QT Syndrome

Long QT Syndrome Information

Before Diagnosis

What is Long QT Syndrome (LQTS)?

LQTS is a condition caused by a dysfunction in the heart's ion channels, leading to a prolonged electrical activity in the heart (QT interval). This can result in irregular heartbeats and, in rare cases, increase the risk of cardiac arrest and sudden death.

Is Long QT Syndrome inherited or acquired?

LQTS has two types: inherited and acquired. The inherited type is passed down through generations in affected families, with specific triggers increasing the risk of cardiac arrest in those affected. The acquired type results from external factors.

What are the triggers for symptoms in inherited LQTS?

Using medications that interfere with LQTS (listed at the end of the document).
Post-pregnancy and during the postpartum period (in some types of LQTS).
Electrolyte imbalances (low potassium or calcium) during episodes of dehydration or gastroenteritis.
Certain physical activities (depending on intensity and competitiveness).
Sudden auditory stimuli.

What external factors cause acquired LQTS?

Severe electrolyte imbalances, particularly low potassium or calcium, often seen in individuals with eating disorders (such as anorexia nervosa or bulimia).
Using medications that interfere with LQTS (listed at the end of the document).

What are the symptoms of Long QT Syndrome?

The majority of individuals with LQTS are asymptomatic and discover it incidentally during an electrocardiogram (ECG) performed for unrelated reasons.
Heart palpitations, seizures, or fainting, especially during physical exertion.
In very rare cases, the first symptom of LQTS may be cardiac arrest.
LQTS does not cause chest pain or shortness of breath.

Does Long QT Syndrome cause sudden death?

LQTS can be a cause of sudden death. However, the percentage of individuals with LQTS who are at high risk for sudden death is very small.

How is Long QT Syndrome detected?

After symptoms appear and an ECG shows prolonged QT waves, confirming the diagnosis. Some cases are detected during ECGs conducted for other reasons (e.g., employment screenings, pre-surgical evaluations, or routine check-ups). Family screenings after confirming a diagnosis in a primary case may reveal LQTS in asymptomatic relatives.

How is Long QT Syndrome diagnosed?

Diagnosis is made through an ECG.
If there is a high suspicion of LQTS but the ECG is inconclusive, a stress test may be performed to provoke prolonged QT waves, confirming the condition.
Genetic testing can also diagnose LQTS even in individuals without prior symptoms or ECG abnormalities, especially during family screenings.

When is suspicion of Long QT Syndrome high?

A family history of sudden death under age 50 in first-degree relatives, especially deaths during physical exertion or the postpartum period.
During family screenings of an individual diagnosed with LQTS.
Unexplained cardiac arrest.

What is a stress test for diagnosing Long QT Syndrome?

It’s a test used when LQTS is highly suspected but initial ECG results are negative. Conducted as an outpatient procedure, the test involves exercise on a treadmill to provoke QT wave abnormalities. For individuals unable to exercise, an adrenaline injection is used to simulate physical activity, with continuous ECG monitoring for at least an hour. The test does not require anesthesia or other precautions, except for fasting three hours prior. It is safe, quick, and patients can resume normal activities afterward.

After Diagnosis

What preventive measures should be taken after an LQTS diagnosis?

Avoid medications that trigger LQTS, as they increase the risk of cardiac arrest. These include certain anti-arrhythmics, psychiatric drugs, and antibiotics (list provided at the end).
Avoid sudden auditory triggers (e.g., loud phone alarms) and situations causing abrupt emotional reactions.
For some types of LQTS, consider limiting or avoiding physical exertion, particularly swimming.
Prevent dehydration and electrolyte imbalances during illnesses like gastroenteritis.

What are the complications of Long QT Syndrome?

Most individuals with LQTS live normal lives without complications if they take regular medication and avoid triggers.
A small percentage may experience fainting or seizures, requiring heart rhythm-stabilizing treatments.
Rarely, cardiac arrest occurs, which may necessitate an implantable defibrillator.

How is Long QT Syndrome treated?

Starting beta-blocker therapy to regulate heart rhythms.
Avoiding triggers through preventive measures mentioned above.

Do all LQTS patients need an implantable defibrillator?

No, only patients who experience cardiac arrest or fainting due to heart rhythm disturbances despite taking beta-blockers may require a defibrillator.

Do I need genetic testing after an LQTS diagnosis?

Yes, genetic testing is recommended, as certain genetic mutations are associated with LQTS. If confirmed, family members can also be tested for the same mutations.

Do my family members need screening for Long QT Syndrome?

Yes, first-degree relatives (parents, siblings, and children) should undergo heart and genetic testing if a mutation is found in the diagnosed patient.

Can I become pregnant after an LQTS diagnosis?

Yes, but it requires consultation with a cardiologist specializing in electrophysiology to ensure appropriate treatment and avoid medications that could trigger symptoms.

Can I undergo surgery (including dental procedures) after an LQTS diagnosis?

Surgery does not increase complications in LQTS patients, but care must be taken with certain anesthetics. Inform your doctor of the diagnosis so they can select appropriate medications. A medical report with preventive measures will be provided for other specialists.