Usefulness of monitoring platelet function by multiple electrode aggregometry in primary coronary artery bypass surgery.

Objectives: Antiplatelet therapy commonly is used for the prevention of cardiovascular complications but increases the risk of perioperative bleeding. Multiple-electrode aggregometry (MEA) was investigated for monitoring platelet inhibition by acetylsalicylic acid (ASA) and clopidogrel in patients undergoing elective coronary artery bypass graft (CABG) surgery with regard to clinical outcome as measured by postoperative blood loss and transfusion requirements.

Design: A prospective observational study.

Setting: A teaching hospital.

Participants: One hundred fifty patients scheduled for elective CABG surgery were included: without antiplatelet therapy (group A, n = 50), single ASA exposure (group B, n = 50), and combined therapy with ASA and clopidogrel (group C, n = 50).

Measurements And Main Results: MEA was assessed preoperatively using either collagen (COL-MEA) or ADP (ADP-MEA). Postoperative blood loss and transfusion requirements were recorded for 24 hours after surgery. Postoperative blood loss significantly increased only from combined antiplatelet therapy (group A: 572 ± 297 mL, group B: 721 ± 356 mL, group C: 865 ± 346, p < 0.01) and correlated with ADP (r(p) = -0.35, p < 0.01) and COL-MEA (r(p) = -0.23, p > 0.01). COL-MEA and ADP-MEA discriminated between preoperative ASA and clopidogrel intake (ASA: sensitivity = 86.3%, and specificity = 89.3%; clopidogrel: sensitivity = 87.5%, and specificity = 95.1%). The postoperative transfusion risk was increased in patients diagnosed for clopidogrel treatment by ADP-MEA (odds ratio = 2.92; confidence interval: 1.44-5.92; p = 0.005).

Conclusions: MEA is a suitable method for the detection of platelet inhibition by ASA and clopidogrel in patients undergoing CABG surgery. In these patients, preoperative ADP MEA seems to indicate patients at risk for postoperative transfusion requirements.