Take home pearls from the case:
- Restriction cardiomyopathy ddx includes genetic conditions (usually sarcomere disorders), infiltrative conditions (amyloid, sarcoid, fatty infiltration), storage diseases (hemochromatosis, glycogen storage and other (scleroderma, DM cardiomyopathy, radiation, cancer, and endomyocardial fibrosis)
- There are >25 types of amyloid (!) but the 3 most common are:
- AL – primary amyloidosis due to plasma cell dyscrasia producing monoclonal light chains (often affects the heart)
- ATTR – The familial or senile type, which involves a trans-thyretin mutation (some mutations affect the myocardium, others do not)
- AA – Secondary to chronic inflammatory disorders (rarely affects the myocardium)
- EKG will show low voltage in the limb leads only about 50% of those with cardiac amyloid, and usually in those with AL amyloid
- Definitive amyloid diagnosis is made on biopsy (endomyocardial, abdominal fat pad, rectum or kidney). However, cardiac MRI can strongly suggest the diagnosis if there is late global gadolinium enhancement in the LV.
- Abdominal fat pad biopsy is often the first biopsy site for amyloid because of ease of access. Rectal and bone marrow biopsies haves similar sensitivity (50-70%). Kidney and liver biopsies have 90% sensitivity, but are, of course, more invasive.
- Treatment consists of management of heart failure and treating the underlying cause of cardiomyopathy, if one is identified.
Many thanks to Rabih for sharing this framework for infiltrative disease processes!
4 + 3 rule: (4 cells, 3 molecules)
|Granulomas (lymphoma, sarcoid, TB)||Amyloid (multiple types)|
|Histiocytes (Langerhans, Erdheim Chester)||Iron (hemochromatosis)|
|Plasma cells (IgG 4)||Glycogen storage disease|
|Mast cells (systemic mastocytosis)|