From the Guidelines
Marantic endocarditis, also known as non-bacterial thrombotic endocarditis (NBTE), is a condition characterized by sterile vegetations composed of fibrin and platelets that form on heart valves, typically occurring in patients with advanced malignancy, chronic inflammatory states, or hypercoagulable conditions. This condition is associated with numerous diseases, including cancer, connective tissue disorders, autoimmune disorders, and hypercoagulable states, as noted in the 2015 ESC guidelines for the management of infective endocarditis 1. The vegetations in NBTE are usually small, broad-based, and irregularly shaped, with little inflammatory reaction at the site of attachment, making them more friable and detachable, which can lead to systemic embolization and potentially life-threatening complications.
Key Characteristics of NBTE
- Sterile vegetations composed of fibrin and platelets on heart valves
- Associated with hypercoagulable states, cancer, and chronic inflammatory conditions
- Valvular vegetations are usually small, broad-based, and irregularly shaped
- Can cause systemic embolization, leading to strokes, kidney infarcts, or limb ischemia
Diagnosis and Treatment
The diagnosis of NBTE relies on strong clinical suspicion, the presence of a heart murmur, and evidence of multiple systemic emboli, as well as the presence of vegetations not responding to antibiotic treatment, as recommended in the 2015 ESC guidelines 1. Transesophageal echocardiography (TOE) should be ordered when there is a high suspicion of NBTE, particularly if there is a new murmur or a change in a pre-existing murmur in the setting of a predisposing disease. Treatment focuses on addressing the underlying condition and anticoagulation, typically with heparin followed by warfarin or direct oral anticoagulants, to prevent further thromboembolic complications, as suggested by the American College of Chest Physicians evidence-based clinical practice guidelines 1.
Prognosis and Management
The prognosis of NBTE depends largely on the underlying disease, with cancer-associated marantic endocarditis generally carrying a poor prognosis unless the malignancy can be effectively treated. Comprehensive haematological and coagulation studies should be performed to search for a potential cause, and multiple blood cultures should be undertaken to rule out infective endocarditis, although negative blood cultures do not exclude the diagnosis of NBTE, as noted in the 2015 ESC guidelines 1. Early diagnosis and treatment of NBTE are crucial to improve prognosis and prevent further thromboembolic complications.
From the Research
Definition and Characteristics
- Marantic (non-bacterial thrombotic) endocarditis, also known as non-bacterial thrombotic endocarditis (NBTE), is a rare form of noninfectious endocarditis presenting with thromboembolism, including ischemic cerebral stroke 2, 3, 4, 5, 6.
- It is characterized by the deposition of thrombi and fibrin on normal or degenerated cardiac valves in the absence of microorganisms 3.
- NBTE is mostly associated with advanced malignancy and characterized by the presence of sterile vegetation on heart valves 2.
Diagnosis
- The diagnosis is usually based on vegetations seen on an echocardiogram, with negative blood cultures suggesting a noninfectious etiology 2.
- Laboratory tests and blood cultures should be taken in the work-up to differentiate with an infectious endocarditis 5.
- Advanced imaging techniques, such as fluorodeoxyglucose-positron emission tomography (FDG-PET) scan, may be needed to diagnose NBTE 4.
Clinical Manifestations and Treatment
- Clinical manifestations are a result of multifocal systemic embolisms in brain, spleen, kidney, skin, or extremities 5.
- Therapy includes anticoagulation with low molecular weight heparin or non-vitamin K antagonists, treating the underlying disease, and surgical intervention 5, 6.
- Early diagnosis and prompt management are critical to reduce the complications of NBTE and improve the patients' quality of life 2.