Professor James Moon, Professor of Cardiology at University College London and Director of Imaging at Barts Heart Centre, explains amyloidosis - a condition which comes in many different forms.
What is amyloidosis?
Amyloidosis is caused by an accumulation of abnormal protein, called amyloid deposits. If these build up in your body they can cause. The heart and the kidneys are some of the organs which are most often affected. In severe cases it can lead to failure of the organ and death.
What are the different types of amyloidosis?
There are many types of amyloidosis. Two types in particular affect heart muscle:
ATTR, which can be due to an inherited gene mutation (hereditary ATTR) or not (wild-type ATTR). It is this second type which seems to be common in the elderly and particularly likely to affect the heart. It causes stiffening and thickening of the heart, which in turn can result in symptoms of heart failure, such as breathlessness.
The other type, AL (primary light chain) amyloidosis, has in the past been thought to be the most common type, although this is now being questioned by our research. It is caused by the deposition of light chain fragments from abnormal plasma cells. Normally these are a healthy part of your immune system, but instead they go wrong and build up in your organs. It’s a bit like cancer, in which abnormal cells divide in an uncontrolled way, and like cancer, it requires treatment with chemotherapy. This type can occur at any age, and often affects younger patients.
How is it diagnosed?
The initial symptoms can vary, depending on where the amyloid has built up and include anything from numbness, pain or tingling in the wrists (carpal tunnel syndrome) or hands and feet, to diarrhoea or constipation, to symptoms of heart failure such as breathlessness and swollen ankles. But these symptoms can be caused by other things too, so careful investigation is needed to make the diagnosis – including the use of a bone scan, which has been shown to be highly sensitive in detecting ATTR cardiac amyloidosis.
The earlier the disease is diagnosed often the better the outlook – it’s important to get early treatment, especially for AL amyloidosis. But it can sometimes be difficult to diagnose at the early stages, because the symptoms vary so much.
How is it treated?
There are treatments available, but much better treatments are being developed, with the support of the British Heart Foundation.
For ATTR cardiac amyloidosis, currently the focus of treatment is the management of symptoms, but there are some existing treatments, and more in development, that can reduce the process that leads to the amyloid deposition. Some of the new treatments are using RNA (part of your genetic material) to “silence” or de-activate the relevant genes – this disrupts the production of amyloid. At the National Amyloidosis Centre, with BHF support they are developing new treatments using monoclonal antibodies – a type of immunotherapy – that can mop up the amyloid that is already there. They can really drop the levels of amyloid and are very exciting. If you can remove the amyloid, the organ function can be restored much more rapidly. We are within a few years of new treatments.
The treatment of AL cardiac amyloidosis involves the use of chemotherapy, sometimes combined with stem cell transplantation to treat the underlying abnormal plasma cells.