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Cardiac Sarcoidosis: Diagnosis

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This information was reviewed and approved by Howard D. Weinberger, MD, FACC (3/1/2021).

How Is Cardiac Sarcoidosis Diagnosed?

Diagnosing cardiac sarcoidosis can be very challenging, because the symptoms of cardiac sarcoidosis are similar to those of many other diseases. Since cardiac sarcoidosis is relatively rare, many times other diseases are suspected instead of cardiac sarcoidosis.

There are no widely accepted guidelines for either screening or diagnosing sarcoidosis of the heart. Moreover, the currently available diagnostic tests are variable in their ability to detect cardiac sarcoidosis. Because of the devastating nature of cardiac sarcoidosis, most people with other forms of sarcoidosis are screened for sarcoidosis of the heart. This is done because it is rare that cardiac sarcoidosis occurs without another form of sarcoidosis. About one in four people with another form of sarcoidosis will have cardiac sarcoidosis as well; some say that number is even higher.

Initial cardiac evaluation of cardiac sarcoidosis may include:

  • Electrocardiogram (EKG). This test checks for an abnormal heart rhythm or abnormalities in the electrical system of the heart.

  • Signal-averaged EKG. This is a special EKG that averages several hundred heartbeats to detect subtle abnormalities in the movement of electrical signals through the heart.

  • Echocardiogram (ultrasound of the heart). The ultrasound shows provides assessment of the pumping and relaxing function of the heart, valve function and estimate of pressures in the heart.  It does this by using sound waves.

  • Holter monitor (extended EKG). A Holter monitor is a monitor that continually records the electrical signals of your heart for 24 hours or more.  


Additional imaging tests for cardiac sarcoidosis may include:

  • Single photon emission computed tomography (SPECT). This test can show how blood flows to tissues and organs in the body.
  • Positron emission tomography (PET)/CT Scan. A PET scan can identify active inflammation in the heart muscle suggesting active cardiac sarcoidosis. A CT scan or CAT scan is a shortened name of computerized tomography. A CT scan takes pictures of the inside of the body. The pictures are more detailed than a typical x-ray.

  • Cardiac MRI. A cardiac MRI is the best test to see evidence of any scar tissue in the heart which may lead to the cardiac complications from cardiac sarcoidosis. It also provides assessment of the size and pumping function of the heart.

A positive heart biopsy confirms cardiac sarcoidosis. However, it may more often be negative or normal even when there is sarcoidosis in the heart, especially if heart function is normal. For this reason, taking a biopsy is a less common test for detecting cardiac sarcoidosis.

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