Long QT syndrome

Also called Inherited heart rhythm conditions, Brugada syndrome, Wolff-Parkinson-White syndrome

Inherited electrical faults that can cause sudden death in young people. A fainting episode during exercise or a startle is the warning nobody should dismiss.

What it is

A group of inherited conditions affecting the heart's electrical system, in hearts that are structurally normal.

**Long QT syndrome** delays electrical recovery and can trigger a dangerous rhythm, typically during exercise, emotion, a sudden loud noise, or during sleep depending on the type. **Brugada syndrome** causes dangerous rhythms typically at rest, during sleep or with fever. **Wolff-Parkinson-White syndrome** involves an extra electrical pathway, causing fast rhythms and, rarely, sudden death; it is curable by ablation.

Together they are an important cause of sudden cardiac death in young people, and they run in families, usually with a one in two chance for each child.

**Fainting during exercise, during emotion or in response to a sudden noise is the warning sign that must never be dismissed.** It is frequently attributed to a simple faint, dehydration or anxiety, and sometimes to epilepsy, because a rhythm-related collapse can cause jerking.

A resting ECG detects many cases and is the first step. It is cheap and quick.

A large number of medicines prolong the QT interval, and people with long QT must check every new drug, including some antibiotics, antihistamines, antidepressants, antipsychotics and anti-sickness drugs.

For Brugada, fever provokes dangerous rhythms, so treating a temperature promptly is genuine medical advice rather than comfort.

Signs you might notice

Fainting or near-fainting, particularly during exercise, with emotion, on being startled by a loud noise such as an alarm clock, or from sleep.

Palpitations, or a racing heart.

Seizure-like activity during a collapse, which can lead to a wrong diagnosis of epilepsy.

Often nothing at all until a first event.

A family history of sudden unexplained death under 40, unexplained drowning, or an unexplained single-vehicle crash.

999: collapse with no pulse. Start CPR and send for a defibrillator.

Urgent assessment: any faint during exercise or in response to a startle, palpitations with collapse, or a family history of sudden young death, even with no symptoms.

How it can affect day-to-day life

A diagnosis reaches the whole family at once, and telling relatives is a burden that lands on the person diagnosed. Cascade screening of first-degree relatives is standard and should be arranged rather than left to chance.

Exercise restriction varies by condition and by individual risk, and blanket bans are outdated. Get it specified in writing, particularly for children and for school.

The medicines list is the daily discipline. A card or app listing QT-prolonging drugs, shown at every prescription and every pharmacy, prevents avoidable harm.

For Brugada, keeping paracetamol at home and treating fever early is a specific instruction, not general advice.

Implantable defibrillators prevent sudden death and bring their own anxiety, especially after a shock.

Families should learn CPR and know where public defibrillators are. In an inherited condition, the most likely person to save a life is somebody in the household.

Supporting someone well

Never dismiss a faint during exercise, emotion or a startle in a young person. Ask for an ECG.

Ask about family history of sudden unexplained death under 40, and mention drownings and single-vehicle crashes.

Ask for referral to an inherited cardiac conditions service, and for family screening.

Carry the list of medicines to avoid and check every new prescription, including over the counter.

For Brugada, treat fever promptly with paracetamol and seek help if it is high.

Get exercise advice in writing, specific to the condition and the person.

Learn CPR, and find the nearest public defibrillator.

Question a diagnosis of epilepsy where collapses happen on exertion or with a family history of sudden death.

Where to get help

A GP practice for an ECG and referral to an inherited cardiac conditions clinic.

999 for collapse; start CPR immediately.

Arrhythmia Alliance run a helpline and cover inherited rhythm conditions.

British Heart Foundation on 0808 802 1234.