Left atrial appendage thrombus formation in a patient with atrial fibrillation on dabigatran therapy associated with CES1 and ABCB1 genetic polymorphisms: A case report

RATIONALE: Dabigatran is a direct thrombin inhibitor that is widely used to prevent the formation of thrombus formation. Amiodarone can increase the plasma concentration of dabigatran. CES1 (carboxylesterase 1) and ABCB1 (ATP-binding cassette subfamily B member 1) genetic polymorphisms associate with the pharmacokinetics of dabigatran. PATIENT CONCERNS: A 62-year-old woman was admitted to the hospital due to chest tightness, fatigue, and discomfort despite long-term anticoagulation with dabigatran 110 mg twice daily for 6 months, with concomitant use of amiodarone. DIAGNOSES: Left atrial appendage thrombus formation with a history of atrial fibrillation. INTERVENTIONS: The clinician changed dabigatran to warfarin. To explore the causes of insufficient anticoagulation using dabigatran in this patient, we examined the ABCB1 and CES1 genes. Results showed that she carried ABCB1 variant alleles with 3 heterozygote single nucleotide polymorphisms (SNPs: rs4148738, rs1045642, rs2032582) and CES1 variant alleles with 2 heterozygote SNPs (rs2244613, rs4580160). OUTCOMES: The left atrial appendage thrombus disappeared. LESSONS: Multiple mutations in the ABCB1 and CES1 genes may influence the pharmacokinetics of dabigatran and could have contributed to the thrombus formation in the left atrial appendage.