The prodrug of dabigatran - dabigatran etexilate, rapidly converted into its active form via per os, is a kind of non-vitamin K antagonist oral anticoagulant, acting as a direct reversible and competitive inhibitor for both free and platelet-bound thrombin, thereby affecting the final step of blood clotting.[5] Since its short half-life, rapid onset of action, less effect on food and drugs, and no need to monitor the INR, etc.[6], it is deemed to be a type of safer and more effective medicine to prevent stroke. Nevertheless, Dabigatran’s elimination is highly dependent on the kidney function; about eighty-five percent of plasma dabigatran is excreted through the kidneys, and the process can be prolonged with RI.[7] The RE-LY study demonstrated that dabigatran could reduce all-cause mortality and intracranial hemorrhage, but increased gastrointestinal (GI) bleeding compared with warfarin. The risk of dabigatran-related GI bleeding seems to be evenly distributed between the upper and the lower canals (53 vs. 47%); whereas warfarin-related the upper dominated (75 vs. 25%). The mechanism of its bleeding remains unclear; one possible theory, as noted that local metabolism of dabigatran etexilate leads to an increase in active dabigatran concentrations during transit through the GI tract.[8, 9] Dabigatran-induced GI hemorrhage is also related to the age, which chiefly occurs among patients aged 75 years and older.[10] Helicobacter pylori (Hp) infection, liver cirrhosis, malignant tumors, genetic factors, and history of major bleeding, of peptic ulcer or of GI injury, such as diverticulosis and intestinal vascular dysplasia can also increase the risk of bleeding.[11, 12] As the study shows PPI–dabigatran coadministration can not only significantly reduce the risk of upper GI hemorrhage, but also the dabigatran plasma levels in patients with AF.[13]
The patient, in this case report, a 76-year-old Asian woman, has a history of AF and concealed progressive RI, with a long-term does-adjustment DT for one year, short of regular blood coagulation function monitoring and orally administered PPI. The massive hemorrhage from the gastric mucosal was likely affected by prolonged dabigatran excretion resulting from RI.
Idarucizumab is a sort of humanized monoclonal antibody that specifically and efficiently inhibits the biological activity of dabigatran etexilate. After antibody–antigen binding, it neutralizes the anticoagulant effect irreversibly. The binding affinity of idarucizumab-dabigatran is 350 times higher than that of dabigatran-thrombin, and the reversal consequence shows a rapid onset and lasts for 12 hours, of which are suitable for life-threatening bleeding, uncontrolled hemorrhage, or emergency surgery of the patients with dabigatran.[14, 15] It has been reported that a single dose of 5g idarucizumab for 98% of patients is sufficient to reverse the effect of dabigatran etexilate, and most patients can maintain 24 hours.[16] Considering the extensive gastric mucosal bleeding, endoscopic hemostasis was less efficacious for her. The conventional therapy of acid suppressive, hemostatic and blood transfusion did not achieve hemostasis, and then idarucizumab was given to reverse the effect of dabigatran for rescuing the 2ed time life-threatening bleeding. Since then, the patient, whose coagulation function became normal during hospitalization, was deprived of the symptoms of hematemesis and melena, with Hb growing to 104g/L on the 14th day. Finally, she was discharged in a stable condition.