Aetiology of RCM:
Infiltrative cardiomyopathies are characterized by the deposition of abnormal substances that cause the ventricular walls to become progressively rigid, thereby impeding ventricular filling.
>Amyloidosis: is the most common cause in the western world and, apart from diastolic, may also cause systolic ventricular abnormalities.
>Sarcoidosis: affects the basal septum, atrioventricular node and His bundle, focal regions in the ventricular free walls, and the papillary muscles.
>Fabry’s disease: is an X-linked autosomal recessive disease that results from the progressive accumulation of glycosphingolipids due to lysosomal alpha-galactosidase deficiency. Affected patients have microvascular disease of the kidneys, heart, and brain. Cardiac involvement is not manifested until the third or fourth decade of life.
>Primary (idiopathic) restrictive cardiomyopathy: is expressed morphologically as myocyte hypertrophy and interstitial fibrosis.
>Endomyocardial fibrosis and Löffler’s endocarditis (eosinophilic cardiomyopathy): are the main causes of obliterative cardiomyopathy. They are both associated with eosinophilia (>1.5 × 10 9 /L for, at least, 6 months) that is either primary (Loffler’s) or secondary due to parasitic infections, lymphomas, or vasculitis.
>Carcinoid heart disease occurs as a late complication of the carcinoid syndrome in up to half of cases, with tricuspid regurgitation as the predominant lesion. The development of cardiac lesions is correlated with circulating levels of serotonin and its principal metabolite 5-hydroxyindoleacetic acid.
>Anthracyclines: can cause dilated cardiomyopathy or endomyocardial fibrosis. Diastolic dysfunction may persist, even years, after therapy with anthracyclines.
>Chloroquine and hydroxychloroquine in large cumulative doses may cause skeletal myopathy and restrictive cardiomyopathy