characteristics.
6. Management: The management of NBTE predominantly involves anticoagulation and treatment of the underlying malignant or autoimmune condition responsible for the prothrombotic state.
7. Anticoagulation: With limited data available specific to patients with NBTE, the choice of anticoagulant predominantly is influenced by the underlying condition. 
   1. Warfarin is the preferred anticoagulant among patients with thrombotic APLS. Although low molecular weight heparin has been preferentially used for venous thromboembolism prophylaxis among patients with cancer, recent guidelines have endorsed the use of direct oral anticoagulants (DOACs). There are reports of DOAC failures in patients with NBTE in the settings of cancer or COVID-19.
   2. The duration of anticoagulation should take into consideration the status of the underlying disease, the presence of valvular lesions follow-up imaging, and an individualized assessment of risks and benefits.
8. Surgery: There is a limited role for surgical intervention in patients with NBTE, typically in the settings of heart failure, recurrent embolic events despite medical therapy, or rarely for acute valve rupture.
9. Prognosis: The prognosis of patients with NBTE is poor, especially among patients with cancer in whom NBTE heralds an advanced stage of disease
   
   
   

https://academic.oup.com/eurheartj/advance-article-abstract/doi/10.1093/eurheartj/ehae788/7905393