What Is a Non-ST Segment Elevation Myocardial Infarction?

Medically Reviewed by James Beckerman, MD, FACC on May 15, 2023
4 min read

A non-ST segment elevation myocardial infarction, also called an NSTEMI or a non-STEMI, is a type of heart attack. While it's often less damaging to your heart than a STEMI, it's still a serious condition that needs immediate diagnosis and treatment. 

An NSTEMI is a type of acute coronary syndrome (ACS). ACS happens when your heart needs more oxygen than it's getting. Since blood carries oxygen to your heart, anything that limits the flow of blood can cause an NSTEMI. These causes can include: 

Symptoms of an NSTEMI can include:

  • Pressure or heaviness in your chest
  • Chest tightness or discomfort
  • Trouble breathing
  • Pain or irritation in your neck or jaw
  • Pain or irritation in your stomach or back
  • Nausea
  • Lightheadedness or dizziness
  • Unexplained sweating 

You should call 911 or go to an emergency room immediately if you are experiencing any symptoms of a heart attack. The faster you get treatment, the less damage there is to your heart. 

Risk factors for all forms of acute coronary disease include: 

Both STEMI and NSTEMI are types of acute coronary syndrome. ACS includes three subtypes. These subtypes are based on the amount and type of blockage and the result of diagnostic tests.

STEMI. This is the most severe form of ACS. It happens when there is a complete blockage in one of your heart's major coronary arteries. It's a life-threatening emergency. It will show up as an abnormality on an electrocardiogram (EKG).  

NSTEMI. In this form of ACS, your heart is getting some oxygen but not enough. It may be caused by any of the conditions listed above. An NSTEMI is diagnosed when your EKG does not show the type of abnormality seen in a STEMI but your blood tests show that your heart is stressed. 

Unstable angina. This is the least severe type of ACS. It can be caused when a blood clot blocks a coronary artery partially or totally. The blood clot may then dissolve and form again. You may have pain (angina) each time a clot forms. Unstable angina may be diagnosed when your EKG doesn't show abnormalities and your blood doesn't show evidence of your heart being stressed. 

The treatment for your NSTEMI will depend on the severity of it, your risk factors, and your medical history. Your doctor will give you a GRACE risk score, which will help evaluate the severity of your STEMI and help guide your treatment plan. The GRACE risk score, which stands for Global Registry of Acute Coronary Events, is based on: 

Based on your GRACE risk score, you will either be low, medium, or high risk. 

Low risk. If you are rated low risk, your doctor will likely prescribe medication. These may include medications that: 

Medium or high risk. If you are rated medium or high risk, your doctor may suggest surgery to open your blocked arteries or to bypass the blocked artery. 

Lifestyle changes are an important part of preventing any type of acute coronary syndrome. Here are some things you can do to stay healthy: