Many individuals with HCM experience no symptoms. For those who have heart failure, symptoms may include:

Newborns and babies

• Difficulty feeding or poor growth
• Excessive sweating during feeds or activity

Older children and adults

• Shortness of breath and fatigue
• Feeling dizzy or light-headed
• Fainting or passing out (syncope)
• Feeling abnormal heart beats (palpitations)
• Chest pain

While some children who have HCM experience no symptoms, they may still be at risk for complications of the condition. The most serious is sudden cardiac arrest, which is a loss of heart function caused by a dangerously fast heart rhythm called ventricular tachycardia. Without immediate emergency treatment, such as CPR and defibrillation, cardiac arrest may lead to death.

Risk for sudden cardiac arrest is low for most people. However, HCM is the most common cause of sudden cardiac death in people under the age of 30.

A family history of HCM is present in around 40 to 70 percent of cases. Most commonly, the genetic cause results in a condition that runs in a family and affects only the heart. It is possible that parents, siblings and even aunts / uncles or cousins of an individual with HCM may also have this heart muscle condition.

Other causes of HCM include:

• Genetic syndromes, metabolic & mitochondrial disorders
• Prolonged, untreated or poorly controlled high blood pressure
• Athletic endurance training
• Idiopathic – cause is unknown

The following are possible methods of diagnosing HCM:

• Medical history of heart failure symptoms, rhythm problems and instances of passing out
• Physical exam to assess skeletal muscle strength and identify signs of possible cardiac problems
• Echocardiogram – noninvasive ultrasound test that uses sound waves to produce images of the heart
• Blood tests
• Electrocardiogram (EKG or ECG) - quick, painless and noninvasive test in which electrodes are taped to the chest to record the heart’s electrical signals
• Electrophysiologic (EP) testing – physicians insert catheters into the heart to record electrical activity and determine the cause of the rhythm disturbance
• Cardiac MRI (magnetic resonance imaging) - noninvasive medical test that uses magnetic field and radio wave energy to make detailed pictures of the heart’s internal structure
• Exercise stress echo test which involves exercising on a treadmill or stationary cycle under close monitoring
• Genetic Testing — to determine whether or not a genetic mutation is present
• Family history of cardiomyopathy, rhythm problems, sudden cardiac or unexplained death, cardiac surgery or presence of other cardiac disease in relatives.

Echocardiogram is the most common test used to diagnose HCM, as the expansion of the ventricle and overall squeeze of the heart can be measured.

It is recommended that all family members (parents, siblings, children, grandchildren, uncle, aunt, nephew, niece) be evaluated carefully for this form of cardiomyopathy, even if they have no symptoms.

A genetic counselor and / or geneticist can assess the family history and provide information about the chances of a genetic predisposition to cardiomyopathy.

Please read more about genetic testing for cardiomyopathy.

Treatment of HCM is unique for every child and is based on a number of features including:

• Outflow tract obstruction, when blood isn’t able to leave the left ventricle because of the thickened muscle
• Problems with the function of the heart, trouble squeezing / pumping blood
• Presence of symptoms
• Age & activity level of the child
• Presence of abnormal heart rhythms
• Family history

Treatment is aimed at minimizing or preventing symptoms and reducing the risk of complications such as heart failure and sudden cardiac arrest.

The following may be methods of treatment for your child’s HCM:

• Medications such as beta-blockers & calcium channel blockers to relax the heart muscle
• Medications to control the heart rate or decrease the occurrence of irregular heartbeats
• Lifestyle changes – reducing or eliminating endurance sports
• Surgical procedure(s) to reduce muscle wall thickness

Each individual child’s risk for more serious problems such as sudden cardiac arrest will be assessed by the doctor, who may recommend an implantable cardioverter-defibrillator (ICD), an automated device placed under the skin that tracks the heart rate and sends electrical signals to the heart if it detects abnormalities. This will reduce the chance of a sudden cardiac death.