What is ATTR-CM?
Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed condition in which misfolded transthyretin (TTR) proteins build up in the heart tissue, leading to stiffening of the heart muscle. Over time, this can cause restrictive cardiomyopathy and heart failure—and, in some cases, heart attack.
Unlike typical heart attacks caused by blocked arteries, cardiac events related to ATTR-CM often result from the heart’s inability to pump efficiently due to the thickened, stiffened walls. This difference means the warning signs of a heart attack caused by ATTR-CM may be subtler or mistaken for other conditions. Recognizing these early signs can be life-saving.
1. Shortness of Breath (Especially During Routine Activities)
One of the earliest and most common signs of cardiac distress in ATTR-CM is shortness of breath, particularly during exertion. Walking up stairs, performing household chores or light exercise may suddenly feel exhausting. In severe cases, shortness of breath may occur even at rest or while lying down (orthopnea).
This happens because the stiffened heart muscle can’t pump efficiently, leading to a backup of fluid in the lungs (pulmonary congestion). It may be mistaken for aging or being out of shape, but persistent breathlessness should be evaluated, especially in older adults.
2. Chest Discomfort or Pressure (Not Always Classic Pain)
Chest pain in ATTR-CM doesn’t always follow the classic “crushing” pain pattern seen in coronary artery disease. Instead, patients may experience chest pressure, tightness or heaviness, particularly during physical activity or stress.
The sensation may radiate to the shoulders, neck, jaw or arms. Because ATTR-CM causes gradual damage to the heart muscle, this discomfort may be dismissed as heartburn, muscle strain or anxiety—delaying appropriate care.
3. Swelling in the Legs, Ankles, or Abdomen
ATTR-CM often leads to fluid retention, which can show up as swelling (edema) in the lower extremities or abdomen. In the context of an impending heart attack, this may worsen suddenly as the heart struggles to maintain circulation.
Look for tight shoes, puffy ankles or unexplained weight gain. Abdominal bloating may also cause a sensation of fullness or loss of appetite. These signs suggest that the heart is under increasing stress and may not be pumping blood effectively.
4. Fatigue and Exercise Intolerance
Severe, unrelenting fatigue is a hallmark of ATTR-CM and a red flag that the heart is no longer functioning properly. Patients may notice that daily tasks take more effort, and even moderate exertion results in exhaustion.
This occurs because the heart can’t supply enough oxygen-rich blood to meet the body’s needs. In the lead-up to a cardiac event, this fatigue may become more pronounced and be accompanied by other symptoms like dizziness or nausea.
5. Irregular Heartbeat or Palpitations
As amyloid builds up in heart tissue, it can interfere with the heart’s electrical system. This may cause arrhythmias—irregular or rapid heartbeats—which are often described as a fluttering or pounding in the chest.
In some cases, this can lead to atrial fibrillation (AFib), a common condition in ATTR-CM patients. New or worsening palpitations, especially if accompanied by lightheadedness, fatigue or chest discomfort, can be a warning sign of impending heart failure or a cardiac event.
6. Lightheadedness or Fainting (Especially When Standing)
Amyloid deposits can impair the autonomic nervous system and blood pressure regulation. Many patients experience orthostatic hypotension, where blood pressure drops sharply upon standing. This can cause dizziness, lightheadedness or fainting.
Frequent episodes, particularly when associated with other cardiac symptoms, may indicate that the heart’s ability to maintain stable circulation is deteriorating. This can be a precursor to a serious cardiac event.
7. Unexplained Weight Loss or Muscle Wasting
While heart failure is often associated with fluid retention, ATTR-CM can also cause unexplained weight loss or muscle wasting (cachexia). This is due to the systemic effects of amyloid deposits on the gastrointestinal system and metabolism.
When seen alongside symptoms like fatigue, swelling and shortness of breath, unintentional weight loss should raise concern about underlying cardiac amyloidosis and the risk of a heart attack.
8. Nausea, Abdominal Discomfort, or Early Satiety
Some patients with ATTR-CM report digestive symptoms such as nausea, bloating and feeling full quickly (early satiety). This can be caused by congestion in the liver and gastrointestinal tract due to heart failure.
While these symptoms may not immediately point to a cardiac issue, when combined with other signs—especially in older adults—they may suggest advancing heart dysfunction that could culminate in a heart attack.
When to Seek Immediate Help
If you or a loved one with known or suspected ATTR-CM experiences multiple symptoms simultaneously—such as chest discomfort, breathlessness, swelling and fatigue—it’s critical to seek immediate medical attention. Heart attacks related to ATTR-CM may not follow the traditional pattern, but they can be just as dangerous.
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