Cardiovascular Magnetic Resonance in Cardiac Amyloidosis

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Abstract
Myloidosis represents a diverse group of diseases characterized by the common factor of deposition of twisted -pleated sheet fibrils (amyloid) formed as a result of the misfolding of various proteins produced in several different pathological states. The different forms of amyloidosis are classified by the composition of the amyloid fibril. AL amyloidosis (previously designated as primary amyloidosis) is derived from light-chain immunoglobulin produced by monoclonal plasma cells.1 It is the most severe and probably, at least in the United States, the most common form of amyloidosis. The accumulation of amyloid disrupts the tissue architecture and, possibly in conjunction with a toxic effect from the light chains,2 leads to severe organ damage that may involve the kidneys, heart, liver, or periph- eral nerves. Familial amyloidosis is an uncommon, autosomal dominant disease with a high degree of penetrance. Most cases result from the production of an unstable variant of the serum protein transthyretin (ATTR amyloidosis). More than 80 point mutations have been identified for ATTR amyloid- osis, which predominantly results in neurological or cardiac dysfunction or both.1,3 A particularly common mutant transt- hyretin resulting from the substitution of isoleucine for valine at position 122 is found in 4% of the African American population, with an unknown penetrance. This mutation results in a cardiomyopathy that has been suggested to be one of the most common types of cardiomyopathy in older adult African American patients.4 Senile systemic amyloidosis is the result of the deposition of wild-type transthyretin and is almost exclusively limited to the heart. This disease may be becoming more prevalent because of the increasing age of the general population. Reactive systemic amyloidosis is the result of an overproduction of a nonimmunoglobulin protein AA and is rarely associated with any cardiac involvement. See p 186