Transthyretin Amyloid Cardiomyopathy (ATTR-CM)

What is transthyretin amyloid cardiomyopathy?

Transthyretin (trans-thy-re-tin) amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed and potentially fatal disease of the heart muscle. In ATTR-CM, a protein called transthyretin becomes misshapen and builds up in the heart, nerves and other organs. 

When these protein deposits build up in the heart, the walls can become stiff, making it hard for the left ventricle to relax and fill with blood. This is called cardiomyopathy. As the condition gets worse, the heart can struggle to pump blood, leading to heart failure. There are two types of ATTR-CM:

• Hereditary ATTR-CM (hATTR-CM)
• Wild-type ATTR-CM (wATTR-CM)

Hereditary ATTR-CM

Hereditary ATTR-CM can run in families. There’s a variant in the transthyretin gene, which results in amyloid deposits in the heart, nerves and sometimes the kidneys and other organs. Symptoms may start as early as 30, though most appear later in life.  

Hereditary ATTR-CM is more common in parts of Portugal, Brazil, Sweden and Japan. However, there are many types in different parts of the world. Some types are more common in people of Irish ancestry. Others are common among people of African descent. 

Different types may progress differently and affect various organs. The most common type in the U.S. occurs in 3%-4% of all Black people. 

Genetic testing can give helpful information for creating a treatment plan. 

Wild-type ATTR-CM

In wild-type ATTR-CM (wATTR-CM), there is no variant in the transthyretin gene, and it doesn’t run in families. It mostly affects the heart. It can also cause carpal tunnel syndrome and pain and numbness in the hands and feet, called peripheral neuropathy. Recent data suggest that problems in the lower spine and forearm tendon rupture may happen before heart symptoms. The disease most often occurs in elderly men.

What are the risk factors?

Risk factors for hereditary ATTR-CM include:

• A family member with ATTR-CM or heart failure
• Older adults
• Sex (patients are primarily male)
• Race – Black people

Risk factors for wild-type ATTR-CM include:

• Older adults
• Sex (patients are primarily male)

What are the symptoms?

Symptoms of ATTR-CM can vary or be hard to notice. The condition is often misdiagnosed. In the early stages, it looks like other heart problems, such as heart failure related to high blood pressure and enlargement and thickening of the heart, or hypertrophic cardiomyopathy. Some people may have no symptoms, while others may progress to end-stage heart failure. The symptoms of wild-type ATTR-CM are similar. They may be mild and remain undiagnosed but follow the same pattern.

ATTR-CM symptoms are like those of heart failure, including:

• Shortness of breath while resting or with little activity
• Swelling in the lower legs
• Chest congestion

Other symptoms usually occur after the shortness of breath is already there, including:

• Coughing or wheezing, especially when lying down
• Swelling in the feet, ankles and legs
• Bloating in the abdomen
• Confusion or trouble thinking
• Increased heart rate
• Palpitations or abnormal heart rhythms

Additional symptoms for ATTR-CM may include:

• Numbness or tingling in the hands and feet (hATTR-CM)
• History of spinal stenosis (wATTR-CM) 
• Carpal tunnel syndrome (wATTR-CM)

How is it ATTR-CM diagnosed?

ATTR-CM may be suspected based on common symptoms and the results from a routine cardiac test — an electrocardiogram or echocardiogram. Once suspected, more specialized tests are needed to confirm the diagnosis. These could include:

• Imaging studies of the heart, most often a cardiac MRI and/or a nuclear medicine scan of the heart
• A tissue biopsy of an affected organ
• Genetic testing 

How can ATTR-CM be treated?

There are promising new treatments available for ATTR-CM or coming soon. Talk to your health care professionals about your treatment options. 

For ATTR-CM, the focus is on easing the heart failure symptoms and slowing or stopping the amyloid deposits. Medications are approved for hereditary transthyretin amyloidosis to treat the nerve pain in the hands and feet.

In cases of advanced heart failure, heart transplantation may be an option. Since the abnormal transthyretin protein is made by the liver, some people may need both heart and liver transplants.  

Talk with your health care professionals

Awareness of ATTR-CM among health care teams is low. It’s often misdiagnosed as hypertensive heart failure. By the time symptoms appear and the person is diagnosed, it may already be advanced. 

If you have heart failure and other unresolved or seemingly unrelated symptoms, talk to your health care professional about your symptoms and treatment options. Starting that conversation could save your life. 

Tell your health care professional if you have trouble breathing. Ask them to run tests and make a treatment plan based on your diagnosis. If the tests don’t show what’s wrong, or if the treatment doesn’t improve your symptoms, ask your health care professional about next steps. Don’t give up until the tests reveal a diagnosis and the treatment helps your symptoms. 

If you have ATTR-CM, genetic testing might help your health care professional understand your condition better and choose the best treatment plan for you. 

Get support

Getting support for you and your caregivers is important for your health. Research shows that trying to handle a heart condition alone and not seeking support can make it harder to make the changes needed to live a longer, healthier life. 

You can learn more about ATTR-CM and connect with others who have this type of cardiomyopathy on the American Heart Association’s Support Network. There, you will find a community triumphing over their health obstacles each day. 

You can help others by sharing your experience and get support from people who understand what you are going through. Join for free today.