FAQ

Many people who experience sudden cardiac arrest have no prior diagnosis — which is part of what makes it so devastating. However, there are warning signs that should always be taken seriously and investigated:

Unexplained fainting, particularly during or immediately after exercise, or in response to a sudden loud noise or fright.

Unexplained seizures that your doctor has not been able to explain with a neurological cause.

Palpitations — a racing, fluttering, or irregular heartbeat — that come on during physical activity.

Significant breathlessness or dizziness during exercise that seems disproportionate to the effort.

A family history of young sudden death — anyone in your family who died suddenly and unexpectedly under the age of 40, or who was found to have an inherited heart condition.

A known inherited cardiac condition in a close relative, even if you have no symptoms yourself.

If any of these apply to you or a family member, do not wait. Speak to your GP about a referral to a cardiologist, or ask specifically about a referral to an inherited cardiac conditions (ICC) clinic. Many inherited heart conditions are highly treatable when identified early.

Category: Inherited Conditions

Yes. Sudden cardiac arrest can affect children and young people, and it is more common than most people realise. It usually happens because of an inherited heart condition that has not been identified — often because the child had no obvious symptoms beforehand.

Conditions that can cause cardiac arrest in children and teenagers include:

CPVT (Catecholaminergic Polymorphic Ventricular Tachycardia) — triggered by exercise or sudden fright, often presenting in the first two decades of life.

Long QT Syndrome — which can cause dangerous arrhythmias during exercise, swimming, or in response to sudden loud noise, and sometimes during sleep.

Hypertrophic Cardiomyopathy (HCM) — the most common inherited heart muscle condition, which can affect young people and is associated with exercise-triggered events.

ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy) — a genetic condition that can affect young adults, particularly those who exercise regularly.

This is one reason why cardiac screening of young athletes, and the families of anyone who has experienced a young sudden death or been diagnosed with an inherited cardiac condition, is so important. If a child in your family has been diagnosed with an inherited heart condition, all first-degree relatives — including siblings — should be assessed by a specialist.

Category: Cardiac Arrest

An ICD (Implantable Cardioverter Defibrillator) is a small device implanted under the skin, typically near the collarbone. It monitors your heart rhythm continuously and, if it detects a life-threatening arrhythmia, delivers a shock or pacing therapy to restore a normal rhythm. It works automatically — you do not need to do anything for it to act.

Not everyone with a heart condition needs an ICD. Whether one is appropriate depends on your specific diagnosis, your individual risk of a dangerous arrhythmia, and a detailed assessment by a specialist cardiologist.

ICDs are commonly considered for people who have already survived a cardiac arrest, and for some people assessed as being at high risk due to conditions including Hypertrophic Cardiomyopathy (HCM), Brugada Syndrome, CPVT, Long QT Syndrome, ARVC, and Dilated Cardiomyopathy. The decision is always individual — having one of these conditions does not automatically mean you need an ICD.

If you have been told you may need an ICD and want to understand the decision better, ask your specialist to walk through the reasons and what the alternatives are.

Category: Implantable Devices

Having an inherited heart condition does not mean you will experience a cardiac arrest. It means you need the right specialist care, regular monitoring, and an informed conversation with your cardiologist about your personal risk profile.

Many people live long, full lives with conditions such as Hypertrophic Cardiomyopathy (HCM), Long QT Syndrome, Brugada Syndrome, CPVT, ARVC, and Dilated Cardiomyopathy — particularly when they are well managed. Understanding your specific triggers, adhering to any activity guidance, and taking prescribed medication consistently all make a significant difference.

Key steps if you have an inherited heart condition:

Know your triggers. Some conditions are provoked by exercise; others by sleep, sudden noise, or fever. Ask your cardiologist specifically what yours are.

Ask about treatment options. Medication, an ICD, catheter ablation, or a combination may all be relevant depending on your condition and risk.

Ensure your family is screened. Many inherited cardiac conditions can pass silently through families. First-degree relatives should be assessed even if they have no symptoms.

If you feel your condition is not being adequately monitored, ask your GP for a referral to an inherited cardiac conditions (ICC) clinic.

Category: Cardiac Arrest

Long QT Syndrome (LQTS) is an inherited condition affecting the heart’s electrical system. It causes a prolonged QT interval on an ECG — a measurement of the time it takes the heart’s lower chambers to recharge between beats. When this interval is too long, the heart is vulnerable to a dangerous arrhythmia called Torsades de Pointes, which can degenerate into ventricular fibrillation and cause sudden cardiac arrest.

In children, LQTS most commonly presents through symptoms triggered by exercise, sudden loud noises, or emotional stress — all of which cause a surge of adrenaline that the heart’s electrical system cannot manage safely. Fainting during sport or in response to a shock is a warning sign that should always be investigated. In some cases, the first presentation is a cardiac arrest.

There are several genetic subtypes of LQTS, and the specific subtype influences both the triggers to avoid and the treatment approach. Beta-blockers are the mainstay of treatment for most types and are very effective at reducing risk when taken consistently. Some patients also require an ICD, particularly those who have already had a cardiac arrest or who have not responded adequately to medication.

Because LQTS is inherited, first-degree relatives — parents, siblings, and children of the affected person — should all be offered cardiac screening, including an ECG. Family screening is arranged through an inherited cardiac conditions (ICC) service. Ask your child’s cardiologist for a referral if this has not already been arranged.

Some medications can dangerously prolong the QT interval and must be avoided. A list of drugs to avoid is maintained at CredibleMeds.org. Always inform any prescribing clinician, dentist, or anaesthetist of the diagnosis before any medication is prescribed or procedure carried out.

Category: Children

CPVT — Catecholaminergic Polymorphic Ventricular Tachycardia — is a rare inherited arrhythmia syndrome in which the heart is structurally normal but specific triggers, particularly physical exertion or emotional stress, can provoke dangerous ventricular arrhythmias. These can cause palpitations, blackouts, or sudden cardiac arrest.

CPVT is caused by mutations affecting calcium regulation within heart muscle cells, most commonly in the RYR2 gene. It typically presents in childhood or adolescence and can cause sudden cardiac arrest in young people who appear otherwise completely healthy. A standard resting ECG may be normal; an exercise stress test often reveals the characteristic bidirectional ventricular tachycardia.

Treatment includes beta-blockers to reduce the risk of arrhythmias triggered by adrenaline, strict avoidance of competitive and high-intensity exercise, and in many cases ICD implantation. Some patients are also treated with flecainide.

Because CPVT is inherited, family screening is essential following a diagnosis. First-degree relatives should be assessed with an exercise stress test as well as a resting ECG and echocardiogram, as the resting ECG may appear entirely normal even in affected individuals.

Category: Implantable Devices

Hypertrophic Cardiomyopathy (HCM) is the most common inherited heart muscle condition. In HCM, the walls of the heart — most often the left ventricle — become abnormally thickened (hypertrophied), which can obstruct blood flow, cause the heart to pump less efficiently, and create dangerous arrhythmias.

HCM affects approximately 1 in 500 people and is a leading cause of sudden cardiac death in young people, including young athletes. Many people with HCM have no symptoms at all; others experience breathlessness, chest pain, palpitations, or blackouts. In some cases, the first sign of HCM is a cardiac arrest.

HCM is caused by mutations in genes that encode the proteins of the heart muscle, most commonly MYH7 and MYBPC3. It is inherited in an autosomal dominant pattern, meaning each first-degree relative of someone with HCM has a 50% chance of carrying the same gene variant.

Treatment depends on symptoms and risk profile and may include medication (beta-blockers, calcium channel blockers), a procedure called septal reduction therapy (to reduce obstruction), and ICD implantation for those at high risk of sudden cardiac arrest.

Family screening — with ECG, echocardiogram, and genetic testing — is strongly recommended for all first-degree relatives.

Category: Inherited Conditions

Brugada Syndrome is an inherited heart condition in which the heart’s electrical system malfunctions despite the heart having a normal structure. It is caused by mutations affecting sodium channels in heart cells — most commonly in the SCN5A gene — and produces a characteristic pattern on an ECG. People with Brugada Syndrome are at risk of dangerous ventricular arrhythmias (abnormal heart rhythms), which can cause sudden cardiac arrest, most often at rest or during sleep.

Brugada Syndrome is more common in men and in people of South-East Asian descent. It may be diagnosed after an unexplained cardiac arrest, after an abnormal ECG is found incidentally, or through family screening following a diagnosis in a relative.

The main treatment for those considered at high risk is an ICD (implantable cardioverter defibrillator), which can detect and terminate life-threatening arrhythmias. Certain medications and substances — including some antidepressants, sodium channel-blocking drugs, and large amounts of alcohol — can trigger arrhythmias in Brugada Syndrome and should be discussed with your cardiologist.

Because Brugada Syndrome is inherited, first-degree relatives (parents, siblings, and children) of anyone diagnosed should be offered cardiac screening.

Category: Implantable Devices

If your cardiac arrest was caused by or is suspected to be related to an inherited heart condition, it is important that your first-degree relatives — parents, siblings, and children — are offered cardiac screening. This is recommended regardless of whether they have symptoms, as many inherited cardiac conditions produce no warning signs until a serious arrhythmia occurs.

You do not need to wait for your relatives to develop symptoms before seeking assessment. Proactively identifying a condition in a family member — before an event occurs — could save their life.

In the UK, inherited cardiac conditions are managed by specialist cardiac genetics or inherited cardiac conditions (ICC) services, often based at regional cardiac centres. Your cardiologist or electrophysiologist should be able to refer you and your relatives to the appropriate service. The process typically begins with a detailed family history, followed by investigations such as ECG, echocardiogram, exercise testing, and in some cases genetic blood testing.

The charity Cardiac Risk in the Young (CRY) and the British Heart Foundation also provide information and support for families affected by inherited cardiac conditions.

Category: Cardiac Arrest

It depends on the cause. Cardiac arrest itself is not directly inherited — but many of the conditions that cause it can run in families.

If your cardiac arrest was caused by an inherited condition such as Hypertrophic Cardiomyopathy (HCM), Long QT Syndrome, Brugada Syndrome, or Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), there is a significant chance that first-degree relatives (parents, siblings, and children) may carry the same genetic variant and be at increased risk themselves. In some conditions, the risk to first-degree relatives is as high as 50%.

If your cardiac arrest was caused by coronary artery disease (blocked arteries), there is an increased familial risk of heart disease, though this is due to a combination of genetic and lifestyle factors rather than a single gene.

If no cause was identified (idiopathic ventricular fibrillation), inherited channelopathies are sometimes present without a detectable structural abnormality, and family screening may still be recommended.

Your cardiologist or electrophysiologist should discuss family screening with you following your cardiac arrest. If they have not, ask them directly. The process typically involves first-degree relatives having an ECG, echocardiogram, and in some cases genetic testing.

Category: Cardiac Arrest

While there are a number of possible causes, three are particularly common in the UK. The first is Hypertrophic Cardiomyopathy (HCM), a genetic heart muscle condition in which the walls of the heart’s left ventricle become abnormally thickened. This can obstruct blood flow from the heart, causing loss of consciousness and a dangerous arrhythmia leading to cardiac arrest. The second is Long QT Syndrome, an often-unrecognised inherited condition affecting the heart’s electrical system that can predispose young people to life-threatening arrhythmias. Episodes are most commonly triggered by physical exertion or emotional stress. The third is commotio cordis, an electrical disturbance triggered by a sharp blow to the chest at a critical moment in the heart’s cycle. It can occur in contact sports such as football, cricket, rugby, and martial arts, as well as any situation involving a forceful blow to the chest.

Category: Children

Not automatically, but it depends on why you have an ICD. If your device was implanted following a cardiac arrest or arrhythmia caused by an inherited condition such as HCM, Long QT Syndrome, Brugada Syndrome, CPVT, or ARVC, then your first-degree relatives should be offered cardiac screening. These conditions can run in families and may be present in relatives who have no symptoms at all.

Family screening is arranged through an inherited cardiac conditions (ICC) clinic. Your own cardiologist can make a referral, or your relatives can ask their GP to refer them. Screening typically includes an ECG and echocardiogram, and may include an exercise stress test or genetic testing depending on the condition involved.

A positive finding in a family member does not automatically mean they will need an ICD. Treatment depends on the condition, the individual’s risk profile, and their clinical presentation. Some family members will need no treatment at all; others may be started on medication or monitored regularly.

If your ICD was implanted for a reason unrelated to an inherited condition, such as heart failure following a heart attack, routine family screening is not usually indicated, though your cardiologist will advise.

Category: Implantable Devices