Long QT Syndrome

What is Long QT syndrome?

Long QT Syndrome is a heart rhythm disorder that can lead to sudden, uncontrollable, and dangerous arrhythmias.

Essentially it causes the heart to take longer to return to its resting state following the electrical signal that triggers each heartbeat. When that happens, it can put the heart at risk of going into life-threatening arrhythmia.

It can be genetic – caused by a gene mutation – or triggered by external factors such as side effects to certain medicines and mineral imbalances.

Long QT is a rare syndrome that is estimated to affect between one in 2000- 7000 people.

What are the symptoms of Long QT?

Many people don’t have any symptoms, and often only find out when they have an electrocardiogram (or ‘ECG’).

For those that do have symptoms they can include:

• Palpitations which can feel like your heart is beating faster, fluttering, or skipping a beat.
• Fainting or feeling like you are going to faint.
• Seizures
• Sudden cardiac arrest – This is when the heart suddenly stops pumping blood and ceases to beat. It’s estimated that around one in 10 people who have Long QT syndrome will experience cardiac arrest as a first symptom. Ninety percent of people who have a cardiac arrest outside of hospital will not survive.

How do you diagnose Long QT syndrome?

If you experience any of the above symptoms talk to your GP who can refer you to a specialist who can make a formal diagnosis by running a series of tests.

• They can include electrocardiograms or ECGs which record the electrical activity of your heart and can detect any unusual activity consistent with Long QT.
• An exercise stress test – this is like an ECG but conducted on a treadmill. Research has shown that it’s an important tool in diagnosing Long QT.
• Heart monitoring – your specialist may give you a small device you can wear at home that will record your heart’s electrical activity over one or two days.
• Genetic testing – current genetic tests can reveal if you have a genetic mutation associated with Long QT.

How is Long QT treated?

Treatment will vary depending on whether your Long QT is inherited and caused by a genetic mutation or triggered by a mineral imbalance or reaction to certain medications.

For those with inherited Long QT treatment can include:

• Medication – the most common form of medication to treat Long QT are Beta-Blockers which are commonly prescribed to manage abnormal heart rhythms. In Long QT patients They work by shortening the time it takes for the heart to return to its normal state
• Pacemaker – if your specialist believes your Long QT is very severe and cannot be managed by medications alone or deem you at risk of having a sudden cardiac arrest, or suffering another arrest, you will likely be recommended to have a pacemaker inserted in your chest. This will help control your heartbeat.
• Implantable cardioverter-defibrillator – as well as a pacemaker patients may also have this device inserted close to their heart. This monitors the heart and in case of life-threatening arrhythmias, it can create an electrical shock and prevent sudden cardiac arrest.

Non inherited Long QT

For those with Long QT caused by a reaction to medication, your specialist will work with you to analyse which drug is triggering the reaction. In some cases, simply stopping taking the drug and using a safer alternative may prevent any further Long QT symptoms. Other patients may require extra treatment.

Around 100 drugs have been associated with causing Long QT – many of them common including anti-depressants, antibiotics, and diuretics.

If your Long QT is associated with a mineral imbalance such as being deficient in potassium or magnesium, the first step is to identify and fix the imbalance. Patients may require no extra treatment.

What is the long-term outlook for people with Long QT?

If untreated and symptomatic up to 20 percent of people with Long QT may die within a year. But once diagnosed and treated, the prognosis for people with Long QT is good with the risk of suffering cardiac arrest dropping to less than 1% over 20 years.