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Peripheral Artery Disease: causes and consequences

Coronary Artery Disease: causes and consequences

Acute Coronary Syndrome

This section introduces ACS and covers the diagnosis of the condition

Coronary heart disease is the most common cause of death in the US and Europe,1,2 with ACS being a frequent complication of this disease.


ACS is an umbrella term encompassing the following clinical disorders:3

  • UA


It is estimated that an MI, commonly referred to as a heart attack, occurs every 40 seconds in the US, with 14% of these occurrences resulting in death.4


Most cases of ACS are caused by the erosion or rupture of an atherosclerotic plaque, a thickening of the vessel wall in a coronary artery.5


Plaque rupture results in exposure of the contents of the atherosclerotic plaque and subendothelial fibres to the blood, leading to:3,5,6

  • Thrombus formation
  • Platelet activation and adherence to subendothelial structures; aggregation of additional platelets causes the thrombus to grow
  • Activation of the coagulation cascade, resulting in the production of thrombin, which stimulates further platelet recruitment and aggregation. Thrombin also catalyses the generation of fibrin, which forms the main protein component of the thrombus


The thrombus restricts the flow of blood to the heart. A prolonged lack of blood supply resulting in necrosis (death) of heart muscle tissue is defined as an MI.3 The degree of arterial blockage caused by the thrombus determines the amount of myocardial damage that occurs and the type (and severity) of ACS that results:3,7

  • UA – partial/intermittent occlusion, no myocardial damage
  • NSTEMI – partial/intermittent occlusion, myocardial damage
  • STEMI – complete occlusion, myocardial damage
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Coronary artery with thin muscular media and prominent intimal hyperplasia with calcification. Lumen obstructed by thrombus (arrow)

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Cardiac muscle damage in ACS. An area of cardiac muscle damage due to acute occlusion in a coronary artery that delivers blood to that area

Patients with ACS typically present with acute chest pain. The main methods used to confirm a diagnosis of ACS and to distinguish between the three types of ACS are as follows:8


ECG: UA and NSTEMI are associated with ST depression/transient elevation and/or T-wave changes; persistent ST elevation is characteristic of STEMI

  • Cardiac troponins: Troponin levels are sensitive markers of myocardial injury; elevated troponin levels as a result of myocardial damage can be used to distinguish UA from NSTEMI
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Illustration of normal ECG and ECGs showing STEMI and NSTEMI

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Diagnosing the spectrum of ACS8


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