What to Know About Atrial Fibrillation in ATTR-CM

Amyloidosis can lead to a rapid, irregular heartbeat. Here’s how — plus, what you can do about it.

When you have transthyretin amyloid cardiomyopathy (ATTR-CM), proteins called amyloids build up in your heart, stiffening the muscle and interfering with its ability to pump blood throughout the body. And when your heart can’t pump blood as efficiently as it should, you can develop symptoms like shortness of breath, swelling, and disturbances to the normal rhythm of your heart, says Paul Cheng, MD, PhD, a cardiologist and a member of the Cardiovascular Research Institute at Stanford University School of Medicine.

ATTR-CM often leads to atrial fibrillation (afib), a type of arrhythmia that has been shown to affect nearly 70 percent of people with ATTR-CM.

Developing atrial fibrillation isn’t necessarily a sign that a person’s ATTR-CM is getting worse; rather, it’s a natural consequence of having the disease. “It’s almost sort of expected,” says Omar Siddiqi, MD, assistant professor of cardiovascular medicine at Boston University’s Chobanian and Avedisian School of Medicine and attending cardiologist at the Amyloidosis Center at Boston Medical Center.

Here’s everything you need to know about the link between ATTR-CM and atrial fibrillation — including what symptoms to look out for and how to minimize your risk for more serious complications, such as stroke.

Afib Is an Irregular, Rapid Heartbeat

Healthy hearts are like metronomes: They beat at a steady cadence and pump blood to the rest of the body. But when atrial fibrillation occurs, “all this becomes very chaotic,” says Prem Soman, MD, PhD, director of the Cardiac Amyloidosis Center and the Richard S. Caligiuri Endowed Chair in amyloidosis and heart failure at the University of Pittsburgh School of Medicine and UPMC. “Due to disruptions in the electrical pathways in the upper chambers of the heart, the heart starts beating irregularly and fast.”

While that sounds like it would be hard to miss, afib doesn’t always cause noticeable symptoms. You might not feel anything, you might feel some general shortness of breath or fatigue that you chalk up to any number of other causes, or you could feel noticeable heart palpitations or a quickening of your pulse, says Dr. Siddiqi.

Afib Isn’t Inherently Dangerous, but It Does Increase Your Risk for Stroke

When the heart isn’t beating rhythmically but instead enters this state of chaos, “it’s possible for blood to become stagnant in the top chambers,” says Dr. Soman. This stagnant blood predisposes people to blood clots, which can travel to the brain and cause a stroke.

In the general population, afib causes about 1 in every 7 strokes.

But if you have ATTR with afib, your risk of stroke is even higher. According to some research, 26.5 percent of people with ATTR and afib experienced a stroke, compared to 14.3 percent of people with afib who did not have ATTR-CM.

That’s why “it’s really important to identify atrial fibrillation in people with ATTR-CM,” says Dr. Soman.

ATTR-CM Sets the Stage for Afib, but Afib Can Also Occur First

Worsening amyloid deposits can trigger afib, but it doesn’t happen overnight. “Atrial fibrillation typically [develops] when somebody has had cardiac amyloidosis for a few years, but it can certainly happen earlier,” says Dr. Siddiqi.

“ATTR-CM isn’t an explosive disease,” Dr. Cheng adds. “It develops over years, and patients usually develop symptoms and get diagnosed during an acceleration phase that’s common later in the disease.”

Both ATTR and afib are more common with age, so they’re usually spotted in people in their 70s and 80s, says Siddiqi.

But sometimes a quickening heartbeat is the first sign something more serious is happening. Afib can occur when a person’s body is under stress for a different reason, such as when battling a virus or recovering from a surgery, says Cheng. They might talk to their doctor about their irregular heartbeat and only later discover through further testing that they also have ATTR, he says.

Afib Is Diagnosed by Monitoring Your Heartbeat

To see if you have afib your doctor may do diagnostic tests, such as an electrocardiogram (EKG) to look at the electrical activity of your heart or an ultrasound to see how your heart is pumping. They might also screen you using various heart rate monitors.

“In our center, for example, everybody [with ATTR] who’s diagnosed with atrial fibrillation gets a little patch that is placed on their chest. The patch continuously monitors their heart rhythm for 14 days,” Soman says. “We do this to be able to pick up atrial fibrillation that’s not obvious or that may be intermittent.”

Treatment for Afib and ATTR Can Be a Little Complicated

Afib is often treated with blood thinners to help prevent strokes, including in people who have ATTR, says Soman.

Doctors often also prescribe medications called beta-blockers for people with afib because they slow down the heart rate, but these don’t always work as well in people with ATTR-CM, says Siddiqi.

There are also procedures that are considered forms of heart rhythm control that doctors might try, says Siddiqi. These include:

Cardioversion Low-energy shocks zap the heart back into a normal rhythm, Dr. Soman says.
Ablation The damaged tissue causing the afib is destroyed by burning or freezing, which creates small scars that block the faulty signals. This treatment is recommended for people whose afib has been resistant to other types of treatment, he says.

These procedures don’t work 100 percent of the time, says Soman. Sometimes they’ll work initially, but then a person will later revert back to afib. “People typically feel better when they’re in a normal rhythm, so we try to buy them some quality of life” with these procedures and medications, says Siddiqi, “with the understanding that the afib will probably reoccur.”

The likelihood of afib recurrence, the complicated afib and ATTR treatment plans, and the nuances of amyloidosis in general are all important reasons why Soman recommends people with ATTR-CM get seen at a specialized amyloidosis center or healthcare facility. You can look for one by simply doing an internet search for amyloidosis centers near you, or you can try the treatment center selector tool from the Amyloidosis Research Consortium.

Atrial fibrillation is a common issue for people with ATTR-CM because amyloid proteins build up in the heart and interfere with its ability to pump blood. Afib might not cause noticeable symptoms, but it can raise your risk of stroke. If you have ATTR-CM, talk to your doctor about getting regular heart screenings to catch afib early.

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