Cardiac amyloidosis
| Cardiac amyloidosis | |
|---|---|
| Human heart | |
| Specialty | Cardiology |
| Symptoms | Shortness of breath, fatigue, swelling in legs and ankles, irregular heartbeat |
| Complications | Heart failure, arrhythmias |
| Usual onset | Often insidious; may be asymptomatic for years |
| Types | AL amyloidosis, ATTR amyloidosis |
| Causes | Misfolded proteins (light chains, transthyretin) |
| Diagnostic method | Echocardiogram, cardiac MRI, biopsy, nuclear imaging |
| Treatment | Chemotherapy, stem cell transplant, heart transplant, tafamidis |
| Prognosis | Variable; depends on type and stage |
| Frequency | Rare |
Cardiac amyloidosis is a subcategory of amyloidosis where there is depositing of the protein amyloid in the heart muscle and sometimes other organs or structures. Amyloid, a misfolded and insoluble protein, can become a deposit in the heart's atria, valves, or ventricles. These deposits can cause thickening of different sections of the heart, leading to decreased cardiac function and heart failure. The overall decrease in cardiac function leads to a plethora of symptoms. This multisystem disease was often misdiagnosed, with a definitive diagnosis only during autopsy. Advancements of technologies have led to earlier and more accurate diagnosis. However diagnosis may still be delayed as the disease may remain asymptomatic for years as amyloid deposits in the heart and other organs or tissues. Diagnosis may be delayed further as the disease may be misdiagnosed or confused for other more common conditions that cause heart enlargement (such as hypertension or other forms of heart failure).
Cardiac amyloidosis has multiple sub-types including light chain, hereditary transthyretin amyloidosis (due to genetic variants leading to misfolded transthyretin protein depositing in the heart and other tissues), and wild type transthyretin amyloidosis (where misfolded transthyretin builds up in heart muscle and other tissues, but with an absence of any mutations). The genetic variants responsible for hereditary transthyretin amyloidosis are inherited in an autosomal dominant manner, with the penetrance and prevalence in a population being dependent on the specific genetic variant and other factors. Being more common in older adults, the mean age of diagnosis for both the genetic variant and wild-type variant of transthyretin cardiac amyloidosis is between age 74–90.
One of the most studied types is light chain cardiac amyloidosis. Prognosis depends on the extent of the deposits in the body and the type of amyloidosis. New treatment methods are actively being researched in regards to the treatment of heart failure and specific cardiac amyloidosis problems.