Nonbacterial Thrombotic Endocarditis Due to Primary Gallbladder Malignancy with Recurrent Stroke Despite Anticoagulation: Case Report and Literature Review

Nonbacterial thrombotic endocarditis (NBTE) associated with malignancy is rare; its infrequency and similarity to other diagnoses make it a significant diagnostic challenge. A 63-year-old woman on rivaroxaban for prior deep vein thrombosis presented with left upper extremity weakness and left facial droop with imaging demonstrating multiple strokes. Echocardiograms revealed mitral and aortic valve vegetations. The patient was switched to apixaban and started on vancomycin and ceftriaxone for presumed culture-negative endocarditis. Despite continuing apixaban, her hospital course was complicated by new acute embolic infarcts. Workup confirmed non-mucinous metastatic biliary adenocarcinoma. The patient was placed on a heparin drip then switched to low molecular weight heparin without further embolic events and was discharged to a rehabilitation facility in stable condition with plans for chemotherapy as an outpatient. These clinical, imaging, and histologic findings were consistent with a rare case of NBTE associated with primary non-mucinous gallbladder malignancy complicated by recurrent strokes in which direct oral anticoagulants did not provide adequate anticoagulation.