Elevated cardiac enzyme levels indicate when someone has experienced a heart attack. A cardiac enzyme test can measure the amount of cardiac enzymes in a person’s blood.

Certain enzymes are typically present in low quantities in the bloodstream. When a person’s cardiac enzyme levels are elevated, it can indicate that the heart muscle may be injured or may not be getting enough oxygen.

Read on to learn more about cardiac enzymes and the cardiac enzyme blood test. This article also discusses possible causes of elevated cardiac enzyme levels and what treatments may be necessary if someone has them.

Enzymes are proteins that the body produces to speed up specific chemical reactions. When an injury to the heart occurs, it releases certain enzymes.

Doctors measure cardiac enzymes to determine whether a person is having a heart attack, including troponin T (cTnT) and troponin I (cTnI).

Doctors will typically test for both cTnT and cTnl as these are the most specific enzymes to a heart attack. Doctors may also check the levels of creatine phosphokinase (CPK) in some situations.

A cardiac enzyme test is a blood test that measures the cardiac enzymes in the blood.

A healthcare professional inserts a needle into a person’s arm and draws a blood sample. They will then send the sample to the lab, where it undergoes analysis for cardiac enzymes.

People undergoing a cardiac enzyme test do not need to fast or undergo any special preparations. However, a person needs to let their doctor know if they take vitamin B7, or biotin, as it can make troponin levels appear lower.

Learn more about blood tests for a heart attack.

The results of a cardiac enzyme test can indicate if someone has experienced a heart attack.

Doctors and scientists measure troponin in nanograms per milliliter (ng/mL). The higher the number of nanograms per milliliter within the blood, the greater the likelihood of a heart attack.

The upper limit for troponin levels is 0.04 ng/mL. If a person’s cardiac enzyme test comes back positive for troponin above 0.04 ng/mL, they have likely had a heart attack or injury to the heart.

The results of a cardiac enzyme test can also help doctors assess the level of damage due to a heart attack. Generally, the more troponin in the blood, the more damage to the heart.

A cardiac enzyme test may come back typical if the test happens too soon after an injury to the heart. A doctor will generally repeat a cardiac enzyme test around 4–9 hours after the suspected injury or heart attack. However, in some cases, a high-sensitivity troponin may be possible earlier than this.

Learn more about troponin levels.

Aside from a heart attack, there are a few other factors that may cause cardiac enzyme levels to be elevated.

These include:

If a person has elevated cardiac enzymes, treatments will focus on the underlying cause.

A doctor will likely order other tests besides a cardiac enzyme test. This is because other factors besides heart attacks can cause high cardiac enzyme levels.

These tests may include the following:

If a doctor determines that a heart attack has caused elevated cardiac enzyme levels, the person will require treatment in the hospital with medications or surgery to restore blood flow to the heart.


Doctors may also prescribe the following medications for a person who has had a heart attack:

A doctor may recommend surgery in addition to medications for those who have just had a heart attack. Doctors may also suggest coronary stenting or coronary artery bypass surgery.

Learn more about medications a doctor may prescribe after a heart attack.

Coronary stenting

During this procedure, a doctor will guide a long, thin tube through an artery to find blockages. When the doctor locates a blockage, they will use a tool on the end of the tube to open the blocked artery and insert a metal stent to keep the artery open.

The person who had the heart attack is typically awake or under light sedation. People require less recovery time after this procedure than after a coronary bypass.

Coronary artery bypass

A coronary artery bypass is a major surgery that may occur immediately following a heart attack or shortly after to give the heart a chance to recover.

During a coronary artery bypass, the surgeon attaches the blood vessel to the artery to restore blood flow to the heart.

If a person has had a heart attack, they will typically have elevated cardiac enzymes. Blood tests, typically to check troponin enzyme levels, can help determine if a person has had a heart attack.

However, a doctor will usually order other tests alongside cardiac enzyme tests to assist in reaching an accurate diagnosis.

Aside from heart attacks, other conditions can cause elevated cardiac enzymes. These can include pulmonary hypertension, tachycardia, congestive heart failure, and kidney disease. It can also be the result of weakening or injury to the heart muscle, prolonged exercise, open heart surgery, and cardiac ablation.

A person’s doctor can advise on whether they order a cardiac enzyme test and what the individual can expect.