Authored by Viren Ahluwalia
Marantic endocarditis (MAE), “verrucous” or “Libman Sachs Endocarditis” are all different synonyms of the nowadays agreed term non-bacterial thrombotic endocarditis (NBTE), which is defined as fibrinous sterile valvular vegetations in the absence of infective endocarditis. MAE is associated with an autoimmunemediated inflammatory and thrombotic pathogenesis, but not with an infective pathogen. It is seen in conditions such as antiphospholipid syndrome and systemic lupus erythematosus (SLE), but also in terminal malignancies. The incidence of MAE is largely unknown. Small scale post mortem examinations reported NBTE to range between 0.9 to 1.6 % [1]. This report aims to review current literature around MAE including presentation, diagnosis and management. MAE is most commonly associated with malignancy with numerous MAE case reports in the literature ranging from pancreatic cancer to adenocarcinoma of the lungs. Overall, adenocarcinomas have been shown to be mostly associated with MAE and of those mucin-secreting and pancreatic adenocarcinoma have the highest association [2,3]. It also has a well-documented association with systemic lupus erythematosus (SLE) and is associated with greater overall mortality in such patients [4]. Other associations include autoimmune disorders, hyper coagulate states, septicemia, severe burns, or chronic disease like tuberculosis, uremia or AIDS. The trigger for MAE and how it relates to commonly associated conditions is not well understood. The potential underlying pathophysiology might include endothelial injury in the setting of hypercoagulability [5]. This endothelial damage would then lead to primary and secondary clotting cascade activation involving platelets, clotting factors and inflammatory mediators leading thrombi formation and ‘vegetation’ on affected valves. It has a greater propensity to affect left sided valves.
MAE most commonly presents initially as a consequence of its distal embolic sequalae; Common complications include cerebrovascular events, such as strokes or transient ischemic attacks [6]. Emboli can ultimately affect any arterial system including critical limb ischaemia, splenic and renal infarcts and acute mesenteric ischaemia [3]. Localisation of causation can be linked to symptoms related to underlying aetiology. In patients with malignancy there maybe systemic constitutional symptoms including weight loss, night sweats and loss of appetite. Patients with SLE may describe a history of rashes, arthralgia and renal impairment, whilst those with antiphospholipid syndrome may describe recurrent deep vein thromboses or miscarriages.
Valvular vegetations in MAE are usually small, broad based and irregular shaped. Left sided (mitral more than aortic) and bilateral vegetations are more likely to represent MAE, than infective endocarditis (see picture). MAE are rarely associated with destructive changes to the heart valve. There is no definitive investigation in diagnosing MAE, with the key principle differential diagnosis being infective endocarditis. All patients should have a full work up including routine bloods to assess for organ dysfunction and serial blood cultures. Specific antibody (antiphospholipid antibodies) and auto-immune screen should be performed to rule autoimmune conditions such as SLE. As with conventional infective endocarditis imaging is crucial in proving MAE, with transesophageal echocardiography having much greater sensitivity over transthoracic [7] in demonstrating vegetations.
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