STEMI Heart Attacks and Why They Are So Dangerous

This is the most severe type of heart attack

Table of Contents
View All
Table of Contents

ST-segment elevation myocardial infarction (STEMI) describes the most deadly type of heart attack. With a STEMI heart attack, the artery, or tube that carries blood from your heart to the rest of the body, is completely blocked. Parts of the heart that are supplied by this artery will then begin to die.

This article explains what a STEMI heart attack is. It also covers symptoms, diagnosis, and treatment options.

What Is a STEMI Heart Attack?

STEMI is the most severe type of acute coronary syndrome (ACS), which describes conditions where there is a rapid decrease of blood flow to the heart.

A STEMI heart attack occurs when:

  • A fatty substance called plaque builds up in the coronary arteries, which supply blood to the heart.
  • This stress triggers a tear in the artery, which blood clots, or clumps of blood, cover up.
  • This causes a complete blockage in the artery.
  • When blocked, the part of the heart muscle serviced by that artery will quickly suffer from a lack of oxygen, also known as ischemia.
  • Some of the heart muscle will begin to die resulting in a myocardial infarction, or heart attack.

Why It's Called a STEMI Heart Attack

It is called a STEMI heart attack because of a pattern that forms on a medical test called an electrocardiogram (ECG). This diagnostic test uses sensors to monitor the heart.

The "ST-segment" refers to a part of the test that shows the heart's activity in a wave pattern. When a person has the most severe type of heart attack, this segment will appear abnormally elevated, instead of flat. This indicates a total blockage.

STEMI vs. NSTEMI vs. Unstable Angina

Other, less severe, types of ACS are notably different from the STEMI type. They include:

  • Unstable angina: With this type of ACS, blood clots will form, dissolve, and re-form without causing a fixed blockage. When this happens, an individual may have random chest pain, even when resting.
  • Non-ST-segment elevation myocardial infarction (NSTEMI): This occurs when the blockage doesn't completely stop the blood flow in a major artery or totally blocks a minor artery. It may be called a "partial heart attack."
Types of Acute Coronary Syndrome

 Verywell / JR Bee

Symptoms of a STEMI Heart Attack

Symptoms can vary from person to person. Some STEMI symptoms may include: 

  • Pain around the shoulder blades, arm, chest, jaw, left arm, or upper stomach
  • Pain or pressure around chest area, also known as angina
  • Sweating, or feeling out of breath
  • Discomfort or tightness in the neck or arm
  • Indigestion, which is discomfort in the stomach and chest
  • Heartburn, which describes when you have an acidic taste in your mouth and upper chest discomfort
  • Nausea and vomiting
  • Fatigue or sudden exhaustion
  • Dizziness
  • Increased or irregular heart rate

Anyone who is at risk of a heart attack should pay close attention to any unusual symptoms and seek medical attention right away if any are noticed.

Symptoms of ST-segment elevation myocardial infarction (STEMI).
Verywell / Laura Porter

How This Condition Is Diagnosed

To diagnose a STEMI, a healthcare provider will go over your symptoms. They will also run diagnostic tests like an ECG, or magnetic resonance imaging (MRI), which creates a detailed image of your heart. In addition, your healthcare provider may also run blood tests, known as cardiac biomarkers, to check for heart muscle damage.

STEMI Treatment

Because a STEMI is a severe heart attack, treatment will begin as soon as possible. Keep in mind, the longer it takes to unblock the artery, the more damage there may be. 

Treatment may include:

After treatment, the recovery period begins. This may include an exercise-based rehabilitation program, dietary changes, and the use of medications like blood thinners, which prevent blood clots.

STEMI Heart Attack Prognosis

STEMI is the most deadly type of heart attack. Mortality rates, or the amount of people who die due to this type of heart attack, differ by the location of the blockage.

  • Anterior STEMI mortality rate: 21.4%
  • Inferior localized STEMI mortality rate: 12.2% 

Other factors that increase the risk of death from STEMI include history of:

  • A prior heart attack
  • Hypertension
  • High cholesterol
  • Diabetes
  • Heart failure
  • Smoking

In addition, the older a person is, the more likely STEMI will be fatal. Research shows people age 80 and older have a 45.9% mortality rate from STEMI.


STEMI is the most severe type of acute coronary syndrome. With this type of heart attack, there is a complete blockage in one of the coronary arteries.

Symptoms of a STEMI may vary from person to person, but generally include discomfort, pain, or pressure around the chest area.

To diagnose a STEMI, your healthcare provider will go over your symptoms, as well as run various diagnostic tests. Treatment will begin as soon as possible and may include various medications and procedures to help unblock the artery and reduce discomfort.

Frequently Asked Questions

  • Can you survive a STEMI heart attack?

    Yes, provided you get prompt medical attention. Treatment may include blood thinners such as aspirin, oxygen therapy, and surgery. Surgical treatments for STEMI include angioplasty and stenting. 

  • Which is worse, a STEMI or non-STEMI heart attack?

    While all heart attacks are serious and potentially deadly, STEMI heart attacks are the most lethal because they cause a total (rather than partial) blockage in an artery of the heart. However, the five-year survival rates are higher for STEMI (77%) than non-STEMI (51%).

  • How long can you live after a STEMI heart attack?

    Individuals who survive past the year mark have a life expectancy similar to the general population.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Acute coronary syndrome.

  2. MedlinePlus. Unstable angina.

  3. Vasiljević Z, Stojanović B, Kocev N, et al. [Hospital mortality trend analysis of patients with ST elevation myocardial infarction in the Belgrade area coronary care units]. Srp Arh Celok Lek. 2008;136 Suppl 2:84-96. Serbian. doi:10.2298/sarh08s2084v

  4. Basit H, Malik A, Huecker MR. Non ST Segment Elevation Myocardial Infarction. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022.

  5. Snorrason EL, Johannnesdottir BK, Aspelund T, Gudnason V, Andersen K. [Long-term survival of patients with acute myocardial infarction in Iceland]. Laeknabladid. 2018;104(11):491-497. Icelandic. doi:10.17992/lbl.2018.11.203

  6. Pascual I, Hernandez-Vaquero D, Almendarez M, et al. Observed and expected survival in men and women after suffering a stemiJ Clin Med. 2020;9(4):E1174. doi:10.3390/jcm9041174