The "Stiff Heart" Condition: Understanding Cardiac Amyloidosis (ATTR-CM)

Most people think heart disease shows up the same way every time—chest pain, shortness of breath, maybe a trip to the emergency room. 

But some heart conditions are far quieter. 

They creep in slowly. The symptoms are subtle at first—fatigue, swelling in the legs, and feeling short of breath when walking across the room. It can look like normal aging or common heart failure. But in some cases, the real cause is something many people have never heard of: cardiac amyloidosis, also known as ATTR-CM. 

"Cardiac amyloidosis is often underrecognized because the symptoms overlap with other common heart conditions," explains Archbold cardiologist Dr. Kashyap Choksi. "The key is understanding what's happening inside the heart and recognizing the warning signs early."

Let's break down what cardiac amyloidosis actually is—and why cardiologists are paying closer attention to it today. 

What Is Cardiac Amyloidosis (ATTR-CM), the "Stiff Heart" Disease? 

To understand cardiac amyloidosis, it helps to picture the heart like a sponge. 

A healthy heart muscle is flexible. It squeezes and relaxes easily with every beat, pumping blood throughout the body. 

With cardiac amyloidosis, abnormal proteins called amyloid begin to build up inside the heart muscle. Over time, these deposits make the heart walls stiffer and thicker, which prevents the heart from filling with blood and pumping normally. 

Why ATTR-CM Can Be Difficult to Recognize

One of the challenges with cardiac amyloidosis (ATTR-CM) is that it doesn't always look like typical heart disease. 

In many patients with this disease, the heart appears thicker than normal on imaging tests, which can sometimes be mistaken for other conditions such as hypertensive heart disease or hypertrophic cardiomyopathy. But in ATTR-CM, the thickening isn't caused by stronger muscle—it's caused by amyloid protein deposits building up inside the heart tissue. 

"The heart walls may appear thick on an echocardiogram, but the problem isn't excess muscle," explains Dr. Kashyap Choksi, cardiologist at Archbold. "It's actually the accumulation of abnormal protein within the heart muscle itself."

Over time, these protein deposits interfere with the heart's ability to relax and fill properly between beats. As the condition progresses, this can lead to symptoms that resemble heart failure—even though the underlying cause is very different. 

This is one reason cardiologists are placing greater emphasis on early detection and specialized testing when symptoms don't quite fit the typical pattern. 

Common Symptoms of Cardiac Amyloidosis

Because the heart becomes less efficient over time, symptoms often develop gradually and may be mistaken for other conditions.

Common signs of ATTR-CM may include: 

• Shortness of breath, especially with activity
• Fatigue or reduced energy levels
• Swelling in the legs, ankles, or feet
• Irregular heart rhythms
• Dizziness or lightheadedness
• Difficulty exercising or climbing stairs

Some patients also experience symptoms outside the heart, such as carpal tunnel syndrome, numbness in the hands, or spinal issues, sometimes years before heart symptoms appear. 

"Many patients are surprised to learn that symptoms like carpal tunnel syndrome or unexplained fatigue can be connected to cardiac amyloidosis," says Dr. Choksi. "These clues can help physicians identify the condition earlier." 

Who Is Most as Risk for ATTR-CM?

Cardiac amyloidosis can affect people in different ways, but certain groups are more likely to develop the condition. 

Risk factors may include: 

• Age, particularly adults over 60
• Male gender
• Family history of amyloidosis
• Certain genetic variants
• A history of heart failure with preserved ejection fraction (HFpEF)

It's also important to note that there are two primary forms of ATTR-CM, and understanding the difference can help guide both diagnosis and treatment. 

Wild-type ATTR

Wild-type ATTR develops gradually with age and is not inherited. It most commonly affects adults over 60 and is more common in men. Because its symptoms can resemble common forms of heart failure, it has historically been underdiagnosed. Many patients may have symptoms for years before the condition is recognized. 

Hereditary ATTR

Hereditary ATTR is caused by a genetic mutation passed down through families. The mutation affects the transthyretin protein, making it more likely to form amyloid deposits in the heart and sometimes in other parts of the body, such as the nerves. People who inherit the mutation may develop symptoms earlier in life, although the age of onset can vary. Three to four percent of African Americans have the mutation in the TTR gene, that leads to hereditary ATTR-CM.

“Because one form of ATTR-CM can be inherited, identifying the condition can sometimes help protect other family members as well,” Dr. Choksi explains. “If we diagnose hereditary ATTR, it may allow relatives to be screened and monitored so we can detect potential heart issues earlier. Hereditary forms of ATTR tend to have early onset symptoms compared to Wild-type ATTR.”

In many cases, genetic counseling or testing may be recommended to help families better understand their risk and take proactive steps toward protecting their heart health. 

Why Early Diagnosis Matters

For many years, cardiac amyloidosis was difficult to diagnose and often discovered late. 

Today, new imaging techniques, blood tests, and nuclear scans have made it much easier for cardiologists to detect the disease earlier. 

And that's important—because treatment options have improved significantly. 

"When we identify cardiac amyloidosis earlier, we have more opportunities to slow the progression of the disease and help patients maintain their quality of life," says Dr. Choksi. "New medications can help stabilize the transthyretin protein and reduce further amyloid buildup."

When to Talk to Your Doctor

It you've been diagnosed with heart failure but continue to experience unexplained symptoms, it may be worth asking your doctor whether further evaluation is needed. 

You should also speak with your physician if you experience: 

• Ongoing shortness of breath
• Unusual fatigue
• Persistent swelling in the legs
• Heart rhythm issues
• A family history of amyloidosis

"Cardiac amyloidosis is still considered a relatively rare condition, but we're recognizing it more often as awareness improves," Dr. Choksi explains. "If something doesn't seem right with your heart health, it's always worth having a conversation with your primary care doctor or cardiologist."

Expert Heart Care Close to Home

At Archbold, patients have access to experienced cardiologists and advanced diagnostic tools to evaluate complex heart conditions, including cardiac amyloidosis. 

If you have concerns about your heart health or are experiencing symptoms of heart disease, the cardiology team at Archbold is here to help. 

To schedule an appointment with an Archbold cardiologist, speak with your primary care provider about a referral.