Non-bacterial thrombotic endocarditis overview

# Overview

# Historical Perspective
The association between thromboembotic events and malignancy was made by Armand Trousseau in the year 1865. In 1926, Dr. Benjamin Sacks and Dr. Emmanuel Libman published cases of "valvular masses" that were examined clinically and during autopsies and found to be free of all microorganisms. These masses were initially named "indeterminate endocarditis".

# Classification
According to Allen and Sirota,  Non-bacterial thrombotic endocarditis may be classified according to morphology into 5 subtypes.

# Pathophysiology
Although the exact pathogenesis of non-bacterial thrombotic endocarditis is not completely understood, endothelial injury correlated with a hypercoagulable state has been implicated. Pathogenesis can be sub-sectioned into four factors thought to be involved in instigating NBTE. These include; Immune complexes, Hypoxia , Hypercoagulability, andCarcinomatosis. Conditions associated with nonbacterial thrombotic endocarditis include; Malignancies, Systemic autoimmune diseases (SLE is the most common,Hypercoagulable states, Chronic inflammatory states, Heart failure with valvulopathy, e.t.c.

# Differentiating non-bacterial thrombotic endocarditis from other Diseases
Non-bacterial thrombotic endocarditis must be differentiated from other diseases that cause a new or changed heart murmur, multiple systemic emboli, +/-fever, such as infective endocarditis, degenerative valvular disease, and pulmonary infarction.

# Epidemiology and Demographics
Non-bacterial thrombotic endocarditis is a rare autopsy finding. Although the exact incidence of NBTE is unknown, it is thought to be approximately 900-600 per 100,000 individuals worldwide. The prevalence of NBTE is approximately 9,300 per 100,000 individuals worldwide. Patients of all age groups may develop NBTE, usually in the 4th to 8th decade. There is no racial predilection to NBTE, and NBTE affects men and women equally.

# Risk Factors
The most potent risk factor in the development of non-bacterial thrombotic endocarditis is advanced malignancy. Other risk factors include systemic lupus erythematosus, antiphospholipid syndrome, and chronic inflammatory states.

# Screening
There is insufficient evidence to recommend routine screening for non-bacterial thrombotic endocarditis.

# Natural History, Complications, and Prognosis
Non-bacterial thrombotic endocarditis is an asymptomatic condition that can present acutely with recurrent thromboembolism. Prognosis is generally poor, as the disease is associated with advanced cancers, autoimmune diseases and recurrent thromboembolism.

# Diagnosis

## Diagnostic Study of Choice
There is no single diagnostic study of choice for the diagnosis of non-bacterial thrombotic endocarditis.

## History and Symptoms
The majority of patients with non-bacterial thrombotic endocarditis are asymptomatic. Systemic embolism of the brain, liver, or spleen is a common initial clinical manifestation of NBTE, and occur in more than half of patients. Patients with NBTE may have a positive history of malignancy, disseminated intravascular coagulation, antiphospholipid syndrome, autoimmune disease such as systemic lupus erythematosus, e.t.c

## Physical Examination
There are no specific physical exam findings for non-bacterial thrombotic endocarditis. Patients with NBTE may show signs of systemic thromboembolism, cardiac dysfunction, and underlying diseases.

## Laboratory Findings
There are no specific diagnostic laboratory findings associated with non-bacterial thrombotic endocarditis. Tests are usually conducted to detect the underlying cause of NBTE and differentiate it from infective endocarditis.

## X-ray
There are no x-ray findings associated with non-bacterial thrombotic endocarditis. However, a chest x-ray may be helpful in the diagnosis of complications of NBTE, which include, cardiomegaly pulmonary congestion, pleural effusion, and calcifications due to the lesions.

## Echocardiography and Ultrasound
Echocardiography may be helpful in the diagnosis of non-bacterial thrombotic endocarditis. It is especially important in visualizing valvular vegetations suggestive of NBTE. The vegetations in NBTE are typically <1cm, broad-based, and irregularly shaped. 75% of vegetations affect the mitral valves and less commonly have been found to involve all the cardiac valves.

## Other Imaging Findings
Whole-body CT or MRI may be helpful in the diagnosis of non-bacterial thrombotic endocarditis. It may show evidence of systemic embolism in patients with undetermined NBTE.

## Other Diagnostic Studies
There are no other diagnostic studies associated with non-bacterial thrombotic endocarditis.

# Treatment

## Medical Therapy
There is no treatment for non-bacterial thrombotic endocarditis; the mainstay of therapy is the identification and treatment of the underlying condition, with an aim to reduce the risk of systemic embolism. Unless there is a specific contraindication, anti-coagulation with IV unfractionated heparin or subcutaneous low molecular weight heparin is recommended in all patients with a clinical diagnosis of NBTE.

## Interventions
There are no recommended therapeutic interventions for the management of non-bacterial thrombotic endocarditis

## Surgery
Surgery is not the first-line treatment option for patients with non-bacterial thrombotic endocarditis and is usually reserved for patients with either heart failure, acute valve rupture, or recurrence of thromboembolism despite adequate anticoagulation. It is important to weigh the risks associated with the patient's underlying condition with the benefits of surgery.

## Primary Prevention
There are no established measures for the primary prevention of non-bacterial thrombotic endocarditis.

## Secondary Prevention