What is Arrhythmogenic Cardiomyopathy?

Arrhythmogenic cardiomyopathy is a disease of the heart muscle. It is a defect in the tiny proteins that hold the heart muscle cells together. These complex proteins or “desmosomes” can be disrupted in ACM, leading to areas of scarring and fatty deposits. These areas of scarring may lead to abnormal and dangerous heart rhythms.

ACM is often an inherited condition that is slightly more common in males than females. The right ventricle is more susceptible to this damage, though the left ventricle can also be involved. ACM is divided into right predominant ACM (Arrhythmogenic Right Ventricular Cardiomyopathy or ARVC), and left (ALVC) or both (biventricular predominant ACM).

Effects and Symptoms

The first signs of ACM may be subtle and easily missed. Some symptoms are nonspecific like fatigue, light-headedness, chest pain and abdominal pain. Some can have palpitations or a feeling of abnormal heart beats, fainting or seizure-like activity and in severe cases, sudden cardiac arrest.

The fatty depositions in heart muscle cells, as they progress, cause the heart to enlarge and function or squeeze poorly. The disruptions in heart muscle cells and areas of scarring can also cause an abnormal heart rhythm called ventricular tachycardia.

Endurance exercise allows ACM to progress faster and increases the risk of abnormal ventricular rhythm, increasing the risk of sudden cardiac arrest.

Diagnosis

ARVC is a difficult condition to diagnose, and it is usually first found when a patient has an abnormal heart rhythm. 

Testing includes ECGs, signal average ECGs, Holter monitor and stress tests to evaluate heart rhythm at rest and during activity. An echocardiogram can demonstrate chamber enlargements and changes in function. A cardiac MRI is a good way to visualize changes in the heart that can occur with ACM. It can evaluate the tissue composition of the heart and how well it is functioning. 

Electrophysiological testing is done in some patients to identify the part of the heart that is causing the irregular heart beat, to assess the risk of future episodes and to determine if the patient is a candidate for an implantable cardioverter defibrillator (ICD), or radiofrequency catheter ablation that can target and eliminate a source of abnormal rhythm in the heart. Cardiac catheterization is also performed at times in order to remove a small piece of heart tissue for a biopsy. 

Genetic testing is offered to those who are clinically identified to have ACM. If genetic testing identifies a genetic cause for ACM, genetic testing can be offered to first degree relatives (a parent, sibling or child) to determine if they have the same gene. Genetic counselors help families cope with the results and the interpretation of these tests.

Management and Treatment

ACM is a long-standing and progressive condition. Treatments can slow the progression of symptoms and abnormal rhythms, improving the quality of life for patients. Beta blockers can control symptoms of palpitations and reduce the chance of a cardiac event. Additional antiarrhythmic medications may be added for those who have a high burden of abnormal rhythms. Taking medications regularly is very important. 

Some patients are advised to have an ICD implanted to stop potentially fatal heart rhythms.An ICD can detect abnormal rhythms and deliver a shock when needed. An ICD, while potentially lifesaving, has associated risks and complications. The decision for ICD implantation includes careful assessment and family discussion. 

Exercise increases the risk for abnormal heart rhythms and hastens the progression of the disease. Exercise restriction plays an important role in management, even once on appropriate medications. 

Because of the risk of sudden cardiac arrest, it is recommended that family members of people with ACM take CPR courses so they are able to respond if their loved one should have an episode at home. Ideally, sports events and exercise are supervised with AED (Automated External Defibrillator) and CPR-trained companions present in case of a cardiac arrest.

Adult and Adolescent Management

Dangerous arrhythmias are more likely to occur with exercise. Strenuous and competitive sports are not recommended for individuals with ARVC. The care team can provide exercise recommendations that are tailored to an individual. Regular follow up and prescribed medications is very important. It is also important to stay in shape without increasing the risk.

Women of child-bearing years are counseled about contraceptives and pregnancy. Pregnancy is generally tolerated well in women with ACM, but may have bad effects in the long-term for those who have symptoms and poor heart function.