Monitoring the Antiplatelet Effect of Cilostazol with Light Transmission Aggregometer: Two Cases of Possible Cilostazol Resistance

eISSN 2093-6338 let-derived growth factors and thicken the intima of vessel walls, worsening symptoms [1]. It is important to prescribe antiplatelet agents to prevent thrombus formation in patients with a stent insertion. Aspirin and clopidogrel are the major antiplatelet agents used. Aspirin is a cyclooxygenase (COX) inhibitor and prevents platelet aggregation by inhibiting the formation of thromboxane A2. Clopidogrel is a 5 -adenosine diphosphate (ADP) receptor blocker and inhibits platelet aggregation by increasing the amount of cyclic adenosine monophosphate (cAMP) in platelets. Recently, patients showing high post treatment platelet reactivity (HPPR) after taking antiplatelet agents have been reported to show worse prognoses. The frequency of HPPR is reported to be 5-45% in patients taking aspirin [2] and 4-30% in patients taking clopidogrel [3]. Methods for monitoring the effects of these medications have been deINTRODUCTION