Cardiac Enzymes (Cardiac Biomarkers)

Cardiac Enzymes

Cardiac enzymes Your heart releases (cardiac biomarkers) when there’s heart damage or stress due to low oxygen. Troponin and creatinine phosphokinase (CPK) levels rise after a heart attack. Elevated heart enzyme levels can also indicate acute coronary syndrome or ischemia. Healthcare providers use enzyme marker tests (blood tests) to measure cardiac enzymes.

Does this test have other names?

CK, CK-MB, cardiac troponin T, troponin I, myoglobin, cardiac enzymes

Does this test have other names? CK, CK-MB, cardiac troponin T, troponin I, myoglobin, cardiac enzymes

A cardiac enzyme test is one tool doctors use to see if you’re having — or already had — a heart attack. You might also get the test if you have symptoms of a blockage in your heart’s arteries such as:

What Is a Cardiac Enzyme Test?

• Chest pain or pressure
• Dizziness
• Feeling very weak or tired
• Shortness of breath
• Sweating and cool, clammy skin
• Throwing up or feeling like you need to

Severe stress on the heart can damage its muscle. When that happens, your heart releases certain enzymes — a kind of protein — into your blood.

After a heart attack, the level of these enzymes can get pretty high. So checking them is a good way for your doctor to know something serious is going on.

A cardiac enzyme test does just that. Your doctor might want to measure your enzymes to figure out what’s happening with your heart.

Your doctor will most likely test for an enzyme called troponin. It goes into your blood soon after a heart attack. It stays at high levels even after other enzymes have gone back to normal.

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.

If your doctor suspects that you’re having a heart attack or that you may have had one recently or have other damage to the heart due to inflammation (myocarditis), they may recommend a cardiac enzyme test. This test measures the level of certain proteins circulating in your bloodstream. Such a test allows the doctor to confirm your diagnosis and start treatment ASAP.

After a heart attack, levels of troponins T and I may start to increase within around 4 hours. They’ll stay high for several days, meaning that they’re useful for indicating a heart attack.

After a heart attack, levels of troponins T and I may start to increase within around 4 hours. They’ll stay high for several days, meaning that they’re useful for indicating a heart attack.

Why do I need this test?

You may need this test if your healthcare provider thinks you’re having or have recently had a heart attack. You may also need this test if you have symptoms of coronary artery blockage.

You may need this test if your healthcare provider thinks you’re having or have recently had a heart attack. You may also need this test if you have symptoms of coronary artery blockage

Symptoms of coronary blockage may include:

• Chest pain or pressure that lasts for more than a few minutes
• Pain or discomfort in your shoulders, neck, arms, or jaw
• Chest pain that gets worse
• Chest pain that doesn’t get better by rest or by taking nitroglycerin

Other symptoms that may happen along with chest pain may include:

• Sweating, cool, clammy skin, or paleness

• Shortness of breath
• Nausea or vomiting
• Dizziness or fainting
• Unexplained weakness or extreme tiredness (fatigue)
• Fast or irregular pulse

What other tests might I have along with this test?

You may need other tests to measure other factors in your blood, or in your heart, or both. These include:

• Blood gases or other tests to measure oxygen in the blood
• Complete blood count (CBC)
• Electrolytes (sodium, potassium, chloride)
• Blood lipids (cholesterol and triglycerides)
• Blood sugar (glucose)
• Electrocardiogram (ECG)
• Echocardiogram or ultrasound of the heart muscle
• Cardiac catheterization or coronary angiogram
• B-type natriuretic peptide (BNP). This is to find stress in the heart or heart failure after a heart attack.

What your doctor may ask

Your doctor should also know any other important medical information, including:

• any previous heart disease or stroke history
• whether you have high blood pressure
• any recent surgeries or other procedures
• how long symptoms have been occurring
• whether you have kidney problems

A blood test for cardiac enzymes is similar to a standard blood test. The healthcare professional inserts a needle into your arm and draws enough blood to fill a small vial or two. You might feel a little pain during the insertion of the needle.

Your doctor will assess your biomarker levels to confirm whether you’ve had a heart attack and assess the extent of damage to the heart muscle. They’ll often check levels more than once to see if they change over time.

As well as checking your biomarkers, your doctor may also want to test your blood for other markers that give information about your heart and health status

This includes your:

• cholesterol levels
• blood glucose (sugar) levels
• white and red blood cell count, as well as your platelet levels
• your levels of electrolytes, such as sodium and potassium
• your kidney function
• levels of B-type natriuretic peptide (BNP), a hormone that can indicate heart failure

Possible side effects and complications

A cardiac enzyme test is relatively simple and painless. You may have some minor bruising or temporary soreness at the site where the needle is inserted to draw blood.

Be sure to tell the person drawing your blood if you have an allergy to latex. This can help you avoid complications. Otherwise, the test is safe and mostly risk-free.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in nanograms per milliliter (ng/mL). People who are young and healthy often have little or no cardiac troponin in their blood. Troponin I levels are often less than 0.12 ng/mL. Troponin T levels are often less than 0.01ng/mL.

Normal-level results vary. But cardiac troponin levels above the 99th percentile of the reference range suggest heart muscle damage and a heart attack.

Can other factors skew the results?

Cardiac enzyme levels can rise for reasons other than a heart attack. For example, sepsis, a type of blood infection, can lead to elevated troponin levels. The same is true for atrial fibrillation, a common heart rhythm problem. Other factors that could affect your test results include:

• A blood clot in the lungs
• acute or chronic heart failure
• amyloidosis
• brain injury
• cardiac contusion due to a chest wall injury
• cardioversion to treat atrial fibrillation or atrial flutter
• chemotherapy treatments
• coronary angioplasty
• defibrillation for ventricular fibrillation or tachycardia
• end-stage kidney disease
• myocarditis or myopericarditis
• open heart surgery
• other heart conditions, such as cardiomyopathy
• radiofrequency catheter ablation of arrhythmia
• rhabdomyolysis
• strenuous exercise
• valvular heart disease

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

Other factors aren’t likely to affect your results.

How do I get ready for this test?

You don’t need to get ready for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don’t need a prescription and any illegal drugs you may use.