Different types of amyloidosis can affect the heart in different ways and with differing severity. The types of amyloidosis that can affect the heart include:
- AL amyloidosis
- Wild type ATTR amyloidosis
- ATTR amyloid, fibrils consist of “normal wild type” TTR in patients without mutation in the TTR gene. This condition is not hereditary.
- Hereditary amyloidosis
- ATTR amyloid, fibrils consist of “variant” TTR, in patients with mutation in the TTR gene, for example in familial amyloid polyneuropathy (FAP).
- AApoAI amyloid in patients with mutation in the apolipoprotein AI gene.
- AFib amyloid in patients with mutation in the fibrinogen gene.
- AA amyloidosis
- Heart disease is very rare in this condition, only occurring in about 2 out of every 100 patients (2%).
Symptoms of cardiac amyloidosis
Amyloid deposits in the heart muscle may cause no symptoms at all if they are small. But when amyloid deposits in the heart are large, they can lead to stiffening of the heart muscle. This is called a “restrictive cardiomyopathy”. When the heart muscle is stiff, the heart is unable to pump the blood around the body as efficiently as usual. Symptoms of heart failure may then appear.
The symptoms of heart failure caused by amyloid affecting the heart may include:
- swelling of the legs
- weight loss
- disrupted sleep
Breathlessness may be worse during exercise or when lying flat at night. Patients may feel more comfortable propped up with several pillows.
Patients with ATTR cardiac amyloidosis may also experience palpitations and disturbances in heart rhythm, such as atrial fibrillation or atrial flutter.
Amyloid hiding in the failing heart – commoner than we thought
It has been known for many years that some amyloid, usually of TTR type, is seen in many autopsies on individuals over age 80.
Up to 1 in 4 of all older people have small TTR amyloid deposits scattered around the body, including the blood vessels and the heart. Nevertheless, the finding of so-called senile cardiac amyloidosis was generally viewed as incidental. Doctors believed that cardiac TTR amyloidosis was only very rarely extensive enough to cause actual heart disease and heart failure in the elderly.
When elderly people develop heart failure, doctors often diagnose a common cause such as coronary heart disease are often diagnosed and start appropriate treatment.
But recent studies with new and improved imaging tests have led to surprising findings. It seems that amyloid hiding in the failing hearts of older people may not be as rare as previously believed. It may in fact be an under-diagnosed cause of heart failure.
As people live longer in our society and available methods of diagnosis improve, this may well become a significant public health problem. It is especially important to diagnose amyloidosis in the heart correctly since heart failure due to amyloid fails to respond to standard heart failure medications.