BACKGROUND: Specific reversal agents for non-vitamin K antagonist oral 
anticoagulants are lacking. Idarucizumab, an antibody fragment, was developed to 
reverse the anticoagulant effects of dabigatran.
METHODS: We undertook this prospective cohort study to determine the safety of 5 
g of intravenous idarucizumab and its capacity to reverse the anticoagulant 
effects of dabigatran in patients who had serious bleeding (group A) or required 
an urgent procedure (group B). The primary end point was the maximum percentage 
reversal of the anticoagulant effect of dabigatran within 4 hours after the 
administration of idarucizumab, on the basis of the determination at a central 
laboratory of the dilute thrombin time or ecarin clotting time. A key secondary 
end point was the restoration of hemostasis.
RESULTS: This interim analysis included 90 patients who received idarucizumab 
(51 patients in group A and 39 in group B). Among 68 patients with an elevated 
dilute thrombin time and 81 with an elevated ecarin clotting time at baseline, 
the median maximum percentage reversal was 100% (95% confidence interval, 100 to 
100). Idarucizumab normalized the test results in 88 to 98% of the patients, an 
effect that was evident within minutes. Concentrations of unbound dabigatran 
remained below 20 ng per milliliter at 24 hours in 79% of the patients. Among 35 
patients in group A who could be assessed, hemostasis, as determined by local 
investigators, was restored at a median of 11.4 hours. Among 36 patients in 
group B who underwent a procedure, normal intraoperative hemostasis was reported 
in 33, and mildly or moderately abnormal hemostasis was reported in 2 patients 
and 1 patient, respectively. One thrombotic event occurred within 72 hours after 
idarucizumab administration in a patient in whom anticoagulants had not been 
reinitiated.
CONCLUSIONS: Idarucizumab completely reversed the anticoagulant effect of 
dabigatran within minutes. (Funded by Boehringer Ingelheim; RE-VERSE AD 
ClinicalTrials.gov number, NCT02104947.).