Patients on antiplatelet agents and who are undergoing cardiac surgery have a risk of higher perioperative blood losses and increased transfusion requirements. The present study tested the hypothesis that tranexamic acid is useful in reducing perioperative blood losses in patients that had been on or were still using clopidogrel at the time of cardiac surgery in a multicenter, randomized blinded study. Tranexamic acid was given at a dose of 10 mg/kg as a bolus followed by 10 mg/kg/hr. The use of clopidogrel was associated with 270 mL more blood loss and an 18.5% increased risk of major bleeding. Tranexamic acid reduced perioperative blood loss by 278 mL, the risk of bleeding by 19.5%, and resulted in a 19% decrease in red blood cell exposure.

The subgroup of patients that presented a demonstrated decreased platelet function (as assessed by thrombelastography) benefited most from tranexamic acid administration. There were no differences in clinically relevant outcomes, such as reoperation, organ dysfunction, myocardial infarction, or death.

This is an interesting trial demonstrating that tranexamic acid is effective and probably safe in patients undergoing cardiac surgery and who are on clopidogrel. The most prominent risk of bleeding and associated detrimental adverse events, however, are found in patients using the combination of aspirin and clopidogrel. Hence, a study demonstrating the protective effect of tranexamic acid in patients using dual antiplatelet agents would have been even more relevant. Remarkably, the use of aspirin in the present study was not mentioned at all.

In conclusion, tranexamic acid is a useful agent to prevent excessive perioperative blood loss and transfusion requirements in selected patients undergoing cardiac surgery at high risk of bleeding. As demonstrated in this study, the pre- and perioperative use of clopidogrel may be such a selection criterion.

– Marcel Levi