Bleeding after cardiac surgery correlates with morbidity and mortality. The aim of this study was to determine the influence of antiplatelet therapy on bleeding and transfusion rates in coronary artery bypass grafting.

Forty patients receiving aspirin and/or clopidogrel/ticlopidine within 7 days prior to surgery were retrospectively compared to 40 control patients lacking antiplatelet therapy for at least 8 preoperative days. Blood loss was assessed as chest-tube drainage during the first 12 h after surgery. Units transfused were recorded intraoperatively and during stay in the intensive care unit.

Both groups were comparable for pre- and intraoperative data. Irrespective of single or combined antiplatelet therapy, treated patients demonstrated lower fractions of the creatine-kinase isoenzyme MB (5.8 ± 3.1 vs. 8.2 ± 4.1%; P = 0.004) and infarction rates (0 vs. 3; P = 0.240) than control patients, but had significantly more haemorrhages (940 ± 861 mL vs. 412 ± 590 mL; P = 0.002) and transfusion requirements (red cells: 4.5 ± 4.9 vs. 1.5 ± 2.3, plasma: 4.9 ± 6.4 vs. 1.3 ± 2.5, platelets: 1.5 ± 1.3 vs. 0.1 ± 0.2; all P ⩽ 0.001). The differences to control patients were more pronounced for only short antiplatelet therapy free intervals or ongoing antiplatelet therapy (P⩽2 days ⩽ 0.019). For antiplatelet therapy free intervals longer than 2 days, bleeding and transfusion rates (except for platelets) were nonsignificantly higher as compared to control patients (P ⩾ 0.058).

To overcome increased blood loss and transfusion rates, antiplatelet therapy should be discontinued for at least 2 days before elective coronary surgery. Whether patients at high risk for myocardial infarction might benefit from ongoing antiplatelet therapy remains to be investigated.