What is cardiac amyloidosis?
- Cardiac amyloidosis is recognised as one of the leading causes of heart failure with preserved ejection fraction (HeFPEF).
- Most amyloid proteins are naturally occurring proteins in the body. For example, the transthyretin protein is responsible for transporting thyroid hormones.
- Amyloid can deposit in many different parts of the human body including the heart, kidney, nerves, gastrointestinal tract and liver.
If amyloid deposits build up in the heart it can cause the left ventricle (the main pumping chamber of the heart) to become thicker and stiff, this causes the heart to become weaker and less able to supply the body with blood (known as heart failure).
Cardiac amyloidosis is the term used when amyloid protein deposits are found in the heart and they cause damage to heart function. The vast majority of cardiac amyloidosis are one of three types:
- AL (light chain)
- hATTR-CM (hereditary TTR amyloidosis, also called familial TTR amyloidosis)
- wATTR (wild-type TTR)
hATTR-CM is a genetic condition caused by a genetic variant in the transthyretin gene, making it more unstable and more likely to fold up on itself and form amyloid deposits normally affecting the heart and nerves, both the peripheral (hands and feet) and the main autonomic nerves.
wATTR-CM is a condition of older age, where normal transthyretin protein becomes unstable and is deposited in the heart more gradually. It was previously called 'senile systemic amyloidosis'.
Symptoms
Amyloid protein deposits in the heart can in some people lead to:
- Heart failure - symptoms can include: shortness of breath during activity or while at rest, fatigue, fluid build-up in the abdomen, legs and ankles and for some people difficulty lying flat at night.
- Heart rhythm abnormalities (arrhythmias) - which most commonly include atrial fibrillation. Symptoms can include light-headedness, dizziness, palpitations, shortness of breath, and fatigue.
- Valvular disease - if amyloid deposits occur in the valves of the heart, this can lead to leaky or narrowed valves. Occasionally, people being treated for severe aortic stenosis are found to have cardiac amyloidosis. Symptoms can include shortness of breath, reduced ability to exercise, feeling lightheaded and dizzy.
Treatment
Treatment of cardiac amyloidosis aims to reduce the symptoms, including heart failure symptoms and potential complications of amyloidosis while other treatments treat the underlying condition.
Treatments can include medications to help control the fluid level in the body with dietary modifications, diuretics including Mineral Receptor Antagonists (MRA’s) and SGLT2 inhibitors. In some cases, patients require beta blockers to control concurrent atrial fibrillation (AF), device implantation, and, in some cases, heart and/or liver transplantation.
Medications which treat the condition and stabilise the amyloid deposits, for example, Tafamidis, have been shown to help slow the progression of the condition, help reduce symptoms, increase exercise ability and reduce hospitalisation of people diagnosed with wATTR-CM when started soon after diagnosis. Tafamidis is approved by the The Scottish Medicines Consortium (SMC) for treating transthyretin amyloidosis with cardiomyopathy. It is a once-daily medication which can slow the rate of disease progression and may reduce heart failure symptoms.
With thanks to Dr Tamer Rezk, Royal Free London NHS Trust Foundation, for his input on this page