Introduction

• Cardiomyopathy (CM) is a group of heart muscle diseases that make it difficult for the heart to pump blood throughout the body, leading to heart failure and irregular heartbeats. Paediatric CM is found specifically in children as a rare occurrence, but once diagnosed, it carries a substantial risk of morbidity and mortality
• An arrhythmia (AM) is an irregular heartbeat where the heart beats too fast (tachycardia), too slow (bradycardia) or in an erratic pattern. These differences in beating are often due to a problem with the heart’s electrical signals
• Understanding the link between CM and AM is crucial since AMs are often a consequence of CM, which leads to significantly reduced quality of life or increased risk of fatality.¹ This connection enables healthcare providers to plan more effective treatments, improving prognosis and developing therapies that target the underlying CM causing AMs, thereby preventing severe complications and saving lives

Paediatric Cardiomyopathy: Overview

Main types of CM

• Dilated (DCM): The heart muscle stretches and becomes thin, so it pumps blood weakly
• Hypertrophic (HCM): The main chamber involved in pumping blood becomes unusually thick
• Restrictive (RCM): The heart muscle becomes stiff to the extent that it is unable to pump blood efficiently
• Arrhythmogenic (ACM): The once healthy heart muscle is scarred or has fatty tissue. It may affect the right side, left side, or both sides of the heart

Causes of CM

• Genetic: Occurs often within a family. Children with CM may have a close relative who also has heart disease. Changes (mutations) in certain genes can affect how the heart muscle works²
• Infections/illnesses (Acquired): Caused by infections such as myocarditis, immune system problems, or side effects of medication³
• Muscle and nerve disorders: A condition where muscular dystrophy weakens both muscles of the body and the heart⁴
• Metabolic problems: When the body is unable to efficiently produce energy or break down substances due to mitochondrial diseases or Pompe disease⁵
• Unknown (idiopathic): The exact cause remains unknown

Paediatric Arrhythmias: Overview

The two types of AMs include Tachyarrhythmias (fast rhythms) and Bradyarrhythmias (slow rhythms).

Tachyarrhythmias (fast rhythms)

• The heart beats faster than normal due to faulty electrical signals
• Supraventricular Tachycardia (SVT): Fast beating starting in the upper heart chambers
• Ventricular Tachycardia (VT): Fast beating starting in the lower chambers
• Symptoms include a fast heartbeat (palpitations), dizziness, chest pain, or shortness of breath
• Causes include lifestyle factors like stress, caffeine, or alcohol. Underlying health conditions such as heart disease, high blood pressure, anaemia and hyperthyroidism can also be a factor⁶

Bradyarrhythmia (slow rhythms)

• The heart beats more slowly than it should
• Atrioventricular block: The signal between the upper and lower chambers is delayed or blocked
• Sinus node dysfunction: The heart’s natural “pacemaker” does not work efficiently
• Causes include heart disease, oxygen starvation or side effects from medicines

Clinical Connections: How Cardiomyopathy Leads to Arrhythmia

CM affects the heart’s ability to pump blood and the heart’s intrinsic electrical system. Changes to the heart structure, such as thickening, dilation or scarring of the heart muscle, can disrupt the normal conduction pathways, preventing efficient pumping of blood. Additionally, genetic mutations can prevent muscle and electrical function. Collectively, these changes create an unstable electrical environment that increases the risk of AMs. These AMs range from mild palpitations to life-threatening occurrences like ventricular tachycardia, fibrillation, or collapse.⁷

Diagnosis and Evaluation

CM and AMs are often found during routine checkups or while investigating other health issues. Diagnosis can begin with a medical and family history, a physical exam, and listening to the heart rhythm. Tests may include:

• Blood tests to check for infection, medication effects, or imbalances
• Echocardiogram (Echo): Ultrasound imaging of the structure and functioning of the heart
• Electrocardiogram (ECG): Records the heart’s electrical activity at rest or during activity
• Holter monitor: Portable device worn for a few days to track changes in heart rhythms during daily life
• Electrophysiology study (EPS): A catheter-based test to locate faulty signals
• Implantable loop recorder (rare): Placed under the skin to monitor rhythms long-term

Management of cardiomyopathy and arrhythmias in children

Treatment for children with CM and AM depends on the type of condition and how severe it is. The treatment for CM typically involves an entire team of healthcare professionals who will work collaboratively to focus on controlling symptoms and protecting the long-term health of the heart.⁸

Generalised treatment options may include:

• Medication to help the heart pump efficiently and control fast or slow rhythms
• Monitoring through regular check-ups and genetic testing for the family
• Avoiding strenuous sports activities in high-risk children
• Diet changes that incorporate more nutritious food

Specific treatment options may include:

• Weak/enlarged hearts (DCM): Appropriate medication, devices, or heart transplant in severe cases
• Thick hearts (HCM): Appropriate medication, surgery, or defibrillators for high-risk children
• Stiff hearts (RCM): Appropriate medication or heart transplant
• Arrhythmias: Appropriate medication, catheter procedures, pacemakers, or defibrillators

Prognosis and Outcomes

• Outlook is dependent on the type of heart muscle problem, the severity of arrhythmias, age, genetics, and the patient’s response to treatment
• HCM: Higher risk of sudden cardiac-related death; long-term follow-up with a healthcare provider is needed
• ACM: Elevated risk of dangerous ventricular rhythms; strenuous exercise is discouraged
• DCM: Outcomes may vary. Some patients report an improvement, whilst others may require a heart transplant
• Arrhythmias: Some may be harmless, whilst others indicate a risk of heart failure
• Early detection and regular follow-ups help children stay healthy and achieve the best possible outcomes⁹

Summary

Paediatric CM is closely related to AMs, since structural changes of the heart disrupt normal electrical signals. These disruptions ultimately worsen heart failure, increase the risk of stroke and may cause cardiac death. Early diagnosis and customised treatment options can ensure a child lives a healthy, full life. Regular follow-ups and family support are important in supporting the child’s overall well-being. Ongoing research into CM and AM is paving the way forward to develop better treatment options for children with CM and AM.

FAQs

How will CM affect a child’s daily life?

Most children with CM and AM attend school as normal. They even play outside and participate in many activities. However, some children may tire more easily, experience short breath, or need to avoid strenuous and competitive sports. With the proper treatment and lifestyle adjustments, children lead active and fulfilling lives.

What warning signs of CM should a parent look out for?

• Unexplained fatigue
• Shortness of breath or fast breathing
• Swelling in the legs, abdomen, or around the eyes
• Palpitations (fast or irregular heartbeats)
• Chest pain
• Poor growth in infants

Contact your healthcare provider if any of these occur.

Are AMs always an indication of heart disease?

No. Many AMs are harmless and do not require treatment. However, those that cause very fast, very slow or irregular heartbeats may indicate a more significant issue. A healthcare provider will determine which AMs need treatment.

How does CM affect adult life and career choices?

Many children transition into healthy adults, but some may continue to need medications, regular follow-ups, or procedures. Career choices may be influenced if a job involves extreme physical exertion or substantial risk of sudden cardiac events. With proper management and lifestyle planning, most children end up living productive adult lives.