A non-ST segment elevation myocardial infarction, also called an NSTEMI or a non-STEMI, is a type of heart attack. While it's less damaging to your heart than a STEMI, it's still a serious condition that needs immediate diagnosis and treatment.
What Causes a Non-ST Segment Elevation Myocardial Infarction?
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:
- A buildup of plaque on your coronary arteries
- Spasms in your coronary arteries (blood vessels that bring oxygen-rich blood to your heart)
- A blockage in a smaller coronary artery
- Inflammation in the wall of your coronary arteries
- Cardiac contusion (bruising of your heart muscles)
- Inflammation of your heart muscle
- Drugs that are toxic to your heart
- Low blood pressure
- High blood pressure
- Blood clot in your lungs
- Rapid heart rate
- Narrowing of your aortic valve opening, which helps control blood flow before it leaves your heart
What Are the Symptoms of a Non-ST Segment Elevation Myocardial Infarction?
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
- 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.
What Are the Risk Factors for a Non-ST Segment Elevation Myocardial Infarction?
Risk factors for all forms of acute coronary disease include:
How Is an NSTEMI Different From a STEMI?
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.
How Is a Non-ST Segment Elevation Myocardial Infarction Treated?
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:
- Your age
- Your heart rate
- Your systolic blood pressure, which is the top number when your blood pressure is measured.
- Your renal (kidney) function
- If you have congestive heart failure
- ST-segment change (based on your EKG)
- If you had heart failure when you got to the hospital
- If your blood tests show your heart is stressed (cardiac biomarkers)
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:
- Prevent your blood from clotting
- Thin your blood
- Relieve your chest pain
- Slow down your heart rate
- Lower your cholesterol
- Reduce swelling in your heart
- Block chemicals in your body that tighten your blood vessels
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.
Preventing a Non-ST Segment Elevation Myocardial Infarction
Lifestyle changes are an important part of preventing any type of acute coronary syndrome. Here are some things you can do to stay healthy: