Key Information
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 that normally circulates in the bloodstream becomes misshapen and builds up in the heart, nerves and other organs.
When these amyloid deposits build up in the heart, the walls can become stiff, making the left ventricle unable to properly relax and fill with blood. This is called cardiomyopathy. As the condition progresses, the heart can become unable to adequately squeeze to pump blood out of the heart, ultimately leading to heart failureexternal link, opens in a new tab. There are two types of ATTR-CM ‒ hereditary ATTR-CM (hATTR-CM) and wild-type ATTR-CM (wATTR-CM).
Hereditary ATTR-CM
In hereditary ATTR-CM, which 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, although most present later in life.
Hereditary ATTR-CM is more common in localized parts of Portugal, Brazil, Sweden and Japan; however, there are a number of variants in different parts of the world. Some variants are more common in people of Irish ancestry while others are common among people of African descent.
Different variants may progress in a different way and involve different organs. The most common variant in the United States occurs in 3-4% of all Blacks.
Genetic testingexternal link, opens in a new tab may provide important information to developing a treatment plan.
Wild-type ATTR-CM
In the wild-type ATTR-CM (wATTR-CM), there is no variant in the transthyretin gene. Wild-type ATTR-CM doesn’t run in families. It most commonly affects the heart and can also cause carpal tunnel syndrome and pain and numbness in the hands and feet, called peripheral neuropathy. Recent data suggests lumbar spine involvement and forearm tendon rupture may precede cardiac involvement. 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
- Gender (patients are primarily male)
- Race – Blacks
Risk factors for wild-type ATTR-CM include:
- Older adults
- Gender (patients are primarily male)
What are the symptoms?
Symptoms of ATTR-CM can vary or be subtle, and the condition is often misdiagnosed. In its early stages, it may mimic the symptoms of other conditions, such as heart failureexternal link, opens in a new tab related to high blood pressureexternal link, opens in a new tab, or hypertension, and enlargement and thickening of the heart, or hypertrophic cardiomyopathyexternal link, opens in a new tab. Some people may have no symptoms, while others may progress to end-stage heart failure. The symptoms of wild-type ATTR-CM are similar but may be mild and remain undiagnosed but follow the same pattern.
ATTR-CM symptoms are like those associated with heart failure including shortness of breath at rest or with minimal exertion, lower extremity swelling and chest congestion.