Cardiac amyloidosis occurs when abnormal proteins accumulate in the heart, causing the heart muscle to become thick and stiff. Over time, this buildup interferes with normal heart function and can lead to arrhythmias and heart failure.

The two main types of amyloidosis that can affect the heart are:

• Light-chain (AL) amyloidosis: This form occurs when abnormal proteins produced by the bone marrow accumulate in the heart and other organs.
• Transthyretin (ATTR) amyloidosis: In this type, the abnormal proteins originate in the liver. ATTR can occur as either hereditary (variant), caused by a gene mutation, or wild-type, which typically develops with age.

Signs & Symptoms

Cardiac amyloidosis is a progressive condition that worsens over time, often leading to heart failure and increasingly severe symptoms. Common signs include:

• Shortness of breath, even at rest or with mild activity
• Swelling in the legs, ankles, or abdomen
• Persistent fatigue lasting several days
• Heart palpitations during normal activities

Because amyloid deposits can affect other parts of the body as well, additional symptoms may occur, such as peripheral neuropathy (tingling, numbness, or pain in the hands and feet) or dysautonomia (lightheadedness, dizziness, or low blood pressure when standing).

Over time, cardiac amyloidosis alters the structure of your heart and can interfere with its electrical signaling. This can lead to several serious complications, including:

• Arrhythmias such as atrial fibrillation (AFib), bradycardia, or ventricular tachycardia
• Bundle branch block
• Cardiorenal syndrome (heart-related kidney dysfunction)
• Heart failure
• Restrictive cardiomyopathy (a stiffened heart muscle that can’t fill properly)
• Stroke

Diagnosis

Healthcare providers use a variety of tests to diagnose cardiac amyloidosis, since it is often part of a systemic, whole-body disease. This means they assess not only your heart but also look for signs of amyloid buildup in other organs.

A provider may first suspect cardiac amyloidosis based on your symptoms, medical history, and findings from a physical exam. From there, several diagnostic tests may be used to confirm or rule out the condition, including:

• Blood and urine tests to detect amyloid proteins and evaluate heart function
• Electrocardiogram (EKG) to measure the heart’s electrical activity
• Echocardiogram with strain imaging to assess heart wall thickness and stiffness
• Cardiac MRI to help distinguish amyloidosis from other types of cardiomyopathy
• Nuclear imaging scans to identify amyloid protein deposits in the heart
• Biopsy of heart tissue or another affected area to confirm amyloid presence
• Genetic testing to detect inherited forms of amyloidosis (such as hereditary ATTR)

Healthcare providers also watch for certain indicators that may suggest cardiac amyloidosis. Beyond typical heart failure symptoms, these can include:

• Atrial fibrillation (AFib)
• Thickening of the left ventricular wall
• Conduction system disease (problems with the heart’s electrical signals)
• Elevated cardiac biomarkers in blood tests
• High levels of protein in urine
• History of carpal tunnel syndrome
• Lumbar spinal stenosis
• Peripheral or autonomic neuropathy (tingling, numbness, or blood pressure changes)
• Previous shoulder surgery
• Hip or knee replacement
• These signs, especially when seen together, can prompt further evaluation for cardiac amyloidosis.