Cardiac amyloidosis
Description
- Extracellular deposition of misfolded protein as beta-pleated sheet amyloid fibrils in the myocardium -> infiltrative, restrictive cardiomyopathy
- Presents as HFpEF with increased wall thickness, not a dilated ventricle
The two types that matter
| AL (light chain) | ATTR (transthyretin) | |
|---|---|---|
| Precursor | Monoclonal free light chains from a plasma cell clone | Transthyretin (liver-derived) |
| Subtypes | - | Wild-type (ATTRwt) - elderly men; hereditary (ATTRv) - V122I, T60A, V30M |
| Age | 50-70 | ATTRwt >70; ATTRv variable |
| Cardiac wall thickness | Modest | Often marked (>15-18 mm) |
| Troponin/NT-proBNP | Disproportionately high for wall thickness | Raised |
| Extracardiac | Macroglossia, periorbital purpura, nephrotic proteinuria, hepatomegaly, autonomic neuropathy | Carpal tunnel, lumbar spinal stenosis, biceps tendon rupture, polyneuropathy |
| Tempo | Rapidly progressive | Indolent over years |
| Untreated median survival with HF | ~6 months | 2-6 years |
- *AL is a haematological emergency; ATTR is a chronic cardiology problem*
Clinical picture
- HFpEF with right heart failure often predominating - raised JVP, ascites, congestive hepatomegaly, peripheral oedema
- Atrial fibrillation and conduction disease - very common
- Hypotension, or "normalisation" of previously hypertensive blood pressure - a hypertensive patient whose BP drifts down and whose antihypertensives are being stopped is a classic presentation
- Exertional syncope (fixed stroke volume, autonomic failure)
- Angina with unobstructed coronaries (microvascular amyloid)
- Advanced: low output, cachexia
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