Aspirin- and coumadin-related bleeding after coronary- artery bypass graft surgery.

We studied 100 consecutive patients to evaluate the potential effect of platelet active and antithrombotic agents prescribed preoperatively on bleeding complications after coronary-artery bypass graft surgery. Preoperative hemostatic values were normal in all patients. Mean mediastinal blood loss was significantly greater in 13 patients taking aspirin (892 +/- 91 ml) and six patients taking Coumadin (warfarin sodium) (858 +/- 168 ml) within 7 days of surgery than in 64 control subjects (439 +/- 28, P less than 0.001). Less marked but similar differences (P less than 0.05) were noted with other agents inhibiting platelet function. However, in nine patients given heparin, mean mediastinal blood loss (436 +/- 61 ml) was no different from that of control subjects. The degree of mediastinal blood loss did not correlate with age, sex, mean total operative time, bypass time, or number of vessels diseased or bypassed. In addition, patients taking aspirin or Coumadin required prolonged chest tube drainage compared to those in heparin or control groups (34 +/- 4 versus 20 +/- 1 h) (P less than 0.001).