Cardiomyopathies Caused by Rare Diseases

Cardiomyopathies are a group of diseases involving abnormal structure and function of the heart muscle. They may be triggered by toxic exposure, the use of certain narcotic substances, or as part of autoimmune and hormonal disorders. In such cases, they are referred to as secondary cardiomyopathies.

For proper diagnosis, several tests are typically performed, including echocardiography, ECG, endomyocardial biopsy, and cardiac catheterization.

Types of Cardiomyopathies

The American Heart Association has developed a very detailed classification of cardiomyopathies. At the first level, it distinguishes between primary and secondary cardiomyopathies, then lists a number of factors and diseases that cause each specific type.

Dilated Cardiomyopathy (DCM)

Characterized by dilation of the heart chambers and thinning of the ventricular walls. The myocardial fibers become stretched and weakened, leading to impaired systolic function and progressive heart failure, often involving both ventricles. Dilated cardiomyopathy may develop as a consequence of viral myocarditis, genetic mutations, or toxic injury (e.g., alcohol, chemotherapy).

Hypertrophic Cardiomyopathy (HCM)

A genetically determined disease caused by defects in the patient’s genetic code. In about 30% of cases, the exact cause remains unknown, and the disease may be asymptomatic. It is characterized by hypertrophy of the left ventricle. HCM is often associated with an increased risk of sudden cardiac death before the age of 40.

Restrictive Cardiomyopathy (RCM)

A genetically determined disease in most cases. Pathological changes prevent stretching of the heart muscle fibers and impair normal function, leading to difficulties filling the heart with blood. This is the rarest type of cardiomyopathy.

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

A rare cardiomyopathy with a genetic basis. This type significantly increases the risk of ventricular arrhythmias, is characterized by dilation of the right ventricle, and fatty degeneration of this heart chamber.

Cardiomyopathies and Rare Diseases

Certain rare diseases can cause or contribute to the development of cardiomyopathies. These conditions may directly affect the heart muscle or lead to systemic changes that damage cardiac tissue over time.

• Fabry disease: a lysosomal storage disorder caused by mutations in the GLA gene. It leads to the accumulation of globotriaosylceramide (Gb3) in various organs, including the heart, causing left ventricular hypertrophy, arrhythmias, and heart failure. 
• Amyloidosis: a group of diseases characterized by the accumulation of misfolded proteins (amyloid) in tissues. Cardiac amyloidosis leads to a stiff, noncompliant myocardium, resulting in restrictive cardiomyopathy and diastolic dysfunction. 
• Sarcoidosis: an inflammatory disease that can involve the heart, forming granulomas within the myocardium. Cardiac involvement may result in arrhythmias, heart block, or heart failure. 
• Hemochromatosis: a metabolic disorder that causes iron overload in the body. Excess iron deposits in the heart can lead to dilated or restrictive cardiomyopathy. 
• Mitochondrial diseases: rare genetic conditions affecting cellular energy production. The heart, with high energy demands, is particularly vulnerable, often leading to hypertrophic or dilated cardiomyopathy. 

Recognizing cardiomyopathy as a potential manifestation of a rare disease is crucial for early diagnosis and targeted treatment. In some cases, identifying the underlying genetic or metabolic cause may significantly alter prognosis and therapeutic options.

Symptoms of cardiomyopathies

Regardless of the primary cause or type, cardiomyopathies often present with similar symptoms, including:

• Chest pain
• Shortness of breath
• Dizziness
• Palpitations
• Weakness
• Recurrent fainting

Treatment

It depends strictly on the type of cardiomyopathy that has been diagnosed. Therapies include pharmaceuticals, which provide medications to relieve symptoms and regulate blood clotting, as well as surgical intervention. In extreme cases, heart transplantation may be necessary.

If you suspect having this condition, reach out to your doctor for proper guidance and care. 

Scientific References

• Ciarambino, T., Menna, G., & Sansone, G. (2021). Cardiomyopathies: An Overview. International Journal of Molecular Sciences, 22(14):7722
• Rare and Ultra-Rare Diseases as Causes of Cardiomyopathy. ABC Heart Failure & Cardiomyopathy, 3(1):e20230032.
• Genetics of the Cardiomyopathies: A Review for the Cardiologist. ABC Heart Failure & Cardiomyopathy, 4(3):e20240047