Essence of this Article

When a thrombus forms within an artery, this is known as an arterial thrombosis. Arterial thrombi usually develop on top of an atherosclerotic plaque and cause myocardial infarction (MI), unstable angina, ischaemic stroke and some manifestations of peripheral arterial disease, such as acute limb ischaemia. Risk factors for arterial thrombosis include smoking, obesity, high blood pressure, increasing age, diabetes and family history. The incidence and prevalence of the clinical manifestations of arterial thrombosis is high. The annual incidence of symptomatic and fatal MI and stroke in the United States (US) in 2010 has been calculated to be 915,000 and 795,000 cases, respectively.

Arterial Thrombi

coronary bypass thrombosis pathology

Coronary thrombosis.

When a thrombus forms within an artery, this is known as an arterial thrombosis.

  • In the arteries, clot formation is typically triggered by the rupture of an atherosclerotic plaque, a highly thrombogenic event, with platelets rapidly recruited to the site. The fibrin content of the clot slowly increases as the thrombus extends into the arterial lumen. Thus, an arterial thrombus is typically platelet-rich, fast growing and exposed to fast blood flow25, 36
  • Arterial-type clots can result in MI and unstable angina (acute coronary syndrome events),559 ischaemic stroke560 and some manifestations of peripheral arterial disease, such as acute limb ischaemia561
  • Atrial fibrillation-related thrombi are also categorised as arterial clots, but more closely resemble ‘venous-type’ clots, fulfilling the Virchow’s triad for thrombogenesis. Atrial fibrillation-related thrombi form in low-flow, low-pressure environments, producing slow growing, fibrin-rich clots36, 562
  • Thrombi characteristics are an important consideration for the development of treatment/prevention strategies (i.e. anticoagulant/antiplatelet)25, 36

Risk factors

Important risk factors for atherosclerosis and arterial thrombosis include:563

  • Smoking
  • Obesity
  • High blood pressure
  • Increased levels of cholesterol
  • Diabetes
  • Increasing age
  • Family history
  • Physical inactivity
  • Increased concentrations of blood coagulation factors
  • Blood serum lipid abnormalities

Incidence and prevalence

Atherosclerosis leads to cardiovascular disease, which is the leading cause of death in industrialized countries. Atherosclerotic lesions develop throughout the arterial system and, depending on the vascular bed most affected, disease can manifest as coronary artery disease (CAD), peripheral artery disease (PAD) or cerebrovascular disease. CAD is the most commonly diagnosed form of cardiovascular disease. In CAD, atherosclerosis damages the coronary artery wall predisposing to thrombus formation. The symptoms and severity of acute coronary syndromes (unstable angina and MI) vary depending on the degree to which thrombi occlude the coronary arteries.32, 559

The incidence and prevalence of the clinical manifestations of arterial thrombosis is high. The annual incidence (number of new and recurrent cases per year) of symptomatic or fatal MI and stroke in the US in 2010 has been estimated to be 915,000 and 795,000, respectively. Estimates place the overall prevalence in the US of MI at 7.6 million and stroke at 6.8 million.564