Overview

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Cardiomyopathy (kahr-dee-o-my-OP-uh-thee) is a broad term for a group of diseases that affect the heart muscle. The muscular walls of the heart’s chambers can become stretched, thickened and stiff.  This changes their size, shape and ability to efficiently pump blood around the body.

There are various types of cardiomyopathy. The main types include dilated, hypertrophic and restrictive cardiomyopathy. Treatment includes medicines and sometimes surgically implanted devices and heart surgery. Some people with severe cardiomyopathy need a heart transplant. Treatment depends on the type of cardiomyopathy and how serious it is.

Histiocytoid Cardiomyopathy (HICMP) is an ultra-rare*, genetic cardiac disorder, primarily affecting newborns and young children, particularly girls. It's characterised by severe cardiac arrhythmias, dilated cardiomyopathy, and can lead to sudden death. The disorder is marked by the presence of histiocyte-like cells within the heart muscle, as well as nodules in the myocardium and endocardium. 

Key Features:

• Genetic Predisposition: HICMP is believed to have a genetic basis, with a higher prevalence in females. 
• Clinical Presentation: Symptoms typically appear in infancy or early childhood and include severe arrhythmias, dilated cardiomyopathy, and potentially sudden death. 
• Pathological Features: The heart muscle exhibits abnormal myocytes, including histiocyte-like cells with increased mitochondria. Nodules may also be present in the myocardium, endocardium, and valves. 
• Mitochondrial Involvement: HICMP is often associated with mitochondrial dysfunction and mutations in mitochondrial genes. 
• Treatment: Early diagnosis and treatment are crucial. Surgical excision of nodules may be an option to treat arrhythmias, and heart transplantation has been considered in some cases. 
• Prognosis: The prognosis for HICMP is generally poor, with many cases being fatal. 

* In the UK, an ultra-rare disease is typically defined as a condition affecting fewer than 1 in 50,000 people. This definition is often used by organizations like the National Institute for Health and Care Excellence (NICE) and the Scottish Medicines Consortium (SMC). 

At the time of writing, there have only been circa. 150 cases noted globally to date.