What is cardiac amyloidosis?
Cardiac amyloidosis is a condition that occurs when an abnormal protein-like substance known as amyloid builds up in the heart. There are different proteins that can cause cardiac amyloidosis, and the treatment approach varies depending on the specific type of protein involved.
What are cardiac amyloidosis symptoms?
Cardiac amyloidosis may cause symptoms such as shortness of breath, leg or abdominal swelling, and atrial fibrillation, leading to palpitations or a rapid, irregular heartbeat. These symptoms, along with others, could indicate amyloidosis involvement beyond the heart. Additional signs may include:
- A history of carpal tunnel syndrome, spinal stenosis, trigger finger, or a torn biceps tendon
- Unexplained bruising around the eyes
- Numbness and tingling in the legs (neuropathy)
- Enlargement of the tongue
- Foamy urine
What are the main types of cardiac amyloidosis?
There are two main types of amyloidosis that lead to amyloid heart disease, each defined by the specific protein responsible for forming the amyloid.
ATTR amyloidosis
ATTR amyloidosis is the most common type of cardiac amyloidosis, characterized by the buildup of a protein called transthyretin (TTR) in the heart. This can result from an excess of normal TTR or, less commonly, a mutated form of it. Normal TTR amyloid heart disease typically occurs in men aged mid-60’s and older. Amyloidosis caused by a mutant protein is hereditary, most common in patients of African descent, and leads to congestive heart failure after the age of 60, affecting both men and women.
AL amyloidosis
AL amyloidosis, short for "light-chain amyloidosis," is a condition where abnormal cells in the bone marrow produce amyloid protein. While less common than TTR amyloidosis, AL amyloidosis can affect multiple organs besides the heart, such as the kidneys, liver, skin, bowel, and nerves. It can be linked to multiple myeloma, a type of blood cancer that affects plasma cells in the bone marrow. AL amyloidosis develops rapidly, but chemotherapy can effectively halt its progression.
What are the risk factors of cardiac amyloidosis?
Cardiac amyloidosis is relatively uncommon and typically not preventable, as its risk factors are often beyond our control. The commonly accepted risk factors include:
- Age: Individuals over 40 are more likely to develop AL cardiac amyloidosis, with most diagnoses occurring in patients aged 50 or older. TTR cardiac amyloidosis tends to occur after the age of 60.
- Race: Due to the inheritable nature of certain types of amyloidosis, it may be more common in specific genetic demographics. For example, individuals of African descent are at a greater risk of developing inherited amyloidosis.
- Sex: TTR amyloidosis is more common in males, whereas AL amyloidosis affects both men and women equally.
How is cardiac amyloidosis diagnosed?
Cardiac amyloidosis is typically diagnosed through a series of diagnostic tests:
- Cardiac ultrasound (echocardiogram): This is often the first step when cardiac amyloidosis is suspected. It can reveal abnormalities that are linked to amyloidosis and not commonly seen in other heart conditions.
- Heart MRI: This imaging test can provide more specific information about the presence of cardiac amyloidosis.
- Technetium pyrophosphate scan: This scan is a specialized imaging test that helps doctors diagnose and classify cardiac amyloidosis.
- Blood tests: Blood tests can detect abnormal proteins associated with AL amyloidosis. However, a definitive diagnosis usually requires a biopsy of tissue that shows amyloid deposits.
These diagnostic procedures help confirm the presence of cardiac amyloidosis and distinguish between its different types.
How is cardiac amyloidosis treated?
Cardiac amyloidosis treatment varies based on the type of amyloid protein involved.
- How to treat TTR amyloidosis: Effective medications can slow or stop the deposition of amyloid in the heart, slowing the progression of the disease. However, existing amyloid deposits are not significantly affected by these drugs.
- How to treat AL amyloidosis: Treatment typically involves chemotherapy or similar drugs that stop the production of new amyloid. Once abnormal protein production is stopped, patients may experience an improvement in their symptoms, even though existing amyloid deposits remains in the organs.
Can cardiac amyloidosis be prevented?
Cardiac amyloidosis is generally not preventable. However, for patients with familial amyloidosis, proactive screening of family members can help identify those with the abnormal gene. There are then therapeutic interventions that may potentially prevent the onset of the disease.
Living with cardiac amyloidosis
Progress in the diagnosis and treatment of cardiac amyloidosis has been significant over the past decade. Early diagnosis is has enabled successful treatment, allowing patients to lead active lives. Ongoing clinical trials for novel therapies also offer hope for removing amyloid from the heart and other affected organs. The prognosis can be very good when patients are diagnosed early and receive treatment from a specialist in cardiac amyloidosis who can accurately identify the type of amyloid and develop a personalized treatment plan.
