Inhibition of platelet aggregation by combined therapy with aspirin and cilostazol after off-pump coronary artery bypass surgery.

BACKGROUND Although off-pump coronary artery bypass (OPCAB) has become an increasingly common surgical procedure, recent concerns have been raised regarding the existence of a hypercoagulable or prothrombotic state associated with OPCAB. To determine the optimal antiplatelet regimen after OPCAB, we investigated the effects of aspirin alone and of combined therapy with aspirin + cilostazol on platelet aggregation in patients after OPCAB. MATERIAL AND METHODS Twenty patients scheduled to undergo OPCAB were randomized to one of two antiplatelet regimens: aspirin alone (n=10) and aspirin + cilostazol (n=10). Anti-platelet agents had not been received for at least 1 week before surgery and were initiated on the afternoon of postoperative day 1. Platelet aggregability and hemostatic parameters were evaluated at four time points: before and 3, 7, and 14 days after OPCAB. We measured agonist-and shear stress-induced platelet aggregation (SIPA) using a modified cone-plate viscometer. RESULTS No complications resulting from postoperative antiplatelet therapy-related bleeding were seen in either group. Collagen-and arachidonate-induced platelet aggregation and SIPA were significantly inhibited in the aspirin + cilostazol group compared with the aspirin-alone group (collagen-and arachidonate-induced aggregation, p<0.0001; SIPA, p=0.0367). Adding cilostazol to aspirin augmented the inhibitory effects on platelet aggregation induced by collagen and arachidonate. adenosine diphosphate (ADP)-induced platelet aggregation tended to be inhibited in the aspirin + cilostazol group compared with the aspirin-alone group (p=0.0534). CONCLUSION The results of this study suggest that combined therapy with aspirin + cilostazol is more effective than aspirin monotherapy in reducing platelet aggregation in patients after OPCAB. This combination therapy may represent a new therapeutic option for an anti-thrombotic regimen in patients after OPCAB.