Historically, diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM) has not been a quick and easy process. ATTR-CM is a rare, often misdiagnosed heart disease with symptoms that mimic those of other heart conditions. Sometimes patients can wait three to five years before receiving an accurate diagnosis of ATTR-CM.
The time lost could have been used to treat symptoms and slow disease progression. Fortunately, as a result of recent technological advances, ATTR-CM is becoming easier to diagnose.
What is ATTR-CM?
Transthyretin amyloidosis cardiomyopathy (ATTR-CM) is a rare progressive disease of the heart muscle that leads to congestive heart failure. It occurs when the transthyretin protein produced by the liver is unstable. Symptoms include fatigue; shortness of breath; irregular heart rate or palpitations; swelling of the legs, ankles and stomach; brain fog; wheezing; and dizziness. It often goes underdiagnosed because of a lack of awareness and knowledge of the disease. There is currently no cure for ATTR-CM.
Diagnostic tests for ATTR-CM
Earlier detection of ATTR-CM is becoming more common as there is a greater understanding of the disease, and diagnostic tools have improved. Clinicians can now use a range of invasive and noninvasive diagnostic tests to identify ATTR-CM.
Read more about ATTR-CM testing and diagnosis
Noninvasive diagnostic tests include the following.
Echocardiograms (ECG): A heart ultrasound is an initial test if ATTR-CM is suspected. It looks for abnormalities in cardiac structure and function, such as the stiffening and thickening of the wall of the left ventricle.
Electrocardiograms (EKG): This test tracks the heart’s electrical activity and monitors heart rhythm and blood flow. It detects abnormalities in the heart, damage or heart failure.
Cardiac magnetic resonance (CMR) imaging: CMR provides detailed images of the heart, giving key information on the myocardial tissue composition — in particular, the wall thickness.
Positron-emission tomography with computed tomography (PET-CT): Nuclear imaging provides a 3D image of organs and evaluates how they are functioning. A small amount of short-acting radioactive liquid is injected into the patient.
Nuclear scintigraphy: This is imaging to test for amyloid deposits in the bones. It uses tiny amounts of gamma rays found in radioactive molecules that are injected into the patient to create images of the bone, internal organs and tissue.
Immunofixation electrophoresis (IFE): This tests serum and urine to rule out a diagnosis of AL amyloidosis.
Invasive diagnostic tests may include the following.
Tenosynovial tissue biopsy during carpal tunnel release surgery: Carpal tunnel syndrome is thought to be a disease marker for ATTR-CM. It may occur years before cardiac related symptoms. During surgery, a tissue biopsy can test for amyloid deposits in the carpal tunnel tissue.
Cardiac or extracardiac biopsy: This involves a biopsy from the heart or from other tissue, such as abdominal fat or the tongue. It is not always accurate, and as an invasive test, it may carry certain risks.
Endomyocardial biopsy: Previously the cornerstone test of an ATTR-CM diagnosis, this test is reliable, but new technologies are now preferred.
Genetic testing: Once ATTR-CM has been confirmed, genetic testing will determine the subtype: wild-type (wATTR-CM) or hereditary (hATTR-CM). If molecular genetic testing detects mutations in the transthyretin gene, it indicates the presence of subtype hATTR-CM.
Improved outcomes
There is still no cure for ATTR-CM, but early diagnosis and treatment are essential to providing better outcomes for people living with ATTR-CM. This is becoming increasingly possible as a direct result of technological advances in diagnosing ATTR-CM.
Proper treatment can slow disease progression or even stop it, alleviate the burden of symptoms and improve the outlook for life expectantly.