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cardiac amyloidosis
Epidemiology:
- 90% of patients with primary amyloidosis have cardiac involvement
- AL amyloidosis, transthyretin cardiac amyloidosis
Pathology:
1) heart is often enlarged
2) thickened ventricular myocardium due to infiltration
3) atria tend to enlarge
4) conduction system abnormalities
5) amyloid deposits in the cardiac valves
6) mitral & tricuspid regurgitation common
7) diastolic dysfunction: restrictive cardiomyopathy
8) intractable biventricular failure
Clinical manifestations:
1) congestive heart failure
2) arrhythmias
3) sudden death
4) angina
5) pericardial effusion
6) hepatomegaly & peripheral edema associated with right heart failure
7) murmurs of mitral & tricuspid regurgitation
8) manifestations of systemic amyloidosis
Laboratory:
1) urinalysis
2) complete blood count (CBC) generally shows anemia
3) serum & urine protein electrophoresis to rule out myeloma
4) biopsy
- aspiration of abdominal fat pad (first line)
- myocardial biopsy (last resort)
5) 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]
Special laboratory:
1) Electrocardiography:
- low QRS voltage
2) Echocardiography
a) increased ventricular wall thickness
b) no cavity dilatation
c) granular appearance of ventricular myocardium
d) atria are usually dilated
e) cardiac valves may be thickened
f) mitral & tricuspid regurgitation is common
g) prolonged ventricular relaxation in early stages with important contribution to ventricular filling from atrial contraction
h) 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:
- cardiac sarcoidosis
Management:
1) colchicine for familial forms of cardiac amyloidosis
2) treatment of light chain amyloidosis (AL amyloidosis)
3) intermittent combination of prednisone & melphalan
- most successful when initiated prior to onset of heart failure & when myeloma is present
4) disease recurs in cardiac transplants within 2 years
5) stem cell transplantation may be an option for patients with AL amyloidosis identified before the onset of heart failure
6) mean survival of untreated patients with heart failure is 6 months
Related
restrictive cardiomyopathy
Specific
transthyretin cardiac amyloidosis; amyloid transthyretin cardiomyopathy (ATTR-CM)
General
amyloidosis
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 54-55
- Medical Knowledge Self Assessment Program (MKSAP) 11, 17, 18, 19.
American College of Physicians, Philadelphia 1998, 2015, 2018, 2022.