Miocardiopatía amiloide por transtiretina (MC-ATTR)

¿Qué es la miocardiopatía amiloide por transtiretina?

Transthyretin (trans-thy-re-tin) amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed and potentially fatal disease of the heart muscle. In ATTR-CM, a protein called transthyretin that normally circulates in the bloodstream becomes misshapen and builds up in the heart, nerves and other organs. 

When these amyloid deposits build up in the heart, the walls can become stiff, making the left ventricle unable to properly relax and fill with blood – called cardiomyopathy. As the condition progresses, the heart can become unable to adequately squeeze to pump blood out of the heart, ultimately leading to heart failure.

MC-ATTR hereditaria

There are two types of ATTR-CM. In hereditary ATTR-CM (hATTR-CM), which can run in families, there’s a variant in the transthyretin gene, which results in amyloid deposits in the heart, nerves and sometimes the kidneys and other organs. Symptoms may start as early as age 20 and as late as 80. 

Hereditary ATTR-CM is more common in localized parts of Portugal, Sweden and Japan; however, there are a number of variants in different parts of the world. Some variants are more common in people of Irish ancestry while others are common among people of African descent. 

Different variants may progress in a different way and involve different organs. The most common variant in the United States occurs in 1 in 25 of all African Americans and in older patients who may be misdiagnosed with high blood pressure-related heart disease.

Genetic testing may provide important information to developing a treatment plan. 

MC-ATTR de tipo natural

The second type is wild-type ATTR-CM (wATTR-CM), in which there is no variant in the transthyretin gene. Wild-type ATTR-CM doesn’t run in families. It most commonly affects the heart and can also cause carpal tunnel syndrome and pain and numbness in the hands and feet, called peripheral neuropathy. Symptoms usually start after age 65. 

¿Cuáles son los factores de riesgo?

Risk factors for hereditary ATTR-CM include:

• Un miembro de la familia con MC-ATTR o insuficiencia cardíaca
• 50 años o más (aunque los síntomas pueden comenzar desde los 20 hasta los 80 años)
• Sexo (los pacientes son principalmente de sexo masculino)
• Raza: afroamericana

Entre los factores de riesgo para la MC-ATTR de tipo natural se encuentran:

• 65 años en adelante
• Sexo (los pacientes son principalmente de sexo masculino)

¿Cuáles son los síntomas?

Los síntomas de la MC-ATTR pueden variar o ser sutiles, y a menudo la afección se diagnostica erróneamente. En sus primeras etapas, puede imitar los síntomas de otras afecciones, tales como insuficiencia cardíaca relacionada con la presión arterial alta, o hipertensión, y agrandamiento y engrosamiento del corazón, o miocardiopatía hipertrófica. Es posible que algunos pacientes no presenten síntomas, mientras que otros pueden progresar a insuficiencia cardíaca en estado terminal. Los síntomas de la MC-ATTR de tipo natural pueden ser leves y permanecer sin diagnosticar.

Los síntomas de la MC-ATTR son similares a aquellos asociados con la insuficiencia cardíaca.

Shortness of breath is the most common, especially with minimal exertion and when lying down.

Other symptoms usually occur after the shortness of breath is already there, including:

• Tos o sibilancias, especialmente cuando se acuesta boca abajo.
• Hinchazón en los pies, tobillos y piernas
• Hinchazón en el abdomen
• Confusión o dificultad para pensar
• Aumento de la frecuencia cardíaca
• Palpitaciones o ritmos cardíacos anormales

Additional symptoms for ATTR-CM may include:

• Entumecimiento u hormigueo en las manos y los pies (MC-hATTR)
• Síndrome del túnel carpiano (MC-wATTR)

¿Cómo se diagnostica?

Es posible que se sospeche que padece MC-ATTR debido a los síntomas típicos y a los resultados de una prueba cardíaca de rutina: un electrocardiograma o ecocardiograma. Una vez bajo sospecha, se necesitan pruebas más especializadas para confirmar el diagnóstico. Entre estas podrían encontrarse:

• Estudios por imágenes del corazón, más comúnmente una RM cardíaca y/o una exploración de medicina nuclear del corazón
• Una biopsia de tejido de un órgano afectado
• Pruebas genéticas 

¿Cómo se puede tratar la MC-ATTR?

There are several promising new therapies for ATTR-CM on the horizon or available, so it is important to talk to your health care professionals about treatment options. 

With ATTR-CM, health care professionals focus on easing the heart failure symptoms and slowing or stopping the amyloid deposits. Medications are approved for hereditary transthyretin amyloidosis affecting the nerves, causing a condition called neuropathy.

In cases of advanced heart failure, heart transplantation may be an option. Because the abnormal transthyretin protein is produced by the liver, some patients may require both heart and liver transplantation.  

Hable con sus profesionales de cuidado de la salud

Awareness of ATTR-CM among health care teams is low. In fact, it’s often misdiagnosed as hypertensive heart failure or hypertrophic cardiomyopathy and may already be advanced by the time the patient receives a diagnosis. 

If you are living with heart failure and have additional unresolved or seemingly unrelated symptoms, speak to your health care professional about your symptoms and treatment options. Starting that conversation could be a lifesaver. 

Tell your doctor about any shortness of breath and ask for a diagnostic testing and treatment plan. If the diagnostic tests don’t provide an answer, or if the treatment fails to improve your symptoms, talk with your health care professional about next steps. It’s important not to give up until the tests reveal a diagnosis and the treatment relieves your symptoms. 

If you do have ATTR-CM, genetic testing may offer important information to your health care professional to develop a treatment plan. 

Obtenga ayuda

Getting support for you and your caregivers is important to your health. Research shows that going it alone and not seeking support during a heart diagnosis can reduce your ability to make the lasting changes you need to live a longer, healthier life. 

Learn more about ATTR-CM and connect with others impacted by this form of cardiomyopathy on the American Heart Association’s Support Network. There, you will find a community triumphing over their health obstacles each day. 

You can share your experience to help others and get support from others who have been there. Connect for free today at heart.org/SupportNetwork.