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If you have been diagnosed with transthyretin amyloid cardiomyopathy (ATTR-CM), your care team has likely talked with you about how your heart muscle is working. In particular, you may have discussed how well your heart pumps blood and whether the muscle has become thicker or stiffer over time.
With ATTR-CM, amyloid deposits gradually build up in the heart. These deposits are made of a protein called transthyretin (TTR). Over time, amyloid deposits can cause the heart muscle to become thicker and less flexible than it should be. This is where the cardiomyopathy in ATTR-CM comes from. Cardiomyopathy simply means disease of the heart muscle. ATTR-CM also is a form of amyloidosis, a group of conditions caused by misfolded protein deposits in the body’s tissues. When amyloidosis affects the heart, it is often referred to as cardiac amyloidosis.
ATTR-CM is a complex condition, but the key takeaway is this: ATTR-CM affects the heart muscle and how the heart fills with and pumps blood.
Below, Omar F. Abou Ezzeddine, M.D., M.S., a cardiologist and cardiomyopathy expert at Mayo Clinic in Rochester, Minnesota, explains what cardiomyopathy means in ATTR-CM, including why it happens, what symptoms to watch for and lifestyle tips that may help you manage the condition.
What causes cardiomyopathy?
Cardiomyopathy is a disease of the heart muscle. While there are many different types and causes, cardiomyopathy ultimately makes it harder for the heart to work — filling with blood, pumping blood or both.
A healthy heart muscle is flexible, allowing it to relax and fill with blood between beats, then contract to pump out blood. With ATTR-CM, amyloid deposits collect between healthy heart cells. Over time, this buildup causes the heart muscle to become thicker and stiffer. As a result, the heart has a harder time relaxing enough to fill up with blood and, in some situations, squeezing effectively to pump out blood.
As the heart becomes stiffer, pressure inside the heart rises, explains Dr. Abou Ezzeddine. “Imagine trying to blow air into a very stiff balloon,” he says. “You have to blow much harder to fill it. The same thing happens in the heart. It takes more pressure and effort to fill it with blood.”
Over time, some people with ATTR-CM may develop heart failure. This means the heart can no longer keep up with the body’s demands. To learn more about heart failure related to ATTR-CM — and how to talk with friends and family about it — see Mayo Clinic’s guide.
In addition to heart failure symptoms, ATTR-CM also can affect the heart’s conduction system, which controls heart rhythm. The conduction system uses electrical signals in the heart to regulate the heartbeat. When electrical signaling is disrupted, the heart may beat too fast, too slow or irregularly. This is called an arrhythmia. Atrial fibrillation, a rapid and irregular heartbeat, is the most common arrhythmia in people with ATTR-CM. Finally, Dr. Abou Ezzeddine says conduction issues also can increase the risk of heart block, which may require treatment such as a pacemaker.