Platelets are anuclear cell fragments derived from mega- karyocytes that function in the clotting system and circulate in blood for a life span of 6–9 days. Platelets play a major

Platelets are anuclear cell fragments derived from megakaryocytes that function in the clotting system and circulate in blood for a life span of 6–9 days. Platelets play a major role in the thromboembolic diseases, upon vascular injury, especially arterial vascular injury; platelets rapidly adhere to the exposed subendothelial area, where they become activated by contacting with stimulants like collagen, resulting in the recruitment of additional platelets from circulation to form a stable arterial plug. Platelet plug formation is the primary phase of homeostasis physiologically and pathologically. It has been widely accepted and confirmed that antiplatelet therapy remains extremely important in treatment and prophylaxis of arterial thromboembolic disorders such as coronary arterial diseases (CAD) and stroke. Antiplatelet drugs (APDs) are a large group of powerful pharmacological agents that interfere with the physiologic activities of platelets and prevent the formation of blood clots. APDs are widely prescribed for the patients with history of CAD, heart attack, angina, atrial fibrillation, and so forth. APDs are also used after procedures of angioplasty, stent placement, and coronary artery bypass grafting (CABG) to prevent stenosis and clotting. This review discusses the category, mechanisms, and clinical trials of common APDs that are used in the treatment of CAD. We also discuss perioperative use of APDs in the CABG procedures, association of platelet inhibition with cardiopulmonary bypass-induced inflammation, and APDs resistance. Abstract: Platelets play a major role in the thromboembolic diseases and upon vascular injury, especially arterial vascular injury. These platelets rapidly adhere to the exposed subendothelial area, where they become activated by contacting with stimulants. Antiplatelet therapy remains extremely important in treatment and prophylaxis of arterial thromboembolic disorders such as coronary arterial diseases and stroke. The antiplatelet drugs (APDs) are among the most widely used in the world. Based on the molecular targets, APDs are classified as Thromboxane A2 pathway blockers, ADP receptor antagonists, GPIIa/IIIb antagonists, adenosine reuptake inhibitors, phosphodiesterase inhibitors, thrombin receptor inhibitors, and others. Coronary artery bypass graft (CABG) surgery is an important therapeutic approach to treat coronary artery disease. Long-term success after CABG depends on the patency of the bypass vessels. Since platelets play a crucial role in the pathogenesis of thrombosis in the blood vessels, APDs are broadly used to reduce serious cardiovascular events. Platelets also are an integral part of inflammation and APDs have demonstrated to reduce the inflammation mediators in the healthy volunteers and coronary artery disease patients; it will be an interesting topic to determine if platelet inhibition will attenuate CPB-induced systemic inflammatory response syndrome. Due to concerns of post-op bleeding with use of APDs, it is a common practice to withhold APDs prior to surgery; however, recent studies have demonstrated that continuation of APDs prior to surgery (even until the day of surgery) does not increase the risk of post-op bleeding. With extensive use of APDs in cardiovascular thromboembolic events, APD resistance becomes problematic in clinical antiplatelet therapy. Since there is no standardized or universal definition available to quantify APDs resistance, a clinically meaningful definition of APD resistance needs to be developed based on data linking laboratory tests to clinical outcomes in patients.