Objective: Despite of non-vitamin K antagonist oral anticoagulants (NOACs) is a preferred oral anticoagulant but in limited-resource country, warfarin still be first line drug. Bridging parenteral anticoagulant with warfarin is required in particular circumstances. Since a NOACs contains rapid onset and steady activity characteristics, then the use of NOACs instead of traditional parenteral anticoagulant to bridging with warfarin is intriguing.
Materials and Methods: We conducted an open-label, randomized, pilot study in patients with atrial fibrillation (AF) and thromboembolism who considerably required bridging therapy to apixaban (5 mg orally bid) or enoxaparin (1 mg/kg subcutaneously every 12 hours) bridging to warfarin. The dose of warfarin was adjusted every 3 to 5 days to achieve the goal of international normalized ratio (INR) between 2 to 3 before stopping the bridging. The primary outcome was bleeding complication classified as the Bleeding Academic Research Consortium (BARC) criteria. The secondary outcome included thromboembolic complication, mean change of hemoglobin (Hb) level during bridging, and cost of anticoagulant.
Results: A total of 37 patients underwent randomization after stratified to AF and thromboembolism groups from 60 patients screened, which 19 assigned to apixaban and 18 to enoxaparin. Six patients were excluded after randomization (1 in apixaban group and 5 in enoxaparin group), the data before the patients were excluded were used in the analysis. The median (interquartile range) bridging duration was 7 (5 to 10) and 9 (6 to 14.5) days for apixaban and enoxaparin, respectively. There was null BARC bleeding in apixaban group whereas 3 patients developed BARC 1 bleeding in enoxaparin group (p=0.058). Thromboembolic complication was not occurred in any group during the bridging. The median cost of anticoagulant was 674 and 4,352 Thai Baht (p<0.001) and mean change of Hb level was +0.36 and -0.38 g/dl in apixaban and enoxaparin group (p=0.029), respectively.
Conclusion: Apixaban was as safe, effective, and less expensive than enoxaparin in bridging to warfarin in patients with AF and thromboembolism.

Keywords: Bridging anticoagulant; NOACs; Apixaban; Enoxaparin; Warfarin