New HRS Consensus on Arrhythmogenic Cardiomyopathy

Debra L Beck

May 30, 2019

SAN FRANCISCO — The Heart Rhythm Society (HRS) has released their first-ever set of comprehensive recommendations on the diagnosis and treatment of arrhythmogenic cardiomyopathy.

In this consensus statement, the term arrhythmogenic cardiomyopathy, or ACM, refers to an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. The designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, and left ventricular noncompaction.

In an interview with theheart.org | Medscape Cardiology, document chair Jeffrey A. Towbin, MS, MD, explained that the change in nomenclature is part of an effort to incorporate a wider spectrum of genetic, systemic, and inflammatory disorders than previously considered as arrhythmogenic cardiomyopathies.

"We've now taken a broader view and put under the ACM umbrella a number of diseases that are arrhythmogenic disorders of the myocardium characterized by a clinical presentation with documented or symptomatic arrhythmia as a distinguishing feature, and where the diagnostics and therapeutics may or may not be similar," he said.

Towbin is the chief of cardiology at Le Bonheur Children's Hospital and St. Jude Children's Research Hospital, Memphis, Tennessee.

"Also, the only data we have are on dilated cardiomyopathy, but under that umbrella, we had some patients who had arrhythmias but were not considered anything other than garden-variety dilated cardiomyopathy and heart failure. So, this new nomenclature has subdivided that group and puts the arrhythmogenic forms under the umbrella of arrhythmogenic cardiomyopathy and leaves garden-variety dilated cardiomyopathy as a completely separate entity," added Towbin.

The consensus statement was released at the HRS 2019 Scientific Sessions and published online May 9 in Heart Rhythm.

Among the specific recommendations highlighted in an HRS press release is the indication for genetic testing of all disease-associated genes and variants in patients and decedents. Also recommended is genetic counseling that includes consideration of a three-generational family history.

"We want to encourage cardiologists to utilize genetic counselors to evaluate the data and present that information to families and to do the genetic cascade testing in at-risk first-degree relatives when a pathogenic or likely pathogenic variant has been identified in the proband, because this is their knowledge base and what they are good at," said Towbin.

The consensus statement also addresses briefly the many complex medical, legal, and psychological issues in cascade testing for familial variants in children.

Exercise Restriction in ARVC

Exercise is a topic that the statement writers directly addressed and that should, Towbin said, clear up some confusion on the topic.

Specifically, the authors reviewed the compendium of data and suggested that there is "a compelling case" to say that a dose-dependent relationship exists between exercise exposure and arrhythmogenic right ventricular cardiomyopathy (ARVC) onset (penetrance) and severity.

"The issue with arrhythmogenic cardiomyopathy, specifically ARVC, is it turns out that when they do a lot of sports, progression of the disease is faster and more severe, they end up with an earlier onset of disease, a more severe disease, and a greater risk of sudden cardiac death," said Towbin.

Recommendations for exercise restriction in patients with a clinical diagnosis of ARVC and for patients with positive genetic testing for ARVC without phenotypic expression are provided in the document.

In the first group, individuals with ARVC should not participate in "competitive or frequent high-intensity endurance exercise," whereas those testing positive but who are phenotype-negative should be counseled that competitive or frequent high-intensity endurance exercise "is associated with increased likelihood of developing ARVC and ventricular arrhythmias," the authors write.

"It's a mechanical stress problem," said Towbin. "When you have a weakened heart muscle and you keep banging away with high heart rate, high blood pressure, it basically just speeds up the development of fragile abnormal cells, such that over time you're going to see more and more scarring."

ICD Recommendations

Recommendations for implantable converter defibrillator (ICD) placement for primary and secondary prevention of sudden death in patients who have suffered a cardiac arrest or sustained ventricular tachycardia or ventricular fibrillation are made, in some cases broken down by specific conditions.

Left ventricular noncompaction is given special attention in this regard. "There have been a small number of papers that have talked about the arrhythmias associated with certain types of noncompaction and they indicate that maybe an ICD is useful to do in these patients — maybe for primary prevention, maybe secondary prevention — but there haven't been any specific guidelines. So, in this document we make recommendations as to which patients have a class I or lesser reason for putting in a device," explained Towbin.

"Moving forward, we need to focus on new approaches to better understand the mechanisms responsible for the development and progression of the disease," said document vice-chair William J. McKenna, MD, DSc, University College London, Institute of Cardiovascular Science, London, in an HRS press release. "Then novel treatment options can potentially be designed and tested."

He added that gene editing might provide a new means of treating these disorders now categorized under the umbrella of arrhythmogenic cardiomyopathy.

The consensus statement was developed in collaboration, endorsement pending, with the American College of Cardiology (ACC), the American Heart Association (AHA), the American Society of Echocardiography (ASE), the Asia Pacific Heart Rhythm Society (APHRS), the European Heart Rhythm Association (EHRA), the Heart Failure Society of America (HFSA), the International Society for Heart & Lung Transplantation (ISHLT), the Japanese Heart Rhythm Society (JHRS), the Latin American Heart Rhythm Society (LAHRS), the National Society of Genetic Counselors (NSGC), the Pediatric & Congenital Electrophysiology Society (PACES), and the Sociedade Brasileira de Arritmias Cardíacas (SOBRAC). Towbin reported no conflict of interest.

Heart Rhythm. Published online May 9, 2019. Abstract

Heart Rhythm Society 2019 Scientific Sessions (HRS): Session S-SP18. Presented May 9, 2019.

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