Apixaban for the treatment of cancer-associated venous thromboembolism and left atrial appendage thrombus refractory to optimal anticoagulation with warfarin: a case report

BACKGROUND: Concomitant venous thromboembolism (VTE) and left atrial appendage (LAA) thrombus associated with cancer is exceedingly rare. The use of direct factor Xa inhibitors in patients with cancer is controversial. CASE SUMMARY: We report a rare case of concomitant VTE and LAA thrombus in an 85-year-old man with prostate cancer. He developed VTE and LAA thrombus, while on warfarin therapy for non-valvular atrial fibrillation. Despite optimal medical treatment with warfarin, systemic thrombosis developed. After thrombolysis, he was prescribed apixaban, an oral direct factor Xa inhibitor, as maintenance therapy. Deep venous thrombosis, pulmonary embolism, and LAA thrombus were effectively treated, and his symptoms resolved. DISCUSSION: Despite the fact that many patients with cancer are in a hypercoagulable state, to the best of our knowledge, this is a first case describing VTE and LAA thrombus presenting concomitantly during optimal warfarin therapy. This case demonstrates the importance of awareness of systemic thrombosis in patients with cancer regardless of vitamin K antagonist therapy. More cases and larger scale data are needed to investigate if factor Xa inhibitors are useful for treating systemic thrombosis in patients with cancer.