Recent advances in the imaging assessment of infiltrative cardiomyopathies
- Department of Medicine, Flinders University, Flinders Medical Centre, Adelaide, Australia
- Correspondence to Professor Joseph B Selvanayagam, Department of Medicine, Flinders University, Flinders Medical Centre, Adelaide 5042, Australia;
Infiltrative cardiomyopathy can result from a wide spectrum of both inherited and acquired conditions with varying systemic manifestations. They usually portend an adverse prognosis, although in rare instances (eg, Fabry disease) early diagnosis can result in potentially curative treatment. Cardiac amyloid remains the archetypal infiltrative cardiomyopathy and is discussed in most detail in this article. Non-invasive imaging—principally echocardiogram and cardiovascular MRI—plays a pivotal role in the early diagnosis and follow-up of all types of infiltrative cardiomyopathy. This article focuses on the use of these modalities in infiltrative cardiomyopathy, with special emphasis on the most recent advances in imaging assessment.
Amyloidosis is a clinical disorder caused by extracellular deposition of insoluble abnormal fibrils, derived from aggregation of misfolded, normally soluble, protein.1 ,2 About 20 different unrelated proteins are known to form amyloid fibrils in vivo, which share a pathognomonic ultrastructure. Systemic amyloidosis, in which amyloid deposits are present in the viscera, blood vessel walls and connective tissues, is usually fatal and is the cause of about 1/1000 deaths in developed countries. There are also various localised forms of amyloidosis in which the deposits are confined to specific foci or to a particular organ or tissue. ‘Cardiac amyloidosis’ describes involvement of the heart by amyloid deposition, whether as part of systemic amyloidosis (as is most commonly the case) or as a localised phenomenon.
Amyloid subtype classification
Systemic AA amyloidosis, formerly known as secondary amyloidosis, rarely involves the heart (table 1). Systemic AL amyloidosis, previously known as primary amyloidosis, is the most commonly diagnosed form of clinical amyloid disease in developed countries. AL fibrils are derived from monoclonal immunoglobulin light chains and consist of the whole or part of the variable (VL) domain. The heart is affected pathologically in up to 90% of AL patients, in 50% of whom diastolic heart failure with physical …