Tranexamic acid is an antifibrinolytic agent that is commonly used to control bleeding in patients undergoing cardiac surgery. Limited randomized controlled trial data, however, are available to determine the optimal dose. High doses of tranexamic acid have been associated with seizures and thrombotic events. In order to determine the optimal dose, the multicenter, double-blind Outcome Impact of Different Tranexamic Acid Regimes in Cardiac Surgery with Cardiopulmonary Bypass (OPTIMAL) trial compared high- (30 gm/kg initial bolus, 16 mg/kg/h maintenance dose during surgery, and 2 mg/kg pump prime dose) and low-doses of tranexamic acid (10 mg/kg initial bolus, 2 mg/kg/h maintenance dose, and 1 mg/kg prime dose). The study enrolled 3079 patients (mean age, 52.8 years; 38.1% female) from 2018 to 2021; 333 of 1525 patents (21.8%) in the high dosage group received red blood cell (RBC) transfusions compared to 391 of 1506 patients (26.0%) in the low dose group (p=0.004). The safety profile of high doses of tranexamic acid was noninferior to low doses. A composite safety endpoint (30-day mortality, seizure, kidney dysfunction, and thrombotic events) was similar in both groups—17.6% in the high-dose group compared to 16.8% in the low dose group. A higher dose of tranexamic acid modestly reduced the need for RBC transfusions in patients undergoing cardiac surgery and met the criteria for noninferiority for safety. Further trials comparing tranexamic acid dosage in other populations are needed to confirm these findings.
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