Restrictive cardiomyopathy (RCM)

Restrictive cardiomyopathy is rare in adults, and population‑level data remain limited due to diagnostic complexity and overlap with other cardiomyopathy phenotypes. In children, the estimated incidence is approximately 0.0003% and represents one of the least common but most severe paediatric cardiomyopathies.

The genetic conditions associated with RCM follow heterogeneous inheritance patterns. Autosomal dominant transmission is most frequently reported for primary sarcomeric RCM, with autosomal recessive and X-linked forms also described across the spectrum. Genetic and non-genetic factors both contribute to RCM, and a significant proportion of cases remain of unknown aetiology.

Diagnosis relies on a systematic evaluation including clinical examination, ECG, echocardiography, and cardiac magnetic resonance imaging. Echocardiography is the primary diagnostic tool and provides assessment of diastolic dysfunction, although truly restrictive physiology is often evident only in advanced disease. Cardiac MRI helps to distinguish RCM from constrictive pericarditis and identifies myocardial fibrosis or metabolic and inflammatory causes. Cardiac catheterisation is recommended when the diagnosis remains uncertain and is essential for transplant evaluation, particularly to assess pulmonary vascular resistance. Endomyocardial biopsy is useful in specific scenarios, including desminopathies, iron overload, lysosomal storage diseases, and mitochondrial disorders.

• Where RCM is suspected to have a genetic cause, molecular genetic testing can identify the underlying condition and confirm a clinical suspicion.
• The identified entity guides further clinical management and is a prerequisite for targeted medical care; therapeutic options are evaluated individually by the treating physicians.
• Identification of the underlying pathogenic germline variant enables predictive testing of at-risk family members and provides information relevant to family planning.

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