Heart Attack: An Acute Coronary Syndrome

Acute Coronary Syndrome is a name given to three types of coronary artery disease that are associated with sudden rupture of plaque inside the coronary artery:

  • Unstable angina
  • Non-ST segment elevation myocardial infarction or heart attack (NSTEMI)
  • ST segment elevation myocardial infarction or heart attack (STEMI).

The location of the blockage, the length of time that blood flow is blocked and the amount of damage that occurs determines the type of acute coronary syndrome. These life-threatening conditions require emergency medical care.

Unstable Angina

Unstable angina is a new symptom or a change from stable angina. The angina may occur more frequently, occur more easily at rest, feel more severe, or last longer. Although this angina can often be relieved with oral medications, it is unstable and may progress to a heart attack. Usually more intense medical treatment or a procedure is required. Unstable angina is an acute coronary syndrome and should be treated as a medical emergency.

Heart attack: Non-ST segment elevation myocardial infarction (NSTEMI)

This heart attack, or MI, may not cause changes on an electrocardiogram (ECG). However, chemical markers in the blood indicate that damage has occurred to the heart muscle. In NSTEMI, the blockage may be partial or temporary, and so the extent of the damage relatively small.

Heart attack: ST segment elevation myocardial infarction (STEMI)

This heart attack, or MI, is caused by an abrupt and prolonged blocked blood supply. It affects a large area of the heart muscle, and so causes changes on the ECG as well as in blood levels of key chemical markers.

Other terms associated with a heart attack:

Stunned Myocardium

If blood flow is returned to an area of heart muscle after a period of ischemia (lack of blood supply), the heart muscle may not pump normally for some time. This is called "stunned" heart muscle or myocardium.

Hibernating Myocardium

If deprived of adequate blood supply for a long period of time, some areas of heart muscle stop working as they should. Some areas will have permanent damage. Other areas are able to return to their normal function if blood flow is returned to that area (by medications or a procedure). Hibernating myocardium is heart muscle that is "resting" or "sleeping" and may possibly return to normal function if treated appropriately.

Cleveland Clinic cardiologists specialize in prompt diagnosis and treatment of heart attack and acute coronary syndromes. If you do not find what you are looking for about heart attacks, contact us. We would be happy to help you.

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