Probably due to genetic variations, there is quite some variability in the responsiveness to the platelet aggregation inhibitor clopidogrel between individual patients. Most research so far has focused on the reduced efficacy of this type of antiplatelet therapy in low responders. However, in this article the authors have studied the other side of the coin, i.e. the risk of increased blood loss in clopidogrel users that have a relatively high antiplatelet effect of the drug. Indeed, the authors show, in 100 patients undergoing off-pump coronary artery bypass grafting, that they could relate the platelet inhibitory response (measured by a thrombelastographic method) to the amount of blood lost and to transfusion requirements. This effect was independent of the time of interruption of clopidogrel treatment before the operation (1 or 3 days). This is an interesting study that demonstrates that increased perioperative bleeding risk due to clopidogrel may be predicted based on ex vivo platelet reactivity. Thereby, patients at a higher risk of bleeding may be identified and may be candidates for additional measures to prevent major perioperative blood loss.

– Marcel Levi