17183 Long Q T Syndrome Lqts

Overview

Long QT syndrome (LQTS) is a rare heart rhythm problem. The heart's electrical system controls when it beats. In LQTS, the heart takes longer than usual to recharge between beats. This can sometimes cause a very fast, dangerous heart rhythm. The name comes from a portion of an electrocardiogram (ECG) – a test that records the heart's electricity. The QT interval is measured in milliseconds.

No, LQTS is not common. Around 1 in 2,000 people may have it, but many do not know.

It can affect anyone at any age. Symptoms often start in childhood or young adulthood. Some types are more common in males or females, and medicine-related forms are more likely in older adults.

Symptoms

Common symptoms

• Fainting (syncope) – often without warning, sometimes during exercise, emotion, or sudden noise.
• Dizziness or light-headedness.
• Palpitations – feeling like your heart is skipping, fluttering, or beating too fast.
• Seizures – a very fast rhythm can briefly cut off blood flow to the brain.
• No symptoms at all – some people only find out after a routine ECG or because of a family member.

Symptoms in children

• Fainting or near-fainting during physical activity, especially swimming.
• Fainting when scared, startled, or upset.
• Unexplained fainting that happens during or after exercise.
• Seizure-like episodes caused by a very fast heart rhythm.

Symptoms in older adults

• Dizziness or fainting episodes, especially after starting a new medicine.
• Palpitations or irregular heartbeat.
• Unexplained falls or confusion that may actually be caused by brief fainting.

Causes

Main causes

• Genetic changes (mutations) passed down in families – this is the most common cause.
• Certain medicines can prolong the QT interval, including some antibiotics, heart medicines, and medicines for depression or allergic reactions.
• Low levels of potassium, calcium, or magnesium in the blood.
• Some heart conditions, such as heart attacks or heart failure, can cause an acquired form.

Risk factors

• A family history of long QT syndrome or unexplained sudden death at a young age.
• Taking medicines known to affect the heart's electrical system.
• Being female, as some types of LQTS are more common in women.
• Having hearing loss and a genetic syndrome that affects the heart (rare).

When to see a doctor

See a doctor urgently if:

• If you faint or have a seizure, get medical help right away – especially if it happens during exercise or emotion.
• If you have palpitations with dizziness, chest pain, or fainting – seek same-day emergency care.

Book a routine appointment if:

• If you have a family member diagnosed with LQTS, ask your doctor about getting an ECG and genetic counselling.
• If you have repeated dizzy spells or unexplained fainting, talk to your GP.
• Before starting any new medicine, tell your doctor and pharmacist about your LQTS.

Diagnosis

LQTS is diagnosed by a specialist doctor, usually a cardiologist. They will use an ECG to measure the QT interval and may use other tests to confirm the diagnosis. If you have symptoms or a family member with LQTS, they will also check your medical history and may recommend genetic testing.

Tests that may be done

• Electrocardiogram (ECG) – a quick, painless test that records the heart's electrical signals.
• Holter monitor – a portable ECG worn for 24–48 hours to capture your heart's activity during daily life.
• Exercise stress test – ECG recorded while walking on a treadmill to see the heart's response to exercise.
• Genetic blood test – looks for known changes linked to LQTS.
• Family screening – close relatives may also be offered testing.

What to expect at your appointment

You may be referred to a heart rhythm clinic. During the first visit, the specialist will go through your symptoms, family history, and test results. They may ask you to stop certain medicines temporarily before the ECG. You will usually get clear recommendations about lifestyle changes, medicines, and follow-up appointments.

Treatment

Treatment for LQTS focuses on preventing dangerous heart rhythms, not curing the genetic condition. Your doctor will tailor your care to your individual risk, which depends on your type of LQTS, your symptoms, and your family history. Most people need to make lifestyle changes and take daily medicines. Some may need a small device implanted under the skin to correct dangerous rhythms.

Self-care at home

• Avoid known triggers – such as getting startled, sudden sharp noises, intense exercise, or swimming alone.
• Tell every doctor, dentist, or pharmacist about your LQTS before you are prescribed any medicine.
• Wear a medical alert bracelet or necklace that says 'Long QT Syndrome'.
• Stay well hydrated and avoid dehydration, especially in hot weather.
• Avoid recreational drugs and limit alcohol and caffeine if they bother your heart.

Medical treatments

Medicines called beta-blockers are the most common treatment for LQTS. They work by slowing the heart rate and making it easier for the heart to recharge between beats. In some people, other rhythm-controlling medicines may be used. Your doctor will decide which medicine is right for you and will start it at a low dose and adjust it as needed. Never stop or change your medicine without your doctor's advice.

When is surgery considered?

If you are at high risk of sudden cardiac arrest, a doctor may recommend a small device called an implantable cardioverter-defibrillator (ICD). It is placed under the skin in your chest and checks your heartbeat. If a very fast rhythm starts, it gives a small electric shock to restore a normal rhythm. Sometimes a surgical procedure to interrupt nerve signals to the heart can also be considered.

Living with this condition

Living with LQTS requires awareness rather than limitation. Many everyday activities are fine, but you should learn to listen to your body. Carry a phone, avoid strenuous activities alone, and make sure people close to you know what to do in an emergency. With the right precautions, you can study, work, and enjoy a full life.

Lifestyle tips

• Have regular check-ups with your heart specialist.
• Learn how to take your pulse and recognise warning signs.
• Make sure your family knows how to call for emergency help.
• Avoid sudden loud noises like alarm clocks that startle you – use gentle ringtones or lights.
• Plan exercise with your doctor – some people with LQTS can exercise safely, but it must be individualised.

Diet and exercise

Eat a balanced diet to keep your electrolyte levels healthy. Foods such as bananas, leafy greens, and nuts provide potassium and magnesium, but you do not need special supplements unless your doctor recommends them. In terms of exercise, your cardiologist will tell you what is safe for you. In general, avoid extreme exertion, sudden sprints, and swimming alone. Low-to-moderate activities like walking, cycling, or yoga are often encouraged.

Mental health and emotional wellbeing

Being diagnosed with LQTS can feel frightening. You may worry about when a symptom might happen, or feel anxious about exercise and daily activities. This is normal. It can help to talk to a counsellor or psychologist, and to keep an open dialogue with your doctor. Remember that a diagnosis gives you information – and information helps you take control.

Prevention

You can't prevent inherited LQTS, because it is in your genes. But you can prevent dangerous episodes by discovering the condition, avoiding triggers, and following your treatment plan. This is why it's so important to talk to a doctor if you have a family history or symptoms.

Vaccines

There is no vaccine for LQTS because it is not an infection. Standard immunisations are safe for most people with LQTS, but always tell your clinician about your condition before any vaccination.

Screening programmes

If you have LQTS, your close relatives should be offered an ECG and genetic counselling to check if they also have it. Early detection means they can take precautions before a dangerous rhythm ever happens.

Complications

If left untreated

• Fainting episodes that happen during activities such as swimming or driving, which can lead to injury.
• A very fast, chaotic heart rhythm (ventricular arrhythmia) that can cause sudden cardiac arrest.
• Sudden death, although this is rare when LQTS is properly managed.

Long-term outlook

The outlook for most people with LQTS is good. With the right treatment and lifestyle adjustments, the risk of a dangerous heart rhythm is very low, and most people lead full, active lives. The key is to work closely with your heart specialist and follow their advice. If you ever have a warning symptom, get help immediately – do not ignore it.

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