Bayer Pharma AG

Essence of this Article

Acute coronary syndrome (ACS), a common complication of coronary heart disease, is associated with more than 2.5 million hospitalizations worldwide each year. Most cases of ACS are caused by rupture of an atherosclerotic plaque in a coronary artery, resulting in the formation of a thrombus, which can restrict the flow of blood to the heart muscle. The degree of arterial blockage caused by the thrombus determines the amount of myocardial damage that occurs and the type of ACS that results. The main methods used to confirm a diagnosis of ACS and identify the type of ACS include electrocardiogram (ECG) and cardiac troponins. Acute phase treatment of ACS includes a combination of anti-ischaemic and antithrombotic agents.

Acute coronary syndrome: a leading cause of mortality

Coronary artery with thin muscular media and prominent intimal hyperplasia with calcification. Lumen obstructed by thrombus (arrow).

Coronary artery with thin muscular media and prominent intimal hyperplasia with calcification. Lumen obstructed by thrombus (arrow).







Coronary heart disease is the most common cause of death in the United States (US) and Europe.543, 215 ACS, a common complication of coronary heart disease, is associated with more than 2.5 million hospitalizations worldwide each year.{216) ACS describes clinical disorders ranging from ST-elevation myocardial infarction (STEMI) to non-ST-elevation myocardial infarction (NSTEMI) and unstable angina (UA).217 It is estimated that a myocardial infarction (MI) occurs every 34 seconds in the US, and that every 83 seconds one person dies from a major coronary event.544

Most cases of ACS are caused by rupture of an atherosclerotic plaque in a coronary artery, resulting in the formation of a thrombus.219 When plaques erode or rupture, the resulting thrombus restricts the flow of blood to the heart muscle.217, 220 A prolonged lack of blood supply resulting in necrosis of heart muscle tissue is defined as a MI.217

An area of cardiac muscle damage caused by acute occlusion in a coronary artery that delivers blood to that area.

An area of cardiac muscle damage caused by acute occlusion in a coronary artery that delivers blood to that area.

Plaque rupture results in exposure of the contents of the plaque and subendothelial fibres to the blood, leading to the activation of platelets, which in turn adhere to subendothelial structures. Aggregation of additional platelets causes the thrombus to grow. At the same time, the coagulation cascade is activated, 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.219

The degree of arterial blockage caused by the thrombus determines the amount of myocardial damage that occurs and the type of ACS that results:216, 217

  • UA – partial/intermittent occlusion, no myocardial damage
  • NSTEMI – partial/intermittent occlusion, myocardial damage
  • STEMI – complete occlusion, myocardial damage
Illustration of normal ECG and ECGs showing STEMI and NSTEMI.

Illustration of normal ECG and ECGs showing STEMI and NSTEMI. ECG, electrocardiogram; NSTEMI, non-ST-elevation myocardial infarction; STEMI, ST-elevation myocardial infarction; UA, unstable angina.

Diagnosis of ACS

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:221

  • 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 – elevated as a result of myocardial damage, can be used to distinguish UA from NSTEMI
Diagnosing the spectrum of ACS.

Diagnosing the spectrum of ACS.{221} ACS, acute coronary syndrome; ECG, electrocardiogram; NSTEMI, non-ST-elevation myocardial infarction; STEMI, ST-elevation myocardial infarction.

Acute phase treatment of ACS

Acute phase treatment of ACS includes a combination of anti-ischaemic and antithrombotic agents, with coronary reperfusion achieved using fibrinolysis and/or revascularization (percutaneous coronary intervention or coronary artery bypass graft surgery).217, 221, 222

During an ACS event, platelets become activated and thrombin is generated, leading to potentially life threatening coronary artery occlusion.223, 224 Antiplatelet and anticoagulant agents are routinely used during the acute phase of ACS treatment, for example:217, 221

  • Antiplatelets – acetylsalicylic acid, P2Y225 inhibitors (e.g. clopidogrel, ticagrelor, prasugrel)
  • Anticoagulants – unfractionated heparin, low molecular weight heparins, bivalirudin, fondaparinux

Where to next?

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Graham Turpie