Failure of oral anti-Xa to prevent non-bacterial thrombotic endocarditis in cancer: case report and literature review.

Background: Marantic endocarditis (ME) is a rare but potentially fatal complication of hypercoagulable states, posing a significant diagnostic challenge in oncology. Timely detection and appropriate treatment are essential to prevent complications and improve clinical outcomes. In neoplastic contexts, tumour cells can activate the coagulation cascade, leading to thromboembolic events that serve as critical warning signs. A multidisciplinary approach is vital for effective management of this condition. Case summary: A 64-year-old woman, recently diagnosed with non-small cell lung carcinoma, was receiving anticoagulation therapy with Rivaroxaban for right iliac-femoral deep vein thrombosis. She developed progressive symptoms, including visual disturbances and dyspnoea. Magnetic resonance imaging of the brain showed ischaemic lesions in the territory of the right posterior cerebral artery and a pulmonary-CT angiogram identified severe bilateral pulmonary embolism. A transoesophageal echocardiography revealed vegetation on the mitral valve, consistent with ME. Switching from Rivaroxaban to low molecular weight heparin temporarily stabilized her hypercoagulable state, but the rapid progression of her underlying malignancy led to her death within 5 months of the diagnosis. Discussion: This rare case of ME in a cancer patient, despite treatment with a direct oral anticoagulant, raises important considerations. Although cases are scarce in the literature, it highlights the complexities of anticoagulation management in oncology, suggesting that the hypercoagulable state may surpass the protective effects of these medications. This case underscores the need for enhanced cardiac monitoring and a tailored anticoagulation approach, even for patients under anticoagulant therapy. It advocates for re-evaluating follow-up protocols and anticoagulant selection in this clinical context.