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ATTR-CM (cardiomyopathy) vs ATTR-PN (peripheral neuropathy)

 

Over the course of the past few months, we spent time discussing two of the most common hallmark symptoms of ATTR amyloidosis: cardiomyopathy and peripheral neuropathy. In this article, we’ll briefly recap both hallmark symptoms as well as bring it all together by discussing the two most common forms of ATTR amyloidosis: ATTR cardiomyopathy (ATTR-CM) and ATTR peripheral neuropathy (ATTR-PN).

To recap …

 

Cardiomyopathy

Cardiomyopathy is a broad term that is used to describe disease of the heart muscle, making it difficult for the heart to provide the body with an adequate blood supply. It is a common cause of sudden cardiac arrest and sudden cardiac death, which can lead to heart failure and even death. 

Types of Cardiomyopathy:

  • Dilated Cardiomyopathy → dilation of the left ventricle prevents the heart from pumping effectively
  • Hypertrophic Cardiomyopathy → abnormal thickening of the heart muscle most commonly surrounding the left ventricle
  • Restrictive Cardiomyopathy → stiffening of the heart muscle results in an inelasticity
  • Arrhythmogenic Right Ventricular Dysplasia → scar tissue replaces healthy tissue of the right ventricle
  • Unclassified Cardiomyopathy → all other forms of cardiomyopathy fall within this category

 

Peripheral Neuropathy

Peripheral neuropathy, also referred to as polyneuropathy, is a very broad term used to describe damage of the peripheral nerves. Damage to these nerves most commonly causes numbness, pain, and weakness but can affect other areas of the body including, but not limited to, circulation, digestion, and urination. 

Types of Neuropathy:

  • Motor Neuropathy → damage to the motor nerves 
  • Sensory Neuropathy → damage to sensory nerves 
  • Autonomic Nerve Neuropathy → damage to autonomic nerves that control involuntary functions 
  • Combination Neuropathies → damage to a mix of 2 or 3 of these other types of neuropathies

 

ATTR Amyloidosis

The origin of this disease can be genetic (hATTR) or non-genetic, or “wild-type” (ATTRwt). Regardless, in ATTR amyloidosis, the transthyretin (TTR) protein is misfolded and aggregates, forming amyloid fibers that deposit into tissues and organs. The deposition of protein causes organ dysfunction and can even cause organ failure and death. 

 

ATTR-CM and ATTR-PN

Depending on the location of protein deposition, the disease is referred to in different ways. For instance, when the primary location of amyloid deposit is in the heart, the disease is referred to as ATTR cardiomyopathy (ATTR-CM). On the other hand, when the primary location of amyloid deposit is in the nerves, the disease is referred to as ATTR peripheral neuropathy (ATTR-PN).

ATTR-CM impairs the heart’s ability to pump effectively. A major challenge surrounding this disease is that symptoms of ATTR-CM are often similar to other heart conditions like enlarged heart and heart failure. This makes diagnosing the disease increasingly more difficult. Individuals with hATTR typically present symptoms in their 50s and 60s, whereas those with ATTRwt may not present symptoms until their 70s and later. 

Common Symptoms of ATTR-CM:

  • Fatigue
  • Swelling of legs, ankle, or abdomen
  • Shortness of breath with activity
  • Orthostatic hypotension
  • Difficulty breathing when lying down
  • Arrhythmia

ATTR-PN impairs the function of the nervous system. While amyloid most commonly builds up in the peripheral nervous system, deposition can also occur in the autonomous system. This results in a diversity of symptoms that are specific to the site of amyloid deposition. Symptom presentation is much more diverse, occurring as early as the 20s, or as late in life as the 70s. 

Common Symptoms of ATTR-PN:

  • Carpal tunnel syndrome
  • Diarrhea and/or constipation
  • Nausea, vomiting
  • Loss of appetite
  • Sexual dysfunction
  • Muscle weakness
  • Eye problems
  • Orthostatic hypotension

Expert Insights – Cardiac Clues and Clinical Signs

In part 1 of a 2-part series, Dr. Keyur Shah, cardiologist from VCU Health’s cardiac amyloidosis care team, discusses the two most common types of transthyretin (TTR) amyloidosis: hereditary and wild-type. He details how ATTR cardiomyopathy amyloidosis presents and manifests itself to impair the heart. Dr. Shah lists clinical clues, “red flags,” and biomarkers which can raise suspicion of the presence of amyloidosis. Next, he discusses insights that can be gained from echocardiograms, electrocardiograms, and cardiac MRIs and how they offer possible indicators of the disease presence. Once amyloidosis is suspected, definitive diagnosis testing is next.

 

In part 2 of a 2-part series, Sarah Paciulli, Heart Failure Nurse Practitioner, from VCU Health’s cardiac amyloidosis care team, continues from where Dr. Keyur Shah ended in Part I and discusses here in Part II the non-cardiac clues of transthyretin (TTR) amyloidosis. She expands the list of clinical clues and “red flags” that clinicians should be alert to, including orthopedic manifestations, erectile dysfunction, and polyneuropathy.

 

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References:

https://www.pfizer.com/news/articles/understanding_this_rare_disease_called_attr_amyloidosis

https://www.mayoclinic.org/diseases-conditions/cardiomyopathy/symptoms-causes/syc-20370709

https://www.yourheartsmessage.com

https://healthjade.net/familial-amyloidosis/

https://my.clevelandclinic.org/health/diseases/14737-neuropathy

https://www.hopkinsmedicine.org/health/conditions-and-diseases/peripheral-neuropathy

https://www.mayoclinic.org/diseases-conditions/peripheral-neuropathy/symptoms-causes/syc-20352061

https://practicalneurology.com/articles/2021-july-aug/neuromuscular-amyloidosis

https://healthjade.net/familial-amyloidosis/



Cardiac Clues that Suggest Transthyretin Amyloidosis – Part I

In part 1 of a 2-part series, Dr. Keyur Shah, cardiologist from VCU Health’s cardiac amyloidosis care team, discusses the two most common types of transthyretin (TTR) amyloidosis: hereditary and wild-type. He details how ATTR cardiomyopathy amyloidosis presents and manifests itself to impair the heart. Dr. Shah lists clinical clues, “red flags,” and biomarkers which can raise suspicion of the presence of amyloidosis. Next he discusses insights that can be gained from echocardiograms, electrocardiograms, and cardiac MRIs and how they offer possible indicators of the disease presence. Once amyloidosis is suspected, definitive diagnosis testing is next.  See Part II: “Clinical Signs that Suggest Transthyretin Amyloidosis: Non-cardiac Clues” for more information.

Clinical Signs that Suggest Transthyretin Amyloidosis: Non-cardiac Clues – Part II

In part 2 of a 2-part series, Sarah Paciulli, Heart Failure Nurse Practitioner from VCU Health’s cardiac amyloidosis care team, continues from where Dr. Keyur Shah ended in Part I and discusses here in Part II the non-cardiac clues of transthyretin (TTR) amyloidosis. She expands the list of clinical clues and “red flags” that clinicians should be alert to, including orthopedic manifestations, erectile dysfunction, and polyneuropathy.  See Part I: “Cardiac Clues that Suggest Transthyretin Amyloidosis” for more.

 

Closing the Underdiagnosis Gap of Transthyretin Cardiac Amyloidosis Among African Americans

Dr. Kevin Alexander, advanced heart failure and transplant cardiologist at the Stanford Amyloid Center, discusses transthyretin cardiac amyloidosis (ATTR-CM) and how today this is a “common rare disease,” more prevalent than previously appreciated. He summarizes findings from a study to understand diagnosis across the U.S. and how ATTR-CM disproportionately affects black individuals. This statistic is driven by the belief that 3-4% of African descendants carry the V122I TTR variant – translating to over 1 million carriers. Kevin offers a screening algorithm for who to screen for ATTR-CM, and examines sub-groups of African Americans that are important not to overlook.

Expert Insights: The Future for Patients with Transthyretin Cardiac Amyloidosis is Looking Brighter

The treatment for patients with Transthyretin Cardiac Amyloidosis has advanced significantly since 2018 when there were no FDA-approved therapies. In this presentation, Dr. Mat Maurer from Columbia University shares how diagnostic imaging techniques have significantly improved, thereby reducing the need for an invasive heart biopsy. In addition, he shares fascinating statistics on how the age and stage of diagnosis has been evolving. Based on today’s clinical trials, providers are optimistic that the expansion of options for patient care will continue.

The future is indeed looking brighter.

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