About Giant Cell Myocarditis

Discover Giant Cell Myocarditis Causes, Symptoms, Diagnosis and Treatment (GCM)

About Giant Cell Myocarditis

If you ask the average person to define giant cell myocarditis, there’s a good chance they’ll be unable to. The same goes for a majority of physicians. While the more common viral myocarditis is considered a rare disease, giant cell myocarditis is even less common, affecting only a small fraction of individuals each year. And while this condition may be uncommon, it can have serious consequences.

The first case of giant cell myocarditis was described by medical professionals in 1905. However, our understanding of the disease is still developing. From 1905 until 1987, all cases of Giant Cell Myocarditis were described at autopsy, with survival usually less than 3 months from the initial onset of symptoms.

How is Giant Cell Myocarditis Diagnosed?

Giant cell myocarditis can only be confirmed and diagnosed through a heart biopsy. During this procedure, a catheter is inserted into one of the larger blood vessels in the neck or groin. An instrument called a bioptome is then placed inside the catheter and used to remove a small piece of tissue. This is a dangerous procedure especially in someone who already would be so very compensated cardiac-wise. It is essential that your results are reviewed by an experienced cardiac pathologist to confirm the diagnosis.

Can the Biopsy Results be Confused with a Different Disorder?

Giant cell myocarditis can be confused with cardiac sarcoidosis. Therefore all suspected cases should be reviewed by an experienced cardiac pathologist.

How is an Endomyocardial Biopsy Performed?

A thin tube called a catheter is inserted into a vein or artery, usually in the groin or neck. The catheter is guided using x-ray or echocardiogram (sonogram for the heart) and placed inside of the heart. Then an instrument called a bioptome is inserted into the catheter and used to remove a small section of the heart from the inside.

How is Giant Cell Myocarditis Treated?

Once diagnosed, your physician will prescribe immunosuppressive drugs and corticosteroids. These medications help reduce inflammation and help to prevent complications, including heart failure and arrhythmias. While many patients may eventually require a transplant, medications can delay the need for the procedure for months or even years.

What are Some of the Treatments for Giant Cell Myocarditis?

The goal of immunosuppression therapy is to delay heart transplantation. The need for a transplant may is delayed by months or even years. Since each case is unique there is no typical time.


The cause of giant cell myocarditis is not known, but observations in human tissue and experimental data from a Lewis Rat model suggest that the disease is mediated by T lymphocytes.

Experimental giant cell myocarditis can be produced in the Lewis rat by auto immunization with myosin.

No. Giant cell myocarditis was first described in 1905.

Giant cell myocarditis is a very rare disease. Therefore many physicians are not familiar with giant cell myocarditis.

Post-transplantation survival is approximately 71% at five years despite a 25% rate of giant cell infiltration in the donor heart. To confirm these findings, a randomized trial of immunosuppression drugs and steroids is underway.

Fast treatment can yield positive results and reduces the rate of death or need for heart transplantation.

In many cases, a transplant will eradicate the presence of giant cell myocarditis. However, a percentage of those who receive a transplant will experience growth of giant cells in their new heart.

Additional research is being completed to determine the risk of giant cell growth in the hearts of transplant recipients. While more study is required, scientists believe that the growth of these cells may be less severe due to the immunosuppressants patients take to help their bodies accept donor hearts. And because regular biopsies are performed to guard against transplant rejection, constant monitoring helps identify excessive cell growth as it occurs.

The exact reason is not known. But the disease may be less aggressive because the patients are on immunosuppressive drugs to prevent rejection of the donor heart.

The treatment depends to some degree on the presentation, but may consist of steroids for 2-3 months.

The diagnosis is made by heart biopsy, which is routinely performed in the post-transplant patient to look for rejection of the donor heart.

The range of time to recurrence is wide, from 3 weeks to 9 years after transplant, with an average time of about one year.

The Search for a Cure Continues

Today’s patients and healthcare providers have more information than ever about giant cell myocarditis. Still, there are many discoveries yet to be made, and the Myocarditis Foundation is dedicated to supporting researchers and physicians in the search for a cure. If you or a loved one has been diagnosed with giant cell myocarditis, our extensive research library and frequently asked questions can help provide some of the answers you seek. To learn more, contact us today or make a donation to contribute to our mission.

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