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Heart Attacks - STEMI vs. NSTEMI

Vijayarani Sivakumar

Published On - November 01, 2021

Overview

A heart attack, or myocardial infarction, is a medical emergency in which the supply of blood to the heart is suddenly and severely reduced or cut off, causing the muscle to die from lack of oxygen. More than 1.1 million people experience a heart attack (myocardial infarction) each year, and for many of them, the heart attack is their first symptom of coronary artery disease. A heart attack may be severe enough to cause death or it may be silent. As many as one out of every five people have only mild symptoms or none at all, and the heart attack may only be discovered by routine electrocardiography done some time later.

Causes and Risk Factors

A heart attack (myocardial infarction) is usually caused by a blood clot that blocks an artery of the heart. The artery has often already been narrowed by fatty deposits on its walls. These deposits can tear or break open, reducing the flow of blood and releasing substances that make the platelets of the blood sticky and more likely to form clots. Sometimes a clot forms inside the heart itself, then breaks away and gets stuck in an artery that feeds the heart. A spasm in one of these arteries can cause the blood flow to stop.

Diagnosis

Because a heart attack (myocardial infarction) can be life threatening, men older than 35 or women older than 50 who have chest pain should be examined to see if they are having a heart attack. However, similar pain can be caused by pneumonia, a blood clot in the lung (pulmonary embolism), pericarditis, a rib fracture, spasm of the esophagus, indigestion or chest muscle tenderness after injury or exertion. A heart attack can be confirmed within a few hours of its occurrence by:

Electrocardiography (ECG)

Blood tests to measure levels of serum markers. The presence of these markers shows that there has been damage to or death of the heart muscle. These markers are normally found in the heart muscle, but they are released into the blood when the heart muscle is damaged.

Echocardiography can be performed if the above tests do not give enough information

Radionuclide imaging can also be done

Acute coronary syndrome and heart attacks

Acute coronary syndrome (ACS) is when the arteries that carry blood, oxygen, and nutrients get blocked. Heart attacks are a form of ACS. They occur when your heart doesn’t get enough blood supply. A heart attack is also known as a myocardial infarction.

The three types of heart attacks are:

• ST segment elevation myocardial infarction (STEMI)
• non-ST segment elevation myocardial infarction (NSTEMI)
• coronary spasm, or unstable angina

“ST segment” refers to the pattern that appears on an electrocardiogram, which is a display of your heartbeat. Only a STEMI will show elevated segments. Both STEMI and NSTEMI heart attacks can cause enough damage to be considered major heart attacks.

Read on to learn more about each type of heart attack, as well as information on prevention, treatment, and recovery.

STEMI: The classic or major heart attack

When most people think of a heart attack, they often think of a STEMI. A STEMI occurs when a coronary artery becomes completely blocked and a large portion of the muscle stops receiving blood. It’s a serious heart attack that can cause significant damage.

Symptoms and signs of a STEMI

A STEMI has the classic symptom of pain in the center of the chest. This chest discomfort may be described as a pressure or tightness rather than a sharp pain. Some people who experience STEMIs also describe feeling pain in one or both arms or their back, neck, or jaw.

Other symptoms that may accompany chest pain include:

• nausea
• shortness of breath
• anxiety
• lightheadedness
• breaking out in a cold sweat

NSTEMI heart attacks

Unlike in a STEMI, the affected coronary artery is only partially blocked in a NSTEMI. A NSTEMI won’t show any change in the ST segment on the electrocardiogram.

A coronary angiography will show the degree to which the artery is blocked. A blood test will also show elevated troponin protein levels. While there may be less heart damage, an NSTEMI is still a serious condition.

CAS, silent heart attack, or heart attack without blockage

The coronary artery spasm is also known as a coronary spasm, unstable angina, or silent heart attack. The symptoms, which can be the same as a STEMI heart attack, may be mistaken for muscle pain, indigestion, and more. It occurs when one of the heart’s arteries tightens so much that blood flow stops or becomes drastically reduced. Only imaging and blood test results can tell your doctor if you’ve had a silent heart attack.