Platelets, atherothrombosis, and atherosclerosis

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. In 2008 alone, 17.3 million deaths (representing 30% of all deaths) were attributable to the complications of cardiovascular disease. Of these deaths, 7.3 million were due to coronary artery disease while 6.2 million were attributable to stroke. Cardiovascular disease is expected to remain the leading cause of death globally, with the number of deaths expected to reach 23.6 million annually by 2030 (WHO statistics, 2012). Vascular disease arises through the complications of atherosclerosis, a complex chronic inflammatory condition affecting the arterial circulation. It leads to the development of vascular lesions or atherosclerotic plaques, which manifest as asymmetrical thickenings of the intima of medium to large sized elastic and muscular arteries. Arterial thrombosis on ruptured atherosclerotic plaques can lead to acute events, such as myocardial infarction (MI) and ischemic stroke. Platelets are the key cellular component of arterial thrombi with platelet adhesion under high shear conditions being central to atherothrombosis. In addition, platelets play a role in the progression of atherosclerosis. In this review, we will discuss the evidence for the role of platelets in atherothrombosis, notably the efficacy of antiplatelet agents in the prevention of ischemic events, and finally their role in the progression of atherosclerosis (atherogenesis).