Transthyretin amyloid cardiomyopathy (ATTR-CM) can cause symptoms like shortness of breath, swelling in the legs, and fatigue. Treatment can include medication or liver and heart transplants.

Transthyretin amyloidosis (ATTR) is a condition in which a protein called amyloid is deposited in your heart, nerves, and other organs. This can lead to a heart disease called transthyretin amyloid cardiomyopathy (ATTR-CM).

Transthyretin is the specific type of amyloid protein that’s deposited in your heart if you have ATTR-CM. It usually carries vitamin A and thyroid hormone throughout the body.

There are two types of transthyretin amyloidosis:

  • Wild-type ATTR: Also known as senile amyloidosis, wild-type ATTR isn’t caused by a genetic mutation. The protein deposited is in its non-mutated form.
  • Hereditary ATTR: In hereditary ATTR, the protein is formed incorrectly (misfolded). It then clumps together and is more likely to end up in your body’s tissues.

Keep reading to learn about the symptoms of ATTR-CM and how doctors treat it.

The left ventricle of the heart pumps blood through your body. ATTR-CM can affect the walls of this chamber of the heart.

The amyloid deposits make the walls stiff, so they can’t relax or squeeze normally.

This means your heart can’t effectively fill (reduced diastolic function) with blood or pump blood through your body (reduced systolic function). This is called restrictive cardiomyopathy, which is a type of heart failure.

Symptoms of this type of heart failure include:

A unique symptom that sometimes occurs is high blood pressure that slowly gets better. This happens because as your heart becomes less efficient, it can’t pump hard enough to make your blood pressure high.

Other symptoms you might have from amyloid deposits in other parts of the body besides your heart include:

When to see the doctor

If you have chest pain, call 911 immediately.

Seek medical attention right away if you develop these symptoms:

  • increasing shortness of breath
  • severe leg swelling or rapid weight gain
  • rapid or irregular heart rate
  • pauses or slow heart rate
  • dizziness
  • fainting

Each of the two types of ATTR has a unique cause.

Hereditary (familial) ATTR

In this type, transthyretin misfolds because of a genetic mutation. A child can inherit the genes responsible from a parent.

Symptoms usually start in your 50s but can begin earlier in your 20s or later in your 80s.

Wild-type ATTR

Protein misfolding commonly occurs in the body. Your body has mechanisms to remove these incorrectly formed proteins before they cause a problem.

But as you age, these mechanisms become less efficient, and misfolded proteins can clump and form deposits. That’s what happens in wild-type ATTR.

Wild-type ATTR isn’t a genetic mutation, so it can’t be passed down through the genes.

Symptoms of this type of AATR usually start after age 65.

Diagnosis can be difficult because the symptoms are the same as other types of heart failure. Tests commonly used for diagnosis include:

  • electrocardiogram to determine if the heart walls are thick from the deposits (usually, the electrical voltage is lower)
  • echocardiogram to look for thick walls, assess heart function, and look for abnormal relaxation patterns or signs of increased pressure in the heart
  • cardiac MRI to look for amyloid in the heart wall
  • heart muscle biopsy to look for amyloid deposits under a microscope
  • technetium pyrophosphate or PYP scan to look for amyloid deposits and uptake in the heart
  • genetic studies to look for hereditary ATTR

Transthyretin is mainly produced by your liver. For this reason, doctors treat hereditary ATTR-CM with a liver transplant when possible. Because the heart is often irreversibly damaged when the condition is diagnosed, they typically perform a heart transplant at the same time.

In 2019, the Food and Drug Administration (FDA) approved two medications for the treatment of ATTR-CM: tafamidis meglumine (Vyndaqel) and tafamidis (Vyndamax) capsules. Tafamidis can prevent disease progression but cannot reverse it.

Doctors may treat some of the symptoms of cardiomyopathy with diuretics to remove excess fluid.

Other medications usually used to treat heart failure, such as beta-blockers and digoxin (Lanoxin), can be harmful in this condition and shouldn’t be routinely used.

Risk factors for hereditary ATTR-CM include:

  • a family history of the condition
  • male sex
  • age over 50
  • African descent

Risk factors for wild-type ATTR-CM include:

  • age over 65
  • male sex

Without a liver and heart transplant, ATTR-CM will get worse over time. On average, people with ATTR-CM live 2.5 to 4 years after diagnosis.

The condition can have an increasingly negative effect on your quality of life, but treating your symptoms with medication can help significantly.

ATTR-CM occurs due to a genetic mutation or can be age-related. It leads to symptoms of heart failure.

Diagnosis is difficult because of its similarity to other types of heart failure. It gets progressively worse over time but can be treated with a liver and heart transplant and medication to help control symptoms.

If you experience any of the symptoms of ATTR-CM listed earlier, contact your doctor.