Clopidogrel and bleeding in patients undergoing elective coronary artery bypass grafting.

Objective: In an effort to minimize transfusions in patients undergoing elective coronary artery bypass grafting operations after recent clopidogrel exposure, we studied laboratory tests predictive of platelet dysfunction and used a strict algorithm-driven treatment of bleeding.

Methods: Forty-five patients receiving clopidogrel within 6 days of the operation and 45 control subjects were studied. Prothrombin time, activated partial thromboplastin time, platelet count, and platelet function test results were measured before heparinization, after protamine administration, and then every 2 hours. No transfusions were administered unless a patient met both laboratory and clinical criteria.

Results: Algorithm-driven treatment of bleeding significantly reduced the mean units of all blood components transfused by about one third, as shown by comparison with current control and historical data. Compared with current control subjects, clopidogrel recipients required significantly more transfusions of platelets (9.0 +/- 1.7 vs 1.2 +/- 0.5 U; P <.0001) and packed red blood cells (4.3 +/- 0.6 vs 2.3 +/- 0.5 U; P =.01) and required longer periods of controlled ventilation (12.4 +/- 1.3 vs 8.6 +/- 0.8 hours; P =.02). Preoperative platelet dysfunction before heparin administration for cardiopulmonary bypass, as measured by using adenosine diphosphate aggregometry (response <40%), predicted all but 1 case of severe coagulopathy requiring multiple transfusions (16.6 +/- 2.8 U of platelets and 5.8 +/- 1.0 U of packed red blood cells).

Conclusions: A strict transfusion algorithm can reduce the transfusion requirement for all blood components. Preheparin testing of platelet function with adenosine diphosphate aggregometry can identify patients at highest risk for perioperative bleeding and transfusions and might further reduce the perioperative transfusion requirement.