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Diagnosis of Heart Attack

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A heart attack requires immediate emergency medical care. If you think you are having a heart attack, call 911 immediately. At the emergency room, you will be hooked up to a cardiac (heart) monitor, so medical personnel can monitor your heart’s electrical activity. You will also undergo several different tests that will help the doctors to determine the appropriate treatments for you.

The following tests will likely be performed in the hospital:

Blood tests —Certain substances are found in the blood within hours or days after a heart attack. Blood tests will be repeated every 6-8 hours to track certain enzymes (eg, troponins, creatine kinase). Progressive elevation indicates heart muscle damage.

Urine tests —A sample of urine will reveal certain substances within hours or days after a heart attack.

Electrocardiogram (EKG) —This test records the heart's activity by measuring electrical currents through the heart muscle. Certain abnormalities in the EKG occur when there is significant blockage of the coronary arteries and/or damage to the heart muscle. The EKG will be repeated to track the progression of these changes.

Echocardiogram —High-frequency sound waves (ultrasound) are used to examine the size, shape, and motion of the heart. Echocardiograms can be performed using transducers held against the outside of the chest, or through a specialized transducer that is passed down the patient’s throat (transesophageal echocardiogram), allowing even better imaging of the heart and its blood vessels.

Coronary catheterization (angiography) —In this procedure, x-rays are taken after dye is injected into the arteries. This is performed as part of a cardiac catheterization to look for abnormalities in the arteries that supply blood to the heart. You will be awake but sedated during the procedure. It may cause some discomfort.

Other tests that may be ordered include:

Magnetic resonance imaging (MRI) —This test uses magnetic waves to make two- or three-dimensional pictures of the heart. It is not painful, however the test might be difficult for patients who are claustrophobic or very anxious. In this situation, a so-called “open MRI” might be indicated.

Nuclear scanning —Radioactive material (such as thallium) is injected into a vein and observed as it is absorbed by the heart muscle. The areas with diminished flow (and therefore uptake of the radioactive material) show up as dark spots on the scan. This test aids in determining heart function.

Computed Tomography Electron-beam CT scan (CT angiography) —This is a type of x-ray test that uses a computer to make detailed pictures of the heart, coronary arteries, and surrounding structures. This type of CT scan detects calcium deposits and cholesterol plaques in the coronary arteries. Based on this and other information, the doctor attempts to determine the risk of heart disease, including heart attacks. This test is not used to determine whether someone just had a heart attack. It can only be helpful in determining the risk of heart disease in some patients. The American Heart Association published guidelines in 2006, indicating those most likely to benefit from the procedure are patients at intermediate risk of coronary artery disease.

Stress test —This test records the heart's electrical activity under increased physical demand. Stress tests can also be combined with echocardiography or with nuclear scanning. Patients who cannot exercise may be given a medication intravenously that simulates the effects of physical exertion.

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  • Mayo Clinic Heart Center website. Available at: Accessed January 29, 2007.