| OBJECTIVES:1. To observe the variation of platelet count and function after off-pump and on-pump coronary artery bypass.2. To compare the impact of three strategies for the management of antiplatelet therapy (aspirin, clopidogrel, aspirin plus clopidogrel) on patients during the early period after coronary artery bypass grafting without CPB(OPCAB), the impact on grafts and their distal anastomoses'patency in 6 months-1 year follow-up by means of 64-MSCTA.3. To compare the three strategies for the management of antiplatelet therapy on inhibition for neointimal hyperplasia in rabbit's autologous vein graft.MATERIALS and METHODS:1. From June 2009 to March 2010, sixty patients having received off-pump and on-pump coronary artery bypass grafting (OPCAB and CCABG) were retrospectively analyzed. Aspirin was managed (100mg 1/d) after operation. Platelet function was assessed by using adenyl diphosphoric acid-induced platelet aggregation (PAG). Blood samples were collected before the operation, immediately postoperatively, and on days 1,5, and 10. Platelet count was recorded collected before the operation, immediately postoperatively, and on days 1,3, and 10. The values on day of the operation were corrected according to hematocrit.2. From August 2008 to June 2009,180 patients undergoing coronary artery bypass grafting without CPB were randomly assigned to three groups. Impact of three antiplatelet therapy on blood coagulation function, drainage volume, number of platelet and neutrophilic granulocyte, function of platelet were compared among three groups. The patency of LIMA grafts and SVGs and their distal anastomoses as well were analyzed by means of 64-MSCTA in 6 months～1 year follow-up after operation.3. Thirty-two New Zealand rabbits were randomly assigned to four groups and the animal model was established by implanting right external jugular vein into the externaIcarotid of the same side with "cuff" technique. Three of the four groups were respectively given aspirin, clopidogrel, aspirin plus clopidogrel after operation. The vein grafts were removed after 6 months for observation under transmission electron microscope and scanning electron microscope. The thickness, area of newly born intima and media were measured. The expression of Bax and Bcl-2 was observed.RESULTS:1. In both groups, platelet count decreased transiently after operation and soon increased markedly (P<0.01). The change in CCABG group was more obvious. PAG also increased markedly in both groups (P<0.05). On day 10, PAG recovered in OPCAB group but was still higher in CCABG group (P<0.05).2. Prothrombin time, activated partial thromboplastin time were tested and there were no significant differences among the three groups. Proserozym activity was higher in group of aspirin plus clopidogrel than group of aspirin (P<0.05) Drainage volume, number of platelet and neutrophilic granulocyte showed no significant differences among them. PAG was lower in aspirin plus clopidogrel group than another two groups (P<0.05). In postoperative 6 months～1 year's follow-up, with arithmetic method of Fitzgibbon A+B, there were no significant differences in patency of LIMA grafts and SVGs as well as distal anastomoses on LIMA grafts in the three groups (p>0.05). But the patency of distal anastomoses on SVGs in asprin plus clopidogrel group was higher than that in asprin group. With arithmetic method of Fitzgibbon A, there were no significant differences in patency of LIMA grafts among three groups. The patency of SVGs was higher in asprin plus clopidogrel group than in asprin group. There were no significant differences in LIMA distal anastomoses among three groups. The patency of SVGs distal anastomoses was higher in asprin plus clopidogrel group than in asprin group and in clopidogrel group respectively (p<0.05).3. Transmission electron microscope showed the thickness of intima, elastic fiber and collagen fibers increased obviously. There were no significant differences in thickness, area of newly born intima, expression of Bax and Bcl-2 between clopidogrel group and aspirin plus clopidogrel group, but both were lower than that of controling group and aspirin group. There were no significant differences between controling group and aspirin group.CONCLUSION:1. Platelet count and function both increase after CABG regardless of CPB, but more markedly in those using CPB. This probably is one of the principal causes for aspirin resistance after CABG.2. The three strategies of antiplatelet therapy are all safe during the early period of management after OPCAB. The management of aspirin plus clopidogrel can superiorly inhibite thrombocytic function than aspirin or clopidogrel alone. In postoperative 6 months～1 year's follow-up, there were no significant differences in patency of LIMA grafts and their distal anastomoses in three groups (p>0.05). The patency of SVGs and their distal anastomoses was higher in asprin plus clopidogrel group than in asprin group and clopidogrel group respectively (p<0.05). The safety of three strategies of antiplatelet therapy was proven within 1 year post operation. Asprin plus clopidogrel was advised to be managed for patients who have severe coronary artery disease.3. Clopidogrel can efectively lessen the vein graft intima thickness and area, which was not enhanced by adding aspirin.
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