Not all big hearts are the same.  Cardiomyopathy may result from various genetic or environmental factors.  Not ALL thick hearts are Hypertrophic Cardiomyopathy, some have been called "mimickers" or phenocopies.  It is important to know WHY your heart is thick and genetic testing, review of symptoms and family history may lead you to treatment options that are targeted at the reason YOUR heart is thick.


HCM phenocopies

• Can look just like HCM

• Are important to identify

• Have a different disease course

• Have systemic manifestations

• May have potential targeted treatment

Elliott PM et al. 2014 ESC Guidelines on diagnosis and management of hypertrophic cardiomyopathy: the Task Force for the Diagnosis and

Management of Hypertrophic Cardiomyopathy of the European Society of Cardiology (ESC). Eur Heart J. 2014 Oct 14;35(39):2733-79.

Why do hearts become thick?

  • Amyloidosis

    Amyloidosis is rare, and there are several types. Two types, ATTR and AL, can cause a thick heart like HCM. About half of all amyloidosis patients have heart involvement. ATTR amyloidosis looks the most like HCM. Some "HCM patients" may actually have amyloidosis. Other body parts can be affected, including the liver, kidneys, brain, nerves, gut, tendons, and spine.


  • Danon Disease

    Danon Disease is very rare. Up to 4% of "HCM patients" actually have Danon Disease. Most people with Danon have heart problems. Danon also affects the liver, skeletal muscles, and eyes. It can cause developmental delay, learning disabilities, and mood disorders.

  • Fabry Disease

    Fabry Disease is rare. There are classic and late-onset forms. About half of Fabry Disease patients have heart involvement. Late-onset Fabry includes "HCM appearance" in half of male patients and a third of female patients. Fabry affects body parts including the kidneys, brain, gut, lungs, eyes, ears, and nerves.

  • Friedreich's Ataxia

    Friedreich's Ataxia (FA) is very rare. More than half of adults with FA have heart problems, often "HCM". FA also causes muscle weakness, speech problems, spinal issues, diabetes, hearing loss, and vision loss. The muscle weakness is significant in these patients.

  • Pompe Disease

    Pompe Disease is very rare. It is usually diagnosed in infancy, but it can be diagnosed later. Almost all cases of Infantile Pompe involve the heart, with 92% having the appearance of HCM. About 12 of every 100 adult Pompe patients have a heart problem, usually "HCM". Pompe also causes muscle weakness, skeletal problems, gut problems, and hearing issues.  

  • PRKAG2

    PRKAG2 Syndrome is very rare. About 1 of 100 "HCM" cases is caused by PRKAG2 Syndrome. Up to 70% of those with PRKAG2 have heart disease. It affects other body parts, such as the brain, liver, kidneys, pancreas, and muscles. The name is based on the gene that causes this syndrome.

  • RASopathies

    RASopathies are rare and include several different conditions. The most common is Noonan Syndrome. These syndromes are typically found in childhood, but later diagnosis is possible. Most RASopathy patients (up to 80%) have heart problems, including congenital heart defects and "HCM". Other organs and systems are affected, such as the face, head, and kidneys. Those with RASopathies may have slow growth, developmental delay, and bleeding disorders.

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