[Successful direct thrombin inhibitor treatment of a left atrial appendage thrombus developed under rivaroxaban therapy].

The authors present the history of a 62-year-old man on continuous rivaroxaban therapy who was scheduled for pulmonary vein isolation due to persistent atrial fibrillation. Preoperative transesophageal echocardiography detected the presence of left atrial appendage thrombus. Thrombophilia tests showed that the patient was heterozygous carrier of the methylene-tetrahydrofolate reductase gene mutation. The authors hypothesized that a direct thrombin inhibitor might exert a more appropriate effect against thrombosis in this case and, therefore, a switch to dabigatran was performed. After two months of anticoagulation with the direct thrombin inhibitor and folic acid supplementation the thrombus resolved. The authors underline that thrombus formation may develop in atrial fibrillation even if the patient is adequately treated with rivaroxaban. This case suggests, that methylene-tetrahydrofolate reductase gene mutation may modulate the efficacy of direct Xa factor inhibitors. According to this case history, dabigatran may be an effective therapeutic option in resolving established thrombus.