Transthyretin amyloid cardiomyopathy (ATTR-CM) is a potentially life-threatening condition affecting the heart muscle. It can lead to serious complications that may reduce the heart’s ability to pump enough blood to meet the body’s demands. ATTR-CM may also interfere with the heart’s electrical system that keeps it beating in a regular rhythm. The kidneys and the nervous system are also vulnerable to transthyretin amyloid cardiomyopathy complications.
With an early, accurate diagnosis and a personalized treatment plan, it may be possible to manage the condition and reduce your risk of complications. You can take steps to help reduce your risk of complications and manage problems if they happen.
What Is ATTR-CM?
It’s estimated that transthyretin amyloid cardiomyopathy (ATTR-CM) affects about 6.1 out of every 1 million adults in the U.S., though experts suggest that the condition may be underdiagnosed.
The condition involves transthyretin, a protein that helps carry vitamin A (retinol) and the thyroid hormone thyroxine throughout the body. ATTR-CM happens when abnormal forms of the protein (amyloid fibrils) build up in the wall of the heart muscle. In time, the left ventricle – the chamber that pumps blood to most of the body – grows stiffer, making it harder for the heart to supply enough blood to the body’s organs, muscle, and other tissue.
ATTR-CM can then lead to heart failure and other serious health complications.
Transthyretin Amyloid Cardiomyopathy Complications
Complications related to ATTR-CM include both cardiac and non-cardiac conditions, particularly those involving the kidneys and nervous system. Specific complications you may have depend on where amyloid fibril deposits form.
Heart failure
ATTR-CM usually leads to heart failure. Despite its name, heart failure doesn’t mean the heart fails to work. Instead, heart failure means the heart doesn’t pump as well as it should. As a result, the body stops getting a consistent and adequate supply of oxygen and nutrients.
When ATTR-CM brings on heart failure symptoms, they can include:
- Coughing or wheezing (often when you're lying down)
- Dizziness or lightheadedness
- Fatigue
- Heart palpitations
- Shortness of breath (with mild physical activity or when you're lying down)
- Trouble concentrating
Medications and a heart-healthy lifestyle may help you manage symptoms. In some cases, a pacemaker or mechanical pump may be necessary to support the heart’s pumping ability. If you have any heart failure symptoms, even if you’re not sure of the cause, see your doctor soon.
Kidney disease
When heart failure develops and healthy circulation suffers, kidney function can also be affected. With reduced blood flow, the kidneys become less effective in performing one of their main jobs, which is to filter toxins and other waste matter out of the bloodstream.
Early on with chronic kidney disease, you may not notice any symptoms. As it gets worse, you may have symptoms such as:
- Fatigue and sleep problems
- Itchy skin
- Nausea and vomiting
- Shortness of breath if fluid builds up in the lungs
- Swelling in the feet and ankles
- Urinating more or less often
Kidney disease is a serious condition that can lead to further heart problems and other complications. Multiple medications and a healthy lifestyle may be able to keep symptoms under control. But if the disease gets worse, dialysis and possibly a kidney transplant may be necessary.
Atrial fibrillation
Atrial fibrillation (AFib) is a common complication of ATTR-CM. AFib is a problem with the heart's electrical system, in which the upper chambers (atria) beat irregularly. This abnormal rhythm (arrhythmia) interferes with healthy circulation, allowing blood to pool in the heart and form dangerous blood clots. If a clot leaves the heart and travels to the brain, it could cause a stroke.
In mild cases, you may not be aware of AFib symptoms. But when they are present, AFib symptoms can include:
- A racing or irregular heartbeat
- Chest pain
- Dizziness or lightheadedness
- Fainting
- Fatigue
- Shortness of breath
Chest pain should be considered a medical emergency. Call 911 if you have it. Other AFib symptoms should be discussed with your doctor as soon as possible. It’s also worth noting that your heart can go in and out of AFib, so you may have periods when your heart is beating normally.
Carpal tunnel syndrome
Carpal tunnel syndrome happens when the median nerve – which runs down your arm to your hand – becomes compressed in the forearm. It can cause pain, tingling, and numbness in the forearm and wrist.
Carpal tunnel syndrome isn’t technically a complication of ATTR-CM. The two conditions can happen together, though, if amyloid fibrils build up in both the heart and in the carpal tunnel (the passageway that surrounds the median nerve in the arm).
Many other things – including repetitive actions such as typing – can cause carpal tunnel syndrome. But if you have lingering or frequent pain or numbness in your forearm or wrist, see your doctor for an evaluation. Wrist braces or, in serious cases, surgery can help relieve symptoms.
And while carpal tunnel syndrome unrelated to ATTR-CM may affect only one arm, when amyloid fibrils are the cause, you’re likely to have symptoms in both arms.
Peripheral neuropathy
As with carpal tunnel syndrome, peripheral neuropathy may happen alongside ATTR-CM because of amyloid fibril buildup around certain nerves, as well as the heart muscle. In the case of peripheral neuropathy, the affected nerves include those in the hands and feet that are sensitive to touch, heat, pain, etc.
Peripheral neuropathy is especially common among older adults with ATTR-CM. Research suggests that as many as 74% of older people with ATTR-CM also have peripheral neuropathy.
Symptoms of peripheral neuropathy usually include pain or tingling in the hands and/or feet. Sometimes the pain can be sudden and sharp. You may also feel muscle weakness in those areas and a loss of coordination.
Peripheral neuropathy treatment can include pain-relieving drugs, topical medications, and procedures aimed at affecting pain signals.
Spinal stenosis
One other common nerve-related condition linked to ATTR-CM is spinal stenosis, a narrowing of the area around the spinal cord. Like carpal tunnel syndrome and peripheral neuropathy, spinal stenosis is not a direct complication of ATTR-CM. Instead, it’s a condition that can be triggered by amyloid fibril buildup in the ligament flavum, one of the main ligaments that connect the vertebrae.
Spinal stenosis can cause back pain and tingling or numbness in your arms or legs. Treatment options usually range from simple things like using heat and cold on the area to physical therapy to surgery, if necessary, to ease pressure on nerves in the spine.
Outlook for Transthyretin Amyloid Cardiomyopathy (ATTR-CM)
While there is currently no cure for ATTR-CM, improvements in treatment are boosting survival rates. Getting an early diagnosis gives you the best chance for a positive outcome.
While it may be difficult to provide an exact prognosis or timeline for disease progress, your doctor may be able to give you an idea of what to expect and how you can best manage ATTR-CM and its complications.
