How Does Cardiac Amyloidosis Affect the Heart?

Medically reviewed and verified by Kate Burke, MD, MHA

Estimated reading time: 7 minutes

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One of the many ways amyloidosis can affect the body is by accumulating in the heart. Cardiac amyloidosis is a rare but serious condition. It is characterized by the deposition of abnormal proteins, known as amyloids, in heart tissue. These amyloid deposits can disrupt the normal structure and function of the heart. Over time, this leads to a range of cardiovascular symptoms and complications.

If you feel yourself overwhelmed by the idea of the condition, or are just looking for answers, PatientsLikeMe has you covered. This overview, reviewed and edited by a team of doctors, will provide a comprehensive look at the condition. Your one stop shop for all questions cardiac amyloidosis!

What is Cardiac Amyloidosis?

When abnormal proteins build up in the heart, you get cardiac amyloidosis. Also known as "stiff heart syndrome," the amyloids replace normal heart muscle. It can occur as a primary (idiopathic) condition or secondary to other systemic amyloidosis types. In either case, the abnormal amyloid proteins accumulate in the heart tissue, particularly in the myocardium (heart muscle) and the surrounding structures.

Over time, the heart struggles more and more to pump blood. As a result, it pumps harder. Ultimately, this extra effort weakens and damages the heart, eventually causing it to fail. It is common for those with cardiac amyloidosis to have the condition in other organs.

Understanding The Heart's Structure

The heart is a complicated organ. That probably goes without saying, but while most understand that blood flows in and out of the heart, there are important parts of its structure.

• Pericardium: The heart sits inside of a double-walled sac called the pericardium. One layer is tough and fibrous, while the other is smooth and helps the heart move easily.
• Heart Wall: There are three layers to the heart wall. The epicardium is the outermost later, which covers the heart surface. The myocardium is the middle layer and is made of muscle tissue responsible for the heart's pumping action. The endocardium is the innermost layer, and the thinnest. It lines the chambers of the heart and covers the valves.
• Chambers: The heart has four chambers, two atria and two ventricles. You can think of them like rooms in a house. The atria receive blood returning to the heart. The ventricles pump blood out of the heart. Why are there two of each? The heart either sends blood to the lungs or to the rest of the body. The left side of the heart handles the body, while the right side handles the lungs.
• Valves: There are also four valves! These valves are like the doors to the rooms (the chambers). Two separate the atria from the ventricles, and the other two separate the ventricles from the arteries that carry blood away from the heart.
• Blood Vessels: The final piece is the network of blood vessels that runs throughout the body. Arteries carry oxygen-rich blood from the heart, while veins return blood back. The one exception being coronary arteries, which bring oxygenated blood to the myocardium itself.

Amyloid Proteins Effect on Heart Structure

The deposition of amyloid proteins in the heart tissue can lead to several structural changes.

1. Myocardial Stiffness: Amyloid deposits can cause the myocardium to become stiff. This impairs its ability to relax and fill with blood. This stiffness can lead to increased filling pressures in the heart chambers, contributing to heart failure symptoms.
2. Ventricular Wall Thickening: In some cases, amyloidosis can cause thickening of the ventricular walls, particularly the left ventricle. This hypertrophy can lead to impaired ventricular function and reduced cardiac output.
3. Valve Dysfunction: Amyloid deposits can also affect the heart valves, leading to valvular thickening, stiffness, and regurgitation. Valvular involvement further worsens heart failure symptoms and can contribute to complications such as atrial fibrillation.

Amyloid Proteins Effect on Heart Function

The presence of amyloid deposits in the heart tissue can impair cardiac function in several ways.

1. Diastolic Dysfunction: The stiffness of the myocardium and impaired relaxation lead to diastolic dysfunction. This is an issue with diastole, the first part of your heartbeat. Usually, the heart relaxes and fills with blood during diastole. When they do not relax as they should, the filling of the ventricles is impaired. This results in elevated filling pressures, pulmonary congestion, and symptoms of heart failure.
2. Systolic Dysfunction: In advanced stages of cardiac amyloidosis, myocardial damage can lead to systolic dysfunction. This is essentially the opposite of diastolic dysfunction. Instead of the heart struggling to fill with blood, in this case the issue is with pumping blood into the aorta. This contributes to worsening heart failure symptoms and increases the risk of cardiovascular events.
3. Arrhythmias: Arrhythmias are abnormalities in the timing or pattern of the heartbeat. It may beat too quickly or too slowly, or you may feel like your heart is skipping a beat. Damage to the heart over time because of amyloidosis increases the risk of developing arrhythmia.

Cardiac Amyloidosis Symptoms

How cardiac amyloidosis presents can vary. It depends on the extent of myocardial involvement. Common symptoms may include:

• Excessive urination at night
• Dyspnea (shortness of breath), especially with exertion
• Fatigue and weakness
• Peripheral edema (swelling in the legs and ankles)
• Orthopnea (trouble breathing while lying down)
• Heart palpitations

Diagnosis

Diagnosing cardiac amyloidosis requires a comprehensive evaluation.

1. Clinical Assessment: A thorough medical history, physical examination, and assessment of symptoms are essential. These identify the level of cardiac involvement and guide further diagnostic testing.
2. Imaging Studies: Echocardiography is the primary imaging modality used to evaluate cardiac structure and function in patients suspected of having cardiac amyloidosis.
3. Biomarkers: Serum biomarkers such as NT-proBNP (N-terminal pro-B-type natriuretic peptide) and troponin may be elevated in patients with cardiac amyloidosis. They can provide additional diagnostic information.
4. Cardiac MRI: Cardiac magnetic resonance imaging (MRI) can help assess myocardial tissue characteristics. These include the presence and distribution of amyloid deposits.
5. Endomyocardial Biopsy: Although invasive, endomyocardial biopsy remains the gold standard for confirming the presence of amyloid deposits in the heart tissue and determining the specific amyloid subtype.

Treatment and Management

The management of cardiac amyloidosis aims to alleviate symptoms, improve quality of life, and slow disease progression. Treatment approaches may include:

1. Supportive Care: There are several ways to treat the disease's symptoms. Diuretics help to alleviate fluid retention, and beta-blockers or calcium channel blockers control atrial fibrillation. Anticoagulation therapy can reduce the risk of blood clots.
2. Disease-Modifying Therapy: There are a few emerging treatments targeting the underlying amyloidosis process. These include novel agents such as monoclonal antibodies, small interfering RNA (siRNA) inhibitors, and small molecule inhibitors of amyloid fibril formation. These therapies aim to reduce amyloid deposition, prevent further myocardial damage, and improve cardiac function.
3. Heart Transplant: In select cases of advanced cardiac amyloidosis, heart transplantation may be considered. However, the presence of systemic amyloidosis and associated multi-organ involvement may limit candidacy for transplantation in some patients.

Understanding the effects of amyloidosis on the heart is essential! With understanding comes timely diagnosis, appropriate management, and optimization of patient care. It requires a multidisciplinary approach to manage this condition. Through targeted therapies, healthcare providers can strive to improve outcomes and enhance the quality of life for patients affected by this rare but impactful disease.

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