[Rivaroxaban-resistant right ventricular thrombus, successfully treated with vitamin K antagonist in a patient with dilated cardiomyopathy].

Rivaroxaban, a selective inhibitor of active factor X belongs to the group of direct-acting oral anticoagulants (DOAC), more and more often replacing vitamin K antagonists (VKA) in venous thromboembolic disease and nonvalvular atrial fibrillation. Attempts are also being made to use DOAC to treat locally formed intracardiac thrombi, mainly in the left atrium and its appendage, in atrial fibrillation and in heart failure. Rarely diagnosed local right ventricular thrombus (RVT) may be a complication of dilated cardiomyopathy (DCM). CASE REPORT: The authors present a case of a 40-year-old male with DCM and RVT located in the apex, which was imaged in echocardiography, magnetic resonance and multislice computed tomography. During treatment with rivaroksaban (2x15 mg: 4 weeks; 1x20 mg: 4 months) diminishing of RVT was not observed. After 2 months of VKA use complete resolution of RVT was noted. The case presented is probably the first described RVT treated with rivaroxaban. The authors conclude that in some cases, anticoagulation with VKA may be more effective than DOAC in intracardiac thrombi therapy, especially when it is meticulously monitored. Overlapping effect on RVT due to anticoagulants use with a different mechanism of action cannot be excluded.