Cardiac Enzymes (Cardiac Biomarkers)

What are cardiac enzymes (cardiac biomarkers)?

When your heart experiences damage or stress due to lack of oxygen, it releases substances called cardiac enzymes into the bloodstream.

What are enzymes?

Enzymes are proteins that help your body manage metabolism and other chemical processes. Thousands of types of enzymes perform specialized functions, like:

• Blood clotting.
• Brain, spine and nerve function.
• Breathing.
• Digestion.
• Musculoskeletal movements.
• Removing waste from your body through urination.

What is a cardiac enzyme marker test?

An enzyme marker test is a blood test to measure specific biological markers (biomarkers) in your blood. High (elevated) levels of cardiac enzymes can be a sign of a heart attack or another heart problem. Cardiac enzymes are also called cardiac biomarkers.

How do healthcare providers use cardiac biomarkers?

Cardiac biomarkers help healthcare providers know if symptoms are due to a heart attack (myocardial infarction), angina, heart failure or another problem.

Increases in cardiac enzymes can also indicate acute coronary syndrome (ACS) or myocardial ischemia.

Treatments for these conditions vary. An accurate diagnosis is critical to ensuring you receive the appropriate care.

What’s the purpose of cardiac biomarkers?

Healthcare providers measure cardiac marker levels to:

• Screen for heart damage and other problems.
• Diagnose heart conditions that cause symptoms such as chest pain, angina and shortness of breath.
• Monitor how well heart medications and heart surgery work.

Where do you get a cardiac enzyme marker test?

A cardiac enzyme marker test requires a blood draw. The blood draw takes just a few minutes. In an emergency situation, the blood draw takes place in the emergency department or hospital. For non-urgent situations, the test may take place at your healthcare provider’s office or a blood-testing lab.

What are the types of cardiac enzymes (cardiac biomarkers)?

There are different types of cardiac biomarkers. All of them are enzymes or proteins. Elevated heart enzymes may show that you have cardiovascular disease or other heart problems.

Because the heart is the only organ that makes troponin, a biomarker test for this enzyme is the primary test healthcare providers use to detect heart damage from a heart attack or ACS. Troponin levels can rise for up to 12 hours after a heart attack. They stay elevated for up to two weeks. You may get several cardiac enzyme tests spaced several hours or days apart to measure these biomarkers.

Healthcare providers may also test for:

• Creatinine phosphokinase (CPK) and myoglobin (MB) help healthcare providers measure heart damage from a heart attack. Some labs reference CPK as creatinine kinase (CK). CPK or CK is known as the “muscle enzyme.” You may also see the two enzymes written as CPK-MB or CK-MB.
• Ischemia-modified albumin (IMA) can be a sign of myocardial ischemia. This blood flow problem in your heart can occur due to coronary artery disease (CAD) or coronary spasm. Healthcare providers usually order an IMA test along with an electrocardiogram (ECG or EKG) to confirm or rule out ACS.
• Peptides can signify stress on the heart from heart failure. Healthcare providers may test for natriuretic peptides (NPs). Or you may have tests for A-, B- or C-type atrial natriuretic peptide (ANP, BNP or CNP) or N-terminal proBNP (NT-proBNP).
• C-reactive protein (CRP), homocysteine and soluble CD40 ligand indicate heart inflammation, possibly from atherosclerosis. Your provider may look at CRP levels to gauge your risk of future heart problems.

Who needs a cardiac enzyme (cardiac biomarker) test?

Your healthcare provider may order a cardiac enzyme test if you have symptoms of a possible heart problem. These symptoms include:

• Chest pain.
• Dizziness.
• Nausea.
• Profuse sweating.
• Shortness of breath.

What is the normal range for cardiac enzymes (cardiac biomarkers)?

Heart enzyme results vary depending on the specific cardiac enzyme and test. The tests measure enzyme levels in nanograms per milliliter (ng/mL).

Most people who don’t have heart damage have troponin levels below 0.02 ng/mL. A higher number can point to severe heart damage.

Troponin and CPK levels can rise for up to 12 hours after heart damage occurs. For this reason, providers often order several cardiac enzyme tests spaced several hours apart.

What other blood tests do healthcare providers use to diagnose a heart attack or heart damage?

You may also get one or more of these blood tests:

• Complete blood count to measure blood cell and platelet levels.
• Basic metabolic panel or comprehensive metabolic panel to measure levels of electrolytes and proteins.
• Blood gas test to measure oxygen, carbon dioxide and acid levels.

What other tools do healthcare providers use to diagnose a heart attack or heart damage?

In addition to lab (blood) tests, you may receive:

• Chest X-ray.
• Echocardiogram, such as a transesophageal echocardiogram (TEE).
• Electrocardiogram (ECG or EKG).
• Exercise stress test or nuclear cardiac stress test.
• Angiogram.
• Positron emission tomography (PET) scan.

A note from Cleveland Clinic

Elevated levels of cardiac enzymes (cardiac biomarkers) in the blood are a sign of heart damage, stress or inflammation. Your heart releases these proteins after a heart attack. Your heart may also release cardiac biomarkers when low oxygen levels cause the heart to work harder than usual. An enzyme marker test (blood test) measures heart enzymes. Healthcare providers use cardiac biomarkers to diagnose, screen and treat heart conditions like acute coronary syndrome, coronary artery disease and atherosclerosis.