Influence of aspirin or heparin on platelet function and postoperative blood loss after coronary artery bypass surgery.

The aim of the study was to assess the effect of aspirin or heparin pretreatment on platelet function and bleeding in the early postoperative period after coronary artery bypass grafting (CABG) surgery. Seventy-five male patients with coronary artery disease who underwent CABG with cardiopulmonary bypass (CPB) were studied. The patients were divided into three groups: Group 1 (n=25) included patients receiving aspirin pretreatment, Group 2 (n=22) received heparin pretreatment, and Group 3 (n=28) included patients who received no antiplatelet or anticoagulant pretreatment. Twenty-four hours after surgery, all patients were administered aspirin therapy that was continued throughout their hospitalization period. We assessed the following preoperative blood coagulation indices: activated partial thromboplastin time (aPTT), international normalized ratio (INR), and fibrinogen. We compared platelet count and platelet aggregation induced by adenosinediphosphate (ADP) before surgery, 1 h after surgery, 20 h after surgery and on the seventh postoperative day. We assessed drained blood loss within 20 postoperative hours. Preoperative blood coagulation indices did not differ among the groups. Platelet count was also similar. One hour after surgery, platelet count significantly decreased in all groups (p<0.001), after 20 postoperative hours it did not undergo any marked changes, and on the seventh postoperative day, it significantly increased in all groups (p<0.001). Before surgery, the lowest index of ADP-induced platelet aggregation was found in Group 1 (p<0.05). One hour after surgery, platelet aggregation significantly decreased in all groups, most markedly in Group 3 (p<0.001), yet after 20 h, its restitution tendency and a significant increase in all groups was noted. On the seventh day, a further increase in the statistical mean platelet aggregation value was noted in Groups 2 and 3. Comparison of platelet aggregation after 20 postoperative hours and on the seventh day after surgery revealed a significantly higher than 10% increase of the index in 32% of patients in Group 1 (p<0.05), 27.3% of patients in Group 2 (p<0.05) and in 35.7% of patients in Group 3 (p<0.001). The lowest statistically significant value of postoperative blood loss was noted in Group 2 (p<0.01). Our study has shown that aspirin or heparin pretreatment had no impact on the dynamics of platelet function in the early postoperative period after CABG. The lowest postoperative blood loss was noted in patients pretreated with heparin.