What is the difference between STEMI and non-STEMI heart attacks?

A STEMI heart attack is defined by a change in the patient's EKG. Watch Roger Muse, MD, cardiac electrophysiologist with Metropolitan Methodist Hospital, explain how a STEMI heart attack is different than a non-STEMI heart attack. 

Both a STEMI and non-STEMI heart attack are equally dangerous. Learn how each type of heart attack is treated in this video from Alvin Haynes, MD, of Regional Medical Center of San Jose.

A STEMI or ST-elevation myocardial infarction is caused by a sudden complete (100%) blockage of a heart artery (coronary artery). A non-STEMI is usually caused by a severely narrowed artery but the artery is usually not completely blocked. The diagnosis is initially made by an electrocardiogram (ECG or EKG). In most situations, a patient having a STEMI needs to be treated immediately and this usually involves an emergent cardiac catheterization. A patient with a non-STEMI also often should undergo a cardiac catheterization but it may not have to be done immediately. Both types of heart attacks are serious and need prompt medical treatment.

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A STEMI heart attack is a serious form of heart attack. STEMI is the abbreviation for an “ST-elevation myocardial infarction.” A STEMI heart attack is identified by a test called an electrocardiogram that records the electrical activity of your heart. If this test shows something called “ST-elevation,” you are having a STEMI heart attack. This type of heart attack is typically caused by complete obstruction of a coronary artery - an artery that delivers blood to the heart. A STEMI needs to be recognized quickly and is best treated by emergency angioplasty and stenting.

Non-STEMI is a shorthand medical term for “non-ST-elevation myocardial infarction.” These types of heart attacks are often abbreviated as “NSTEMI.” While they may not be as serious as the STEMI heart attack, they are still heart attacks and result in heart muscle death. A non-STEMI heart attack does not show an elevated ST segment on an electrocardiogram.  A NSTEMI should also be recognized quickly and is best treated by medications and early angioplasty and stenting.