cardiac amyloidosis
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Epidemiology
- 90% of patients with primary amyloidosis have cardiac involvement
- AL amyloidosis, transthyretin cardiac amyloidosis
Pathology
- heart is often enlarged
- thickened ventricular myocardium due to infiltration
- atria tend to enlarge
- conduction system abnormalities
- amyloid deposits in the cardiac valves
- mitral & tricuspid regurgitation common
- diastolic dysfunction: restrictive cardiomyopathy
- intractable biventricular failure
Clinical manifestations
- congestive heart failure
- arrhythmias
- sudden death
- angina
- pericardial effusion
- hepatomegaly & peripheral edema associated with right heart failure
- murmurs of mitral & tricuspid regurgitation
- manifestations of systemic amyloidosis
Laboratory
- urinalysis
- complete blood count (CBC) generally shows anemia
- serum & urine protein electrophoresis to rule out myeloma
- biopsy
- aspiration of abdominal fat pad (first line)
- myocardial biopsy (last resort)
- amyloid amyloid typing
- Val122Ile mutation in transthyretin gene is most common variant in hereditary cardiac amyloidosis*
* MGUS may co-occur with hereditary cardiac amyloidosis[2]
Diagnostic procedures
- Electrocardiography:
- Echocardiography
- increased ventricular wall thickness
- no cavity dilatation
- granular appearance of ventricular myocardium
- atria are usually dilated
- cardiac valves may be thickened
- mitral & tricuspid regurgitation is common
- prolonged ventricular relaxation in early stages with important contribution to ventricular filling from atrial contraction
- in later stages, rapid early filling suggest restrictive cardiomyopathy
Radiology
- cardiac magnetic resonance imaging[2]
- cardiac technetium-99m pyrophosphate scintigraphy diagnostic for transthyretin cardiac amyloidosis[2]
Differential diagnosis
Management
- colchicine for familial forms of cardiac amyloidosis
- treatment of light chain amyloidosis (AL amyloidosis)
- intermittent combination of prednisone & melphalan
- most successful when initiated prior to onset of heart failure & when myeloma is present
- disease recurs in cardiac transplants within 2 years
- stem cell transplantation may be an option for patients with AL amyloidosis identified before the onset of heart failure
- mean survival of untreated patients with heart failure is 6 months