Etiology
- Amyloidosis (most common cause, AL or Transthyretin/ATTR). See ATTRmt amyloidosis
- Sarcoidosis (cardiac granulomas).
- Hemochromatosis (iron overload, can also cause dilated CM).
- Post-radiation therapy (e.g., prior breast/lymphoma tx).
- Rare causes: Löffler endocarditis (hypereosinophilic), endomyocardial fibrosis, scleroderma.
Pathophysiology
Infiltration (e.g., abnormal proteins, glycogen, eosinophils, granulomas, iron) or proliferation of connective or fibrotic tissue → ↓ elasticity of myocardium → ↓ ventricular compliance (severe diastolic dysfunction)
Clinical features
Diagnostics
Differ from Hypertrophic cardiomyopathy by EF = 25~50%, while restrictive cardiomyopathy > 60%