Inherited Electrical Disease
Inherited Arrhythmia Syndromes
Inherited arrhythmia syndromes are conditions in which a tendency to abnormal heart rhythms is passed through families, often in hearts that look structurally normal. Assessment is individual and often involves the whole family.
On this page
Overview
What Are Inherited Arrhythmia Syndromes?
Inherited arrhythmia syndromes are a group of conditions caused by differences in genes that affect the heart’s electrical system. They can make abnormal rhythms more likely in some people. Many people with these conditions have no symptoms and live normal lives, while others are at risk of serious rhythm problems.
This page gives an overview of the main groups. Each condition is different, and the information here does not replace a personal assessment.
Conceptual illustration of the heart’s electrical system
Two kinds of heart conditions
Electrical Disorders and Heart Structure
Electrical
Primary electrical conditions
The heart muscle usually looks normal on imaging. The problem lies in how electrical signals are generated or carried.
Many inherited arrhythmia syndromes belong to this group.
Structural
Conditions of heart muscle
The heart muscle or valves are affected, and the rhythm problem develops as a result.
These are assessed and managed differently.
Why it matters
Family History
A family history of unexplained fainting, seizures, serious rhythm problems or sudden death at a young age may suggest an inherited condition. It does not prove one. The doctor will ask about relatives and may recommend tests for you and sometimes for family members.
Having a relative with one of these conditions does not mean that you will have it. Testing helps to clarify the situation.
Overview
Brugada Syndrome
Brugada syndrome is an inherited condition associated with a characteristic ECG pattern and, in some people, a risk of dangerous rhythms from the lower chambers of the heart. The ECG pattern can vary over time and may only appear under certain conditions.
Many people with the pattern have no symptoms. Assessment aims to clarify the diagnosis and the level of individual risk.
Overview
Long QT Syndrome
In long QT syndrome, the heart’s electrical system takes longer than usual to reset between beats. This is seen as a prolonged QT interval on the ECG. It can lead to a specific fast rhythm that may cause fainting or, rarely, more serious events. Some medicines can also lengthen the QT interval, so your doctor will ask about all medicines you take.
Overview
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)
CPVT is an inherited condition in which physical or emotional stress can trigger dangerous rhythms from the lower chambers. The resting ECG is often normal, so the diagnosis may need exercise testing, monitoring or genetic testing.
Long QT syndrome
Long QT Syndrome: Triggers, Evaluation and Management
Types and causes
Long QT may be inherited, with several genetic subtypes that differ in their typical triggers, or acquired through certain medicines, low potassium or magnesium and other conditions. Telling these apart matters because management differs.
Triggers
Depending on the subtype, triggers can include exertion, sudden emotional stress or sudden loud noises, and rest or sleep. Medicines that prolong the QT interval and electrolyte disturbances can also provoke rhythm problems. Advice on medicines to avoid is individual.
Family history
Unexplained fainting, seizures or sudden death at a young age in relatives may point to long QT. Relatives are offered ECG and, when appropriate, genetic assessment.
ECG and genetic evaluation
The QT interval is measured on repeated ECGs, sometimes with exercise testing or longer monitoring, because it can vary. Genetic testing can identify the subtype and help test relatives, but a negative result does not always exclude the condition. See Electrocardiography.
Risk assessment
Takes into account symptoms such as fainting, the length of the QT interval, the genetic subtype, family history and earlier events. There is no single number that fits everyone.
Treatment considerations
Options are chosen individually. They may include avoiding QT-prolonging medicines, correcting electrolytes, medicines such as beta-blockers in many inherited cases and, in selected patients, procedures or an implantable defibrillator. Exercise and sport advice depends on the subtype and the person.
CPVT
CPVT: Stress-Related Ventricular Arrhythmia
Mechanism
CPVT is usually linked to changes in genes that control calcium handling inside heart cells. The heart often looks structurally normal and the resting ECG is often normal.
Triggers
Physical exertion and strong emotion can provoke irregular ventricular beats and, in some people, a dangerous fast rhythm. Fainting during exercise or stress, often first in childhood or adolescence, may be the first sign.
Diagnosis
Exercise testing can reproduce the characteristic pattern of ventricular beats and is combined with rhythm monitoring and genetic testing. See Exercise ECG.
Family evaluation
Relatives are usually offered assessment, including exercise testing and sometimes genetic testing, because carriers can have no symptoms.
Management considerations
Management usually involves medicines that reduce the effect of adrenaline on the heart (see Antiarrhythmic Medication), individual advice on exertion and stress and, in selected patients, other procedures or an implantable defibrillator.
Exercise advice differs between conditions and subtypes and may change over time. Decisions on activity and medicines are made with a specialist in inherited rhythm conditions.
Other conditions
Other Inherited Conditions
There are other inherited rhythm conditions, for example short QT syndrome and some inherited conduction disorders. They are less common and are assessed individually.
What people notice
Symptoms
Many people have no symptoms. When symptoms occur, they can include fainting, especially during exercise, emotion or sleep, palpitations, or seizure-like episodes. Any unexplained fainting should be assessed by a doctor.
If someone collapses or loses consciousness, seek emergency help immediately.
Diagnosis
The Role of the ECG
The ECG is the first test. It can show patterns that suggest a specific condition, and repeat or specialised recordings may be needed. Ambulatory monitoring can show rhythm problems that come and go.
Diagnosis
Genetic Assessment
Genetic testing may be offered in selected situations. It can help to confirm a diagnosis and to test relatives. A result is not always clear: a person can carry a variation without developing the condition, and sometimes no cause is found. Counselling is usually offered before and after testing.
Individual assessment
Risk Assessment
The level of risk differs widely between people and between conditions. Your doctor considers symptoms, ECG findings, family history, test results and the specific diagnosis. There is no single number that fits everyone, and the plan is decided together with the patient.
High-level overview
Treatment Strategies
Treatment depends on the condition and the individual risk. Options may include:
Lifestyle advice
Guidance on triggers, medicines to avoid, and activity.
Medicines
Selected medicines for some conditions, prescribed by your doctor.
In selected patients, an implantable cardioverter-defibrillator (ICD) may be considered.
Other procedures
Used only in particular situations after specialist assessment.
Relatives
Family Screening
When a condition is found, close relatives may be offered ECG, other tests and sometimes genetic testing. Screening can identify relatives who would benefit from follow-up, and reassure those who are not affected.
Long term
Follow-up
People with an inherited arrhythmia syndrome usually have regular follow-up. Visits review symptoms, rhythm recordings, treatment and any changes in the family. Follow-up does not mean that something is wrong; it helps to keep the plan up to date.
Questions
Frequently Asked Questions
What is an inherited arrhythmia syndrome?
A condition in which a tendency to abnormal heart rhythms is passed through families, often in a structurally normal heart.
Does a family history mean I have it?
No. It may suggest an inherited condition, and testing helps to clarify the situation.
Can the ECG be normal?
Sometimes. Some conditions show changes only at certain times or under stress, so further tests may be needed.
Do I need genetic testing?
It is offered in selected situations. Your doctor will explain whether it may help.
Will I need a device?
Not everyone does. A device is considered only in selected patients after careful assessment.
Should my relatives be tested?
Often close relatives are offered screening. Your doctor will advise on this.
Can I exercise?
This depends on the condition and the individual. Ask your doctor for advice that fits you.
Is follow-up needed for life?
Usually regular follow-up continues, with the frequency decided individually.