Thrombosis and Acute Coronary Syndrome

Thrombosis superimposed on coronary atherosclerosis puts the heart in jeopardy

Coronary heart disease (CHD) is the term for atherosclerosis affecting the coronary arteries. It is the single most common cause of death in Europe, responsible for nearly two million deaths a year.³⁶ CHD is caused by atherosclerosis, a chronic process in which lipid-rich plaque forms in the arterial wall.⁵ Factors that increase a person’s risk of coronary heart disease include a family history of the condition, high cholesterol, high blood pressure, diabetes, and smoking.³⁷

Atherothrombosis

Acute coronary syndrome (ACS) is the acute manifestation of CHD. It occurs when a thrombus forms over an atherosclerotic plaque within a coronary artery, an event described as atherothrombosis.^{5, 23}

ACS comprises the following spectrum of life-threatening disorders²³:

Unstable angina: a worsening of angina symptoms caused by the formation of a thrombus that does not completely occlude the coronary artery and does not cause myocardial damage
Myocardial infarction (MI) without ST elevation (NSTEMI): similar to unstable angina but with signs of myocardial ischaemia on electrocardiogram and positive biomarkers
ST-elevation MI (STEMI): complete thrombotic occlusion of a coronary artery, leading to destruction of myocardial tissue without emergent intervention

Abnormalities of coagulation can continue after patients with ACS have been hospitalised. Recurrent thromboses, either in the coronary arteries or in other atherosclerotic arteries (eg, the carotids), could lead to recurrent ACS or stroke, respectively.^{28, 38, 39} For this reason, these patients are often treated with a combination of medications that target different facets of the coagulation process.

Coronary atherosclerosis, thrombosis

Virchow’s triad and acute coronary syndrome

The presence of coronary atherosclerosis is not the only abnormality in ACS patients that predisposes to thrombus formation. As with venous thromboembolism (VTE) and atrial fibrillation (AF), these other derangements are consistent with the factors that comprise Virchow’s triad for thrombosis formation.²⁵⁵ In ACS, these factors include:

Abnormal patterns of blood flow through the coronary arteries
Changes in the surface lining of the coronary arteries
Systemic factors, including inflammation and recurrent infection, that contribute to a sustained or intermittent hypercoagulable state²⁵⁵

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Article references

36 - British Heart Foundation. European Cardiovascular Disease Statistics, 2008. http://www.heartstats.org/datapage.asp?id=7683. Accessed March 8, 2008.
5 - Fuster V, Moreno PR, Fayad ZA, Corti R, Badimon JJ. Atherothrombosis and high-risk plaque: part I: evolving concepts. J Am Coll Cardiol. 2005;46(6):937-954.
37 - National Cholesterol Education Program, Third Report of the NCEP Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATPIII). National Cholesterol Education Program. National Institutes of Health, National Heart, Lung, and Blood Institute. NIH Publication No. 02-5215. September 2002.
23 - Bassand JP, Hamm CW, Ardissino D, et al; Task Force for Diagnosis and Treatment of Non-ST-Segment Elevation Acute Coronary Syndromes of European Society of Cardiology. Guidelines for the diagnosis and treatment of non-ST-segment elevation acute coronary syndromes. Eur Heart J. 2007;28(13):1598-1660.
28 - Lip GY, Blann AD. Thrombogenesis and fibrinolysis in acute coronary syndromes. Important facets of a prothrombotic or hypercoagulable state? J Am Coll Cardiol. 2000;36(7):2044-2046.
38 - Hurlen M, Abdelnoor M, Smith P, Erikssen J, Arnesen H. Warfarin, aspirin, or both after myocardial infarction. N Engl J Med. 2002;347(13):969-974.
39 - Gorelick PB. Epidemiology of transient ischemic attack and ischemic stroke in patients with underlying cardiovascular disease. Clin Cardiol. 2004;27(5)(suppl 2), II4-II11.
255 - Refludan [package insert]. Wayne, NJ: Bayer HealthCare Pharmaceuticals; 2007.

Acute coronary syndrome: This is an umbrella term used to cover any group of clinical symptoms compatible with acute myocardial ischaemia (chest pain due to insufficient blood supply to the heart muscle that results from coronary artery disease). Acute coronary syndrome covers the spectrum of clinical conditions ranging from unstable angina to STEMI and NSTEMI.
Angina: Heart condition characterised by intermittent chest pain. Angina usually results from coronary artery disease and may further be classified as stable or unstable angina. Stable angina refers to the more common understanding of angina related to myocardial ischemia. Unstable angina may occur unpredictably at rest which may be a serious indicator of an impending heart attack.
Venous thromboembolism: A condition in which a blood clot (thrombus) forms in a vein, which in some cases then breaks free and enters the circulation as an embolus, finally lodging in and completely obstructing a blood vessel, e.g., in lungs causing a PE. The term encompasses both DVT and PE.