Statistics from Altmetric.com
- AL amyloid
- familial amyloid
- heart failure
- cardiomyopathy restrictive
The amyloidoses are a group of diseases in which amyloid, a proteinaceous substance, deposits in one or more organs. As many as 23 different precursor proteins to the formation of amyloid have been described in man. These may deposit themselves in a fibrillar matrix within selected tissues. Fibrils are formed when normally soluble constituents undergo transformational change and misfold to become relatively insoluble. A variety of mechanisms promote these changes, which result in the final common pathway of the deposition of non-branching fibrils that can be visualised by electron microscopy and which are seen on light microscopy as a homogenous extracellular material (figure 1).
In the developed world, cardiologists predominantly encounter three main types of amyloidosis that affect the heart; light chain (AL) amyloidosis, senile systemic amyloidosis (SSA), and familial amyloidosis (FAP); the latter most commonly results from a mutation in transthyretin. In the developing world, secondary amyloid (AA) is more prevalent, due to chronic infections and inadequately treated inflammatory conditions. Occurring worldwide and later in life, a further amyloid type to affect the heart is isolated atrial amyloid (IAA).w1 w2 Finally, and much less common, are the non-transthyretin variants, including mutations of fibrinogen, apoprotein, and gelsolin. These rarer types can cause significant cardiac compromise.
Cardiac involvement in amyloidosis is usually part of a systemic disease. The heart is frequently the predominant organ affected but, in some forms of the disease, isolated heart involvement can occur. In patients with a non-cardiac biopsy showing amyloid deposition, cardiac involvement has been defined—by a consensus opinion from the 10th International Symposium on Amyloidosis1—as …