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Transthyretin Amyloid Cardiomyopathy (ATTR-CM)

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - What it is

Transthyretin amyloid cardiomyopathy, also known as ATTR-CM, is a type of cardiomyopathy which is underdiagnosed and potentially fatal.

In ATTR-CM, a protein called transthyretin, which circulates in the bloodstream becomes misshapen and builds up in the heart, nerves and other organs. When this protein builds up in the heart, the walls of the heart become thickened and stiff. The stiff heart is unable to relax properly to fill with blood and becomes inefficient in pumping blood to rest of the body.

As the condition progresses, the heart pumping function weakens. This results in heart failure, where the heart is unable to pump sufficient blood to meet the needs of the body.

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Symptoms

​Depending on the location and extent of the abnormal protein infiltration, initial symptoms and presentation may vary. In the early disease stage, patient may not have many symptoms. As protein accumulates in the heart muscle causing it to become stiff and thick, patients can gradually develop symptoms such as difficulty breathing (especially on walking or lying flat), leg or abdominal swelling, reduced stamina and fatigue. If the misshapen protein accumulates on the conduction system of the heart, irregular heart rhythm or excessively slow heartbeat may occur. This may cause the patient to feel giddy, faint or have palpitations. 

Deposition of protein onto the tendons may cause backaches, numbness of hand and legs. If the nerve gets affected, patient may experience tingling sensation or pain in the feet as well. Some patients develop loss of weight and bloating. Foamy urine can also occur if the abnormal protein deposits in the kidneys.

Overall, symptoms may be non-specific and common to many other disease conditions. This may have contributed to underdiagnosis of ATTR-CM.  

In summary, the symptoms for ATTR-CM may include:

  • Difficulty breathing, especially when walking or lying flat
  • Fatigue
  • Legs or abdominal swelling
  • Giddiness or fainting episodes
  • Sensation of irregular heartbeat/palpitations
  • Numbness of hands and feet
  • Pain or numbness in the lower back and legs 
  • Foamy or frothy urine
  • Unexplained loss of weight

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - How to prevent?

​In ATTR-CM, the normal protein transthyretin, which circulates in the blood, becomes deformed due to genetic mutation or ageing. While there is little one can do to reduce the risk of ATTR-CM, if you do develop the symptoms listed, it is recommended to check with your doctor on your concerns. Early diagnosis and treatment make a difference in the progression of this disease. 

If you know of any family members who have been diagnosed with the hereditary (genetic) form of Transthyretin amyloidosis, you will require a follow-up with the doctors for screening.

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Causes and Risk Factors

​ATTR-CM is caused by a deposition of abnormal misshapen proteins on the heart muscles. This protein, called transthyretin, is normally produced by the liver. Its main function is to transport the thyroid hormone and vitamin A in our bloodstream. Due to either genetic mutation or the ageing process, this transport protein can become misshapen. The abnormal proteins can then be deposited in the heart and various organs, resulting in disease.

There are two types of ATTR-CM:

1) Wild type ATTR-CM 

  • Associated with ageing
  • Mostly affecting males over 60 years old 

2) Hereditary ATTR-CM (hATTR-CM) 

  • Caused by a change or “mutation” in our gene
  • Is hereditary or passed down from birth 
  • Affects both males and females, with symptoms beginning as early as 50 years old

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Diagnosis

​Diagnosing ATTR-CM may be challenging, due to little awareness about the condition. The symptoms of ATTR-CM also overlap with those of many other common conditions.

If this condition is suspected, your doctor may need to do various tests such as an electrocardiogram (heart tracing) to assess your heart rhythm. Specialised heart imaging tests will also be ordered. This will usually include an ultrasound of the heart (transthoracic echocardiogram) to assess the heart pumping function and thickness of the heart.

Depending on the outcome of your clinical examination and test results, further dedicated heart scans such as the cardiac magnetic resonance imaging (a MRI scan of the heart) or the nuclear pyrophosphate scan (special scan to assess for possible abnormal proteins in the heart) may be performed. Blood tests will also be performed to assess various organ functions. In a small number of cases, a small sample of the affected organ, such as the heart muscle, nerve or kidney tissue, may have to be obtained to get an accurate diagnosis.

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Treatments

​The treatment for ATTR-CM is aimed towards:

  • making patients feel better or relieving symptoms 
  • reducing abnormal protein deposition on the various organs. 

Lifestyle adaptations will be advised. Medications to rid the body of excessive fluid, which may cause breathlessness and leg swelling, can be given. Certain medications that may worsen giddiness or slow down the heartbeat may be stopped by your doctor. In some cases, a special battery to regulate the heartbeat (pacemaker) may be required. If there is irregular heart rhythm, blood thinning may be prescribed to reduce the risk of a stroke.  

This is a chronic progressive condition. Although there is currently no known cure for this condition, specific treatments to reduce protein deposition on the organs have been made available. More studies are also underway. 

Should you be diagnosed with ATTR-CM, it is important to remember you are not alone. With current available treatment, most patients can still have a reasonable quality of life for several years.

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Preparing for surgery

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Post-surgery care

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) - Other Information

​Related Health Articles from National Heart Centre Singapore (NHCS)

The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth