Transthyretin amyloid cardiomyopathy is a heart condition caused by the buildup of abnormal proteins in the heart muscle. It’s a life-threatening disease that can cause serious complications.
And while there’s currently no cure, there are treatments that can help slow the buildup of transthyretin proteins and manage your symptoms.
What Is Transthyretin Amyloid Cardiomyopathy?
Transthyretin (TTR) is a protein that helps move vitamin A (retinol) and the thyroid hormone thyroxine through the bloodstream and throughout the body.
Transthyretin amyloid cardiomyopathy, better known as ATTR-CM, happens when misfolded transthyretin proteins form amyloid fibrils within the wall of the left ventricle – the heart’s main pumping chamber. As a result, the ventricle gets stiff and becomes too weak to pump enough oxygen-rich blood to meet the body’s demands. A weakened heart muscle is known as cardiomyopathy, and it can be the first step toward heart failure.
Transthyretin Amyloid Cardiomyopathy Treatments
ATTR-CM treatment has two primary goals: slowing or preventing the formation of amyloid deposits in the heart, and managing heart failure symptoms and other complications of the disease.
The following medications are aimed at affecting the buildup of abnormal TTR.
Tafamidis
The oral medication tafamidis (Vyndamax, Vyndaqel) was the first drug approved by the FDA for the treatment of ATTR-CM. It works by stabilizing the TTR and keeping it from misfolding into amyloids that build up in the heart wall. In this way, the drug slows the progression of the disease.
Tafamidis is a promising treatment option. But like all powerful medications, it can cause side effects. Among them are:
- Gastrointestinal troubles, including gas, diarrhea, and abdominal (belly) pain
- Headache
- Peripheral edema (swelling, mostly in the feet and ankles)
- Pneumonia or flu
- Urinary tract infection
It’s important to inform your doctor of these or any other side effects that may be related to tafamidis. To help monitor your health while you take the medication, you also may be advised to get periodic tests, including:
- Complete blood count (CBC)
- Electrocardiogram
- Kidney function
- Liver function
- Thyroid function
Acoramidis
Acoramidis (Attruby) is the only other FDA-approved drug for the treatment of ATTR-CM. Like tafamidis, acoramidis is a TTR protein stabilizer. Research suggests acoramidis may work better, in some ways, than tafamidis in stabilizing TTR protein.
Acoramidis may be a safe and effective alternative to tafamidis. Still, some side effects are common, including upper abdominal pain and diarrhea. Any symptoms that you think may be related to acoramidis should be reported to your doctor promptly.
Vutrisiran
Vutrisiran (Amvuttra) helps treat ATTR-CM by interfering with the production of TTR proteins in the liver.
Vutrisiran is injected under the skin every three months. You may need to take a vitamin A supplement, because a reduction in TTR proteins in the bloodstream may mean less vitamin A is circulating throughout the body, too.
You may get some side effects when you’re taking vutrisiran. If you do, call your doctor’s office as soon as you can, or call 911 if you have issues such as chest pain or trouble breathing. Some of the more common side effects are:
- A hard time breathing
- Chest tightness
- Muscle pain
- Vision problems
Inotersen
Inotersen (Tegsedi) is another drug that reduces TTR protein production in the liver. The injectable medication is meant for people who have a condition called hereditary transthyretin-mediated amyloidosis (hATTR), in which a mutated form of the TTR gene causes misfolding of the TTR proteins.
The list of potential side effects with inotersen is long. Not all of them require medical attention, but you should report any side effects to your health care provider for guidance. Among inotersen side effects are:
- Black, tarry stools
- Bleeding gums
- Blood in your urine or stools
- Chest tightness
- Cough
- Dizziness, lightheadedness, or fainting
- Fever
- Headache
- Joint pain
- Nausea and vomiting
- Shortness of breath
- Swelling in the hands, feet, or face
- You don’t pee as often
Patisiran
Like inotersen, patisiran decreases the liver’s production of abnormal TTR proteins. It’s also prescribed to people diagnosed with hATTR.
The injectable drug carries some side effect risks. As with any medication, serious side effects should be reported to the doctor who prescribed it. Among them are:
- Aches and pains, particularly in the back
- Chest tightness
- Cough and a hard time breathing
- Ear and nasal congestion
- Nausea and vomiting
- Sore throat
Treatments for ATTR-CM Complications
Because ATTR-CM can lead to heart failure and other complications, including atrial fibrillation and kidney disease, your treatment may require medications or procedures to address multiple conditions.
Heart failure
Effective heart failure treatment usually involves a combination of medications and adopting a lifestyle that involves regular exercise and a heart-healthy, low-sodium diet.
Heart failure is a chronic condition, so you will need to manage it for the rest of your life.
Atrial fibrillation
Atrial fibrillation (AFib) happens when the beats in the heart’s upper chambers (atria) are not regular, making the heart less effective in pumping blood out to the body. A heart in AFib also can allow blood to pool in the heart, forming a dangerous blood clot. If the clot travels to the brain, it could cause a stroke.
The right treatment for it depends on how serious and often the AFib episodes are and whether you have other heart conditions. You may need a blood thinner to help prevent blood clots, as well as other medications to manage your heart rate and blood pressure. In some cases, a procedure such as ablation may be needed to help restore a healthy rhythm. In an ablation, heat or cold are used to cause scarring in an area of the heart. That scar tissue blocks the electrical signals that cause irregular heartbeats. That can help bring back a normal heart rhythm.
Kidney disease
When the heart isn’t able to supply a steady, robust supply of blood to the kidneys, their function can suffer. In addition to a healthy lifestyle, you may be prescribed medications to help lower blood pressure and cholesterol, reduce fluid buildup in the legs and elsewhere, and protect your bones.
Transplant, when other treatments stop working
When standard treatments are no longer effective in keeping certain organs functioning well enough to keep the body healthy, your doctor may recommend that you consider an organ transplant.
A heart transplant is sometimes necessary for end-stage heart failure. Seriously reduced liver or kidney function may require a liver or kidney transplant.
Outlook for ATTR-CM
With improvements in medications, the prognosis for someone with ATTR-CM is looking better. Working closely with your cardiologist and other specialists will give you the best chance of extending your life and managing ATTR-CM symptoms and complications.
