6 Sneaky Signs You Could Have ATTR-CM

When you have ATTR-CM, a protein that’s produced by your liver (called transthyretin) breaks apart and then clumps together to form what are called amyloid fibrils. Trouble is, your body can’t get rid of those clumps. Instead, they build up in various organs, wreaking havoc. “When it happens in the heart, the heart stiffens,” explains Dr. Qamar. Over time, such stiffening can cause heart failure, a condition in which your heart can no longer pump blood efficiently. Sometimes, a gene mutation causes the protein problems found in ATTR-CM, but more commonly the cause is unknown. This is called wild type ATTR-CM.

“Cardiac symptoms are rarely the first sign of the disease,” says cardiologist Dennis Finkielstein, M.D., associate chair of the Department of Cardiology at Lenox Hill Hospital in New York City. “The first signs, unfortunately, are things that are pretty common, such as carpal tunnel syndrome and low back pain.” One review found it can take more than six years for a person with wild-type ATTR-CM to get the right diagnosis after symptoms first appear. In fact, because of the variety of possible symptoms found in its early stages, it may not even be recognized as a heart problem at first.

Carpal tunnel syndrome (CTS) occurs when your median nerve, which runs through the carpal tunnel in your wrist, gets pinched. What does this have to do with ATTR-CM? Clumps of amyloid fibrils can collect in your wrists, causing your ligaments and tendons to thicken and press on your median nerve. One study reports that CPS is the most common early sign of wild type ATTR-CM, affecting up to 80% of people—and can show up five to 10 years before heart symptoms. If you have no obvious injury or arthritis, CTS may spur further testing (although the odds of it being ATTR-CM are still rare).

Lumbar spinal stenosis (LSS), a nerve-pinching narrowing of the spaces in your spine that causes pain, numbness, and tingling, is another common early symptom of ATTR-CM. Like carpal tunnel, it often begins long before heart-related symptoms. In a recent study of people who underwent LSS surgery, subsequent biopsies found that 16% of them were diagnosed with ATTRwt CA six years after surgery. "Low back pain from spinal stenosis can be one of the first signs of ATTR-CM," says Dr. Finkielstein. But like carpal tunnel syndrome, more common causes usually explain spinal stenosis, such as arthritis or back injuries.

Another nerve-related sign of ATTR-CM: peripheral neuropathy. Your peripheral nerves are nerves found outside your brain and spine. They relay messages from your brain to the rest of your body and pass signals back to your central nervous system. The most common sign that ATTR-CM has affected these nerves: pain, numbness, tingling, or burning sensations in your hands, feet, arms, and/or legs. But here’s the problem, says Dr. Finklielstein: “Neuropathy [in ATTR-CM] is easily mistaken for diabetic neuropathy.” If you already have diabetes, your doctor may not look any further for a cause of your discomfort.

Usually, a traumatic injury or overuse causes bicep tendons to rupture, or tear. People with ATTR-CM, however, appear to have a heightened risk of a spontaneous rupture, meaning that your bicep tendon could tear without cause or warning (sudden, searing pain in your upper arm or elbow may tip you off). The cause? Likely amyloid buildups in the tendon itself. In a study involving over a hundred people with heart failure, one in three people with wild-type ATTR-CM had a ruptured bicep tendon. Meanwhile, such ruptures occurred in less than 3% of those who did not have ATTR-CM.

Your doctor may not recognize ATTR-CM even when the disease causes heart symptoms, “which makes it hard to get a proper diagnosis,” says Dr. Finkielstein. In fact, ATTR-CM can lead to heart failure. As your heart becomes less and less able to pump blood efficiently, fluid builds up in your lungs and elsewhere. This leads to symptoms like shortness of breath, fatigue, and swelling, particularly in your feet and legs. This is heart failure, but because it’s caused by ATTR-CM, it requires different treatment, making an accurate diagnosis essential.

You may experience other symptoms related to your heart. “One of the initial presentations is a heart block, which causes dizziness, lightheadedness, and passing out,” says Dr. Qamar. A heart block is a heart rhythm disorder, or arrhythmia, that slows your heartbeat or causes your heart to skip beats. The result: Your heart can’t pump blood efficiently. This happens when the fibril buildups interfere with your heart’s electrical system so that its upper and lower chambers can’t communicate properly. “Sometimes this is the only symptom we’ll see, so we dig a lot further to figure out why,” says Dr. Qamar.

Until recently, identifying the cause of these symptoms made no difference, because nothing could be done to treat ATTR-CM. Fortunately, in 2019, the FDA approved Vyndamax (tafamidis), the first drug for ATTR-CM. Since then, Attruby (acoramidis) and Amvuttra (vutrisiran) have also been approved, giving doctors more tools to help slow the disease.

Now that you know some of the warning signs, be sure to tell your doctor so that the disease might be identified as soon as possible. "The earlier you diagnose, the more effective the therapy, because treatment can halt the disease's progress but can't reverse it," says Dr. Finkielstein.