Relation of preoperative use of aspirin to increased mediastinal blood loss after coronary artery bypass graft surgery.

To evaluate the potential effect of aspirin, a platelet inhibitory agent, on postoperative bleeding complications after coronary artery bypass graft surgery, we compared each of nine patients who had taken aspirin within 7 days prior to operation to one or two control subjects (total 16 patients) matched for age, sex, extent of coronary disease, number of grafts placed total operative time, bypass time, and preoperative use of propranolol. Preoperative prothrombin time, partial thromboplastin time, and platelet counts were normal for all patients. Mean mediastinal blood loss was significantly greater in the aspirin group (919 +/- 164 ml., S.E.) than in the control group (437 +/- 61 ml., p less than 0.001). The degree of mediastinal blood loss did not correlate with patient age, total operative time, bypass time, number of vessels diseased, or grafts placed. In addition, compared to controls the aspirin group required prolonged chest tube drainage (33 +/- 5 hours versus 19 +/- 1 hour, p less than 0.001).