Arrhythmogenic Cardiomyopathy (ACM) is a type of heart disease where parts of the heart muscle are replaced by fatty and fibrous (scar) tissue. This weakens the heart and can disrupt its ability to pump blood effectively. ACM primarily affects the ventricles—the lower chambers of the heart that pump blood to the lungs and the rest of the body.

ACM was previously known as Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) because it was thought to only involve the right ventricle. However, research has shown that ACM can affect either ventricle or both. Importantly, the upper chambers of the heart (the atria) are not affected.

This condition occurs because of a defect in the proteins that hold heart muscle cells together. When these proteins do not form correctly, the heart muscle cells can detach and die. As a result, the body replaces the damaged cells with scar tissue and fat. Over time, this replacement process weakens and stretches the heart muscle, leading to abnormal heart rhythms (arrhythmias) and reducing the heart’s ability to pump blood efficiently.

Arrhythmogenic Cardiomyopathy (ACM) is a condition that can be caused by genetic changes (variants) affecting proteins critical to the structure and function of the heart muscle. These include desmosomal proteins, which are essential for the adhesion between heart muscle cells, helping the heart maintain its strength and rhythm.

ACM is usually inherited in an autosomal dominant manner, meaning a person needs only one copy of the altered gene from one parent to potentially develop the condition. The most common genetic cause of familial ACM is variants in the PKP2 gene. Other genes, such as DSG2, DSP, and JUP, have also been linked to the condition.

While genetic testing can help identify ACM, it is not always necessary for diagnosis. Clinical features, such as arrhythmias, abnormal findings on an electrocardiogram (ECG), imaging studies (e.g., echocardiogram or cardiac MRI), and family history, are often used to diagnose the condition.

In some cases, ACM may not be inherited. It can result from other factors, such as viral infections or inflammation, which damage the heart muscle over time.

The Cardiac Society of Australia and New Zealand (CSANZ) has released a Position Statement on the Diagnosis and Management of Arrhythmogenic Right Ventricular Cardiomyopathy (2019 Update). This document is written for clinicians, not patients, but is included here for those who wish to explore more technical information about ARVC.