Dabigatran for stroke prevention in nonvalvular atrial fibrillation: answers to challenging "real-world" questions

Dabigatran reversal with idarucizumab in a patient undergoing heart transplantation: first European report

Background

Dabigatran is a direct thrombin inhibitor with a favorable effectiveness and safety profile when compared to vitamin K antagonists, both in randomized trials and real world registries of atrial fibrillation patients. Yet, physicians’ fear of high bleeding risk scenarios in daily clinical practice still precludes a more widespread use of oral anticoagulation. We hereby report a successful case of dabigatran reversal with the novel monoclonal antibody fragment idarucizumab in a patient undergoing heart transplantation.

Case presentation

A 45-year old male patient on dabigatran for atrial fibrillation thromboprophylaxis was enlisted for heart transplantation due to end-stage ischemic heart failure. Upon donor availability and suitability and following the last intake of the drug 12 h previously, activated partial thromboplastin time was measured and found to be elevated. After general anesthesia and before extracorporeal circulation, idarucizumab was administered as two boluses of 2.5 g. Orthotopic heart transplantation ensued under full heparinization and cardiopulmonary bypass. Total chest tube output was 1125 mL after 3 days and 4 units of fresh frozen plasma and one platelet pool were administered in the operating room without further need for blood products. The post-operative period was uneventful.

Conclusions

Idarucizumab was associated with an effective hemostasis in the setting of heart transplantation. Dabigatran may be considered as an alternative to vitamin K antagonists in heart transplant candidates with an indication for oral anticoagulation.

Monitoring of dabigatran therapy using Hemoclot(®) Thrombin Inhibitor assay in patients with atrial fibrillation

Dabigatran, a new direct thrombin inhibitor, achieves strong anticoagulation that is more predictable than warfarin. Nevertheless, a patient on dabigatran therapy (DT) may suffer from thrombotic or bleeding events. The routine monitoring of DT is not recommended, and standard coagulation tests are not sensitive enough for the assessment of DT activity. The aim of this study was to examine the clinical usefulness of the Hemoclot(®) Thrombin Inhibitor (HTI) assay in the assessment of dabigatran plasma levels in patients with non-valvular AF. Nineteen patients (12 men, 7 women) on DT were included in this preliminary prospective observational study. Dabigatran was administrated twice daily in a two dose regimens: 150 mg (5 patients) and 110 mg (14 patients). Blood samples were taken for the assessment of trough and peak levels of dabigatran. Dabigatran concentrations were measured with the HTI assay. The average dabigatran trough level was 69.3 ± 55.5 ng/ml and the average dabigatran peak level was 112.7 ± 66.6 ng/ml. The dabigatran trough plasma concentration was in the established reference range in 15 patients and the dabigatran peak plasma concentration was in the established reference range in 9 patients, respectively. Despite the fact that the activated partial thromboplastin and thrombin times were generally changed (prolonged), these tests failed to identify the patients with too low or too high dabigatran concentrations. The study confirmed the high sensitivity of the HTI assay for the assessment of dabigatran plasma levels. When compared to standard coagulation tests, the HTI is a more suitable assay for the monitoring of patients treated with dabigatran. Monitoring of DT may be beneficial in selected patients; however, further studies will be needed for the final clarification of this issue.