A 56-year-old woman with unknown medical history is brought to the emergency department in an unresponsive state. Paramedics were called for sudden-onset, left-sided weakness, and when they arrived at the patient's house she was having a generalized tonic-clonic seizure. Antiseizure medications were given and the patient was subsequently intubated. Evaluation shows a comatose woman with left hemiplegia. Neuroimaging reveals a large infarction in the right middle cerebral artery territory with cerebral edema. Despite aggressive interventions, the patient dies from brain herniation. Autopsy reveals multiple small, nondestructive masses attached to the edges of the mitral valve leaflets. Microscopy shows that these masses are composed of platelet-rich thrombi, but no organisms are present. Which of the following is most closely associated with this patient's heart valve findings?

Question

A 56-year-old woman with unknown medical history is brought to the emergency department in an unresponsive state.  Paramedics were called for sudden-onset, left-sided weakness, and when they arrived at the patient's house she was having a generalized tonic-clonic seizure.  Antiseizure medications were given and the patient was subsequently intubated.  Evaluation shows a comatose woman with left hemiplegia.  Neuroimaging reveals a large infarction in the right middle cerebral artery territory with cerebral edema.  Despite aggressive interventions, the patient dies from brain herniation.  Autopsy reveals multiple small, nondestructive masses attached to the edges of the mitral valve leaflets.  Microscopy shows that these masses are composed of platelet-rich thrombi, but no organisms are present.  Which of the following is most closely associated with this patient's heart valve findings?

Quizplus · Accepted Answer

The autopsy finding of sterile platelet-rich thrombi attached to the mitral valve leaflets is characteristic of nonbacterial thrombotic endocarditis (NBTE) (marantic endocarditis). The pathogenesis of NBTE is thought to begin with valvular endothelial injury caused by circulating inflammatory cytokines, which triggers platelet deposition in the presence of an underlying hypercoagulable state. NBTE is most commonly associated with advanced malignancy (especially mucinous adenocarcinoma) and systemic lupus erythematosus (Libman-Sacks endocarditis); less commonly, it can occur with antiphospholipid syndrome, disseminated intravascular coagulation, and extensive burns. Histologically, NBTE vegetations consist of bland thrombus with strands of fibrin, immune complexes, and mononuclear cells (white thrombus). The vegetations typically affect the left-sided heart valves (mitral or aortic) and are often asymptomatic; however, systemic embolization (eg, stroke, acute limb ischemia) can occur and is the most common presentation of NBTE. (Choice B) Chronic liver failure (ie, cirrhosis) can be complicated by portal vein thrombosis; however, it is not associated with NBTE. (Choice C) Dilated cardiomyopathy is characterized by ventricular enlargement and reduced systolic function. It can occasionally lead to left ventricular mural thrombus with risk of systemic embolization, but it is not associated with NBTE. (Choice D) Intravenous drug use increases the risk of bacterial endocarditis, not NBTE. Injected particulate matter (eg, dirt) is thought to cause microdamage to the right-sided heart valves before being filtered out by the lungs, facilitating bacterial attachment to primarily the tricuspid valve. (Choice E) Temporal (giant cell) arteritis, a large-vessel vasculitis that typically presents with headaches and fever, is associated with an increased risk of venous thromboembolic disease. Although associated NBTE has been reported, it is quite rare. Educational objective: Nonbacterial thrombotic endocarditis is characterized by valvular deposition of sterile platelet-rich thrombi. It likely results from valvular damage due to inflammatory cytokines in the setting of an underlying hypercoagulable state, and it is most commonly seen with advanced malignancy (especially mucinous adenocarcinoma) or systemic lupus erythematosus.

A 56-Year-Old Woman with Unknown Medical History Is Brought to the Emergency