Unusual rapid progression of non-bacterial thrombotic endocarditis in a patient with bladder cancer despite undergoing intensification treatment with rivaroxaban for acute venous thromboembolism

A 65-year-old man was referred to our department for evaluation of bilateral femoral swelling after total cystectomy and ureterostomy for advanced bladder cancer. Contrast-enhanced computed tomography detected a small pulmonary thromboembolism and a deep vein thrombus (Panels A and B). Transthoracic echocardiography showed normal mitral valve (Panel C; Supplementary material online, Video S1). The patient was pathophysiologically diagnosed with venous thromboembolism (VTE) associated with active cancer. Anticoagulant therapy with rivaroxaban was initiated at a dose of 30 mg for 3 weeks. However, 17 days after anticoagulant therapy, he presented to our hospital due to sudden onset of right lower limb paraesthesia, dysarthria, and agnosia. Brain magnetic resonance imaging showed acute sporadic infarction of left parietal lobe and subacute infarction of the left angular gyrus (Panel D). Transthoracic (Panel E; Supplementary material online, Video S2) and transoesophageal (Panel F) echocardiography at second admission demonstrated mobile and fragile vegetations (yellow arrow) ∼20 mm in diameter on the mitral valve, which was not observed 17 days before. According to urgent vegetectomy, non-bacterial vegetations were easily peeled off because the boundary between the vegetations and the mitral valve was relatively clear. Pathological images demonstrated that vegetation was composed of fibrin and red blood cells, whereas inflammatory cells and bacterial invasion were not observed (Panels G and H).