Nonbacterial thrombotic endocarditis associated with chronic hypoxia and secondary polycythemia

Abstract

A 72-year-old man with a past medical history significant for chronic obstructive pulmonary disease (COPD), witnessed nocturnal apnea and persistent 80-pack-year tobacco use presented with a new-onset of aphasia. MRI brain demonstrated restricted perfusion in the left temporoparietal area and insular cortex, consistent with subacute embolic strokes. Investigation for the etiology was notable for secondary polycythemia and non-specific mitral valve thickening on transthoracic echocardiography (TTE). Subsequent transesophageal echocardiography (TEE) showed a heterogenous,1.1 cm mass on the anterior mitral valve leaflet. Following warfarin bridge therapy, surgical resection revealed a sterile thrombus, consistent with nonbacterial thrombotic endocarditis (NBTE). Chronic hypoxia has been implicated in the pathogenesis of NBTE in both human and animal studies. While animal models have suggested a direct causal relationship, human studies are largely limited to isolated case reports, which have almost uniformly been confounded by the presence of other disorders of hypercoaguability, such as malignancy or disseminated intravascular coagulation (DIC). Unique in comparison to prior studies, this report demonstrates a case of NBTE in the setting of chronic oxygen deprivation and secondary polycythemia in a patient without any additional major risk factors.