Long QT Syndrome

Overview

Long QT syndrome is a condition in which there is a problem in the regulation of the heartbeat due to a disorder in the heart's electrical system. This syndrome is characterized by the time it takes for the heart to re-electrically charge after each beat (QT interval) being longer than normal. This prolongation can set the stage for the heart to develop dangerous rhythm disorders.

Each time your heart beats, it receives an electrical signal to contract. This signal spreads through your heart and after the contraction is completed, the heart needs to rest for a short time to prepare for the next beat. This rest period is called "repolarization." In long QT syndrome, this rest period is prolonged. A new electrical signal can come before the heart is ready for the next beat, and this can trigger a dangerous rhythm disorder called "torsade de pointes."

Long QT syndrome can be present from birth or can develop later due to certain medications or health problems. The congenital form is genetically inherited and can be seen in families. While it causes no symptoms in some people, in others it can lead to fainting, seizures, or sudden cardiac arrest.

Most people with long QT syndrome can live a normal life with appropriate treatment and lifestyle adjustments. The goal of treatment is to prevent dangerous rhythm disorders and reduce the risk of sudden cardiac arrest. Treatment options may include beta blocker medications, pacemaker, or ICD (implantable cardioverter defibrillator).

Symptoms

In some people with long QT syndrome, no symptoms are seen and the condition is noticed during an electrocardiogram (ECG) taken by chance. In people who show symptoms, findings usually appear during adolescence or young adulthood. The severity of symptoms varies from person to person and tends to occur with certain trigger factors.

The most common symptoms are:

• Fainting (syncope). This is the most common symptom of long QT syndrome. Fainting usually occurs suddenly and unexpectedly. The person suddenly loses consciousness and falls to the ground. They come to on their own within a few seconds or minutes. Fainting often occurs during exercise, after being startled by a sudden sound, or during strong emotional arousal. For example, fainting can occur during a sports competition, when hearing a loud alarm, or when very frightened. These fainting episodes result from the heart temporarily entering a dangerous rhythm disorder and being unable to pump enough blood to the brain.
• Seizure-like movements. When a rhythm disorder similar to cardiac arrest develops during fainting, blood flow to the brain can be completely cut off. In this case, convulsions, jerking in the arms and legs, or stiffening throughout the body may be seen. These movements closely resemble epileptic seizures and can often lead to a mistaken diagnosis of epilepsy. However, this is actually heart-related and requires evaluation by a cardiologist for correct diagnosis.
• Palpitations. Some people may feel their heart beating rapidly, irregularly, or strangely in their chest. This palpitation can last a few seconds and pass on its own. Dizziness, lightheadedness, or dimming of vision may also accompany palpitations. This may be a sign that the heart has briefly entered a dangerous rhythm disorder.
• Sudden cardiac arrest. In rare cases, the first symptom may be sudden cardiac arrest. This is a very serious condition in which the heart cannot pump blood effectively and requires emergency intervention. Fortunately, with appropriate treatment, this risk can be greatly reduced. It is important to screen people with a family history of unexplained sudden death or cardiac arrest at a young age for long QT syndrome.

In long QT syndrome, symptoms usually occur with certain triggers. The most common triggers include exercise (especially swimming), sudden loud noise (alarm clock, phone, siren), strong emotions (fear, anger, excitement), and during sleep. In some long QT syndrome types, symptoms occur more frequently during rest or sleep.

When to See a Doctor

You should definitely see a doctor in the following situations:

• If you have unexplained fainting episodes, especially if these fainting episodes occur during exercise, with a sudden sound, or during emotional stress
• If there is a family history of unexplained sudden death, drowning, or cardiac arrest at a young age (under 50)
• If you were previously diagnosed with epilepsy but your seizures continue despite medication (they may actually be heart-related fainting)
• If you notice unexplained fainting or seizure-like movements in your child
• If a close family member has been diagnosed with long QT syndrome

If the person does not come to during fainting, is not breathing, or does not wake up normally, call emergency services immediately. This may be a sign of sudden cardiac arrest and requires emergency intervention.

Causes

Long QT syndrome occurs as a result of improper functioning of ion channels in heart muscle cells. These ion channels play an important role in the heart's electrical system and allow the heart to restart after each beat. Problems in these channels lead to prolongation of the time it takes for the heart to restart electrically.

The main causes of long QT syndrome are:

Genetic (congenital) causes. The most common form of long QT syndrome results from hereditary genetic mutations. These mutations affect the structure or function of ion channels in heart cells. To date, mutations in 17 different genes have been discovered to lead to long QT syndrome.

The most common types are LQT1, LQT2, and LQT3. These genetic forms are associated with different triggers. For example, in LQT1 type, symptoms usually occur during exercise, while in LQT2 type, sudden sounds or emotional stress can be triggers. In LQT3 type, symptoms are usually seen during rest or sleep.

Genetic long QT syndrome is inherited in an autosomal dominant manner. This means that a person carrying the gene mutation causing the disease has a 50 percent chance of passing this mutation to their children. However, the severity of symptoms may differ in family members carrying the same gene mutation. While some show no symptoms, others may experience serious rhythm disorders.

Medication-related causes. Some medications can prolong the QT interval by affecting the heart's electrical system. These medications can cause problems in people with genetic predisposition, as well as temporarily causing QT prolongation in people who previously had no problems.

Medication groups that can lead to QT prolongation include:

• Some antibiotics (especially macrolide group and fluoroquinolones)
• Some rhythm disorder medications (antiarrhythmics)
• Some antidepressants and antipsychotic medications
• Some antihistamines (allergy medications)
• Some antifungal medications
• Some diuretics
• Some nausea medications

Before using medication, especially if you have a family history of long QT syndrome or unexplained sudden death, you should definitely inform your doctor. Also, over-the-counter medications and herbal supplements can lead to QT prolongation, so it is important to share these with your doctor as well.

Electrolyte imbalances. Decrease or increase in the levels of certain minerals (electrolytes) in the blood can prolong the QT interval. Potassium, magnesium, and calcium imbalances are especially important in this regard.

These imbalances can occur in the following situations:

• Excessive diarrhea or vomiting
• Excessive sweating (intense exercise, febrile illnesses)
• Inadequate nutrition or irregular diets
• Some kidney diseases
• Excessive alcohol consumption
• Eating disorders (anorexia, bulimia)

Electrolyte imbalances are usually temporary and the QT interval returns to normal when corrected. However, recurrent imbalances can lead to dangerous rhythm disorders, especially in people with genetic predisposition.

Other medical conditions. Some diseases and conditions can also prolong the QT interval:

• Underactive thyroid gland (hypothyroidism)
• Excessive weight (obesity)
• Heart diseases (heart failure, post-heart attack)
• Neurological conditions such as brain hemorrhage or stroke
• HIV infection
• Connective tissue diseases

With treatment of these conditions, QT prolongation usually improves as well. However, if the underlying condition continues, QT prolongation may be permanent and require treatment.

Complications

If not properly treated, long QT syndrome can lead to serious and life-threatening complications. Most of these complications are related to the heart developing dangerous rhythm disorders. With regular follow-up and appropriate treatment, these risks can be greatly reduced.

• Torsade de pointes. This is a dangerous rhythm disorder specific to long QT syndrome. In French it means "twisting of the points" and comes from the heart beats appearing to rotate around a point on the ECG. During this rhythm disorder, the heart reaches a very high rate of 200-300 beats per minute and cannot pump blood effectively. Torsade de pointes is usually brief and ends on its own. However, if it lasts long or repeats frequently, it can turn into ventricular fibrillation.
• Ventricular fibrillation. This is a very dangerous rhythm disorder in which the lower chambers of the heart (ventricles) contract irregularly and ineffectively, as if quivering. In this condition, the heart cannot pump blood and oxygen does not reach the body. Ventricular fibrillation can lead to brain damage and death within minutes. It must be stopped urgently with electrical shock (defibrillation).
• Sudden cardiac arrest. The result of ventricular fibrillation continuing without emergency intervention is that the heart stops completely. Sudden cardiac arrest leads to death within minutes if not treated.
• Fainting and fall-related injuries. Recurrent fainting episodes can lead to serious injuries as a result of falling. Injuries such as head trauma, bone fractures, and internal bleeding can occur during fainting.
• Psychological effects. Long QT syndrome diagnosis and carrying the constant risk of rhythm disorder can cause anxiety, depression, and a decline in quality of life.

Diagnosis

Long QT syndrome diagnosis is made by combining the patient's history, family history, physical examination, and various tests. The main purpose of the diagnostic process is to determine how prolonged the QT interval is, identify the genetic type, and assess the risk of rhythm disorder.

The diagnostic process usually includes:

Detailed patient history and family history is the most important step in diagnosis.

Your doctor will ask you the following questions:

• Have you ever fainted before?
• When, where, and what were you doing when the fainting occurred?
• Did you feel any warning signs before fainting? (dizziness, palpitations, dimming of vision)
• Have you ever had a seizure?
• Have you been diagnosed with epilepsy?
• Have you ever felt palpitations?
• When do palpitations occur? (during exercise, at rest, during sleep)
• Are there medications or herbal supplements you are using?
• Is there a family history of unexplained sudden death, drowning, or cardiac arrest at a young age (under 50)?
• Is there anyone in your family with long QT syndrome, fainting, or seizure history?

Family history, especially if there are sudden deaths at a young age, is a strong clue for long QT syndrome. Unexplained traffic accidents or drowning cases in the family may actually have been due to sudden cardiac arrest.

Electrocardiogram (ECG). This is the basic test in the diagnosis of long QT syndrome. ECG is a quick and painless test that records the electrical activity of the heart. Small adhesive electrodes are placed on your chest, arms, and legs, and these electrodes are connected to the ECG device with cables. The device prints or displays your heart's electrical signals on paper or a computer screen.

The "QT interval" is measured on the ECG. This is the time from the beginning of the heart's contraction to the completion of re-electrically charging to prepare for the next beat. This time is corrected according to heart rate and expressed as "corrected QT" (QTc). Normal QTc duration is below 450 milliseconds in men and 460 milliseconds in women. Durations above these values raise suspicion for long QT syndrome. Values above 500 milliseconds significantly increase the risk of rhythm disorder.

However, ECG may be normal in some people with long QT syndrome. Therefore, if suspicion continues, additional tests may need to be done.

Exercise test (Stress ECG). In some long QT syndrome types (especially LQT1), the QT interval prolongs even more during exercise compared to normal or does not shorten sufficiently. In this test, your ECG is recorded while you exercise on a treadmill or bicycle ergometer. The QT interval is measured during exercise and the recovery period. Continuation of QT prolongation especially in the first minutes of the recovery period is a typical finding for long QT syndrome.

Holter monitor. This is a portable ECG device worn for 24-48 hours. It records your heart rhythm during your daily activities. It is especially used to evaluate the variation of the QT interval throughout the day in people with symptoms but normal standard ECG. It also gives a chance to catch temporary rhythm disorders.

Drug or drug-free provocation tests. In some centers, adrenaline (epinephrine) or other stimulant medications are given to people suspected of having long QT syndrome but whose diagnosis has not been confirmed, and how the QT interval changes is observed. These tests can help with diagnosis especially when genetic tests are limited. However, these tests should be done carefully in centers with emergency intervention capability due to the risk of triggering a rhythm disorder.

Genetic test. The most definitive method in the diagnosis of long QT syndrome is genetic testing. From a blood sample, mutations in genes causing long QT syndrome are investigated. Genetic testing has three important benefits:

• Confirms the diagnosis and determines which genetic type it is (LQT1, LQT2, LQT3, etc.). This is important in treatment planning and determining which triggers should be avoided.
• Enables family screening. Family members carrying the mutation can be identified and preventive measures can be taken.
• Family members not carrying the mutation are spared from unnecessary follow-up and worry.

However, genetic tests have limitations. Some patients may have no mutation found in known genes. Also, interpretation of genetic test results requires expertise and should be done with genetic counseling.

Family screening. When long QT syndrome is detected in a person, testing of first-degree relatives (mother, father, siblings, children) is also recommended. Family screening usually starts with ECG and is confirmed with genetic testing. This way, family members who have not yet shown symptoms but are at risk can be identified and preventive measures can be taken.

Treatment

The purpose of long QT syndrome treatment is to prevent dangerous rhythm disorders, stop fainting episodes, and minimize the risk of sudden cardiac arrest. Treatment is personalized and determined according to the patient's age, genetic type, severity of symptoms, and risk factors.

Treatment options include:

Lifestyle changes and avoiding triggers. This is one of the cornerstones of treatment. Situations to avoid vary depending on which genetic type you have:

• For LQT1 type: Exercise, especially swimming, is an important trigger. Sudden cold water contact to the chest and exertion during swimming can trigger rhythm disorder. For this reason, swimming is an activity that requires caution. Also, intense exercises such as running, basketball, and football should be avoided or done under doctor's supervision.
• For LQT2 type: Sudden loud sounds (alarm clock, phone, doorbell, siren, thunder) are important triggers. It is important to remove phones and alarm clocks from the bedroom, silence phones at night, and avoid loud environments. Also, sudden emotional arousals (fear, anger, excitement) can be triggers.
• For LQT3 type: Symptoms usually occur during rest or sleep. For this reason, care should be taken during nighttime hours. Having a companion in the bedroom or using audio warning systems such as baby monitors may be recommended.

Common measures for all types:

• Avoiding QT-prolonging medications (do not use new medication without consulting your doctor)
• Avoiding situations that can lead to electrolyte imbalance (excessive sweating, diarrhea, vomiting)
• Paying attention to adequate fluid and mineral intake
• Staying away from stress as much as possible

Beta blocker medications. This is the most commonly used medication group in long QT syndrome treatment. These medications block the effect of adrenaline on the heart, slow the heart rate, and reduce the risk of developing rhythm disorder. They are especially effective in LQT1 and LQT2 types. The most commonly used beta blockers are nadolol, propranolol, and metoprolol.

Beta blockers are recommended for all patients with symptoms and some symptom-free high-risk people. The medication is used regularly, usually lifelong. Regular use is very important for the medication to be effective. Beta blockers may have side effects such as fatigue, weakness, cold hands and feet, and sleep problems. These side effects are usually temporary or can be improved with dose adjustment.

Mexiletine and other medications. In LQT3 type, a medication called mexiletine, which is a sodium channel blocker, can be used. This medication reduces the risk of rhythm disorder by shortening the QT interval. Some additional medications (potassium supplements, spironolactone, etc.) can also be used in other types. However, these medications are not as widely used as beta blockers and are usually considered as a second option.

Pacemaker. In some long QT syndrome patients, especially in LQT3 type or those whose heart rate is very slow despite beta blockers, a pacemaker may be needed. The pacemaker activates when the heart slows down too much and prevents the heart from falling below a certain rate. This way, rhythm disorders that occur especially during rest or sleep can be prevented. The pacemaker is usually not used alone but together with beta blocker treatment.

Implantable cardioverter defibrillator (ICD). This is the most effective protective method in high-risk patients. The ICD is a small device placed subcutaneously in the chest area, below the collarbone. The device continuously monitors heart rhythm and when it detects a dangerous rhythm disorder (torsade de pointes or ventricular fibrillation), it automatically delivers an electrical shock to restore normal rhythm.

ICD may be recommended in the following situations:

• Those who have had sudden cardiac arrest before
• Those with recurrent fainting episodes despite beta blocker treatment
• Those with very long QT interval (above 500 milliseconds)
• Some high-risk genetic types
• Those with a family history of sudden death at a young age

ICD is a life-saving device but has some disadvantages. Its placement requires a small surgical procedure, it needs to be replaced when the battery life expires (usually every 5-10 years), it can deliver unnecessary shocks, and it can bring restrictions on some activities such as sports. However, for most patients, the benefits far outweigh the risks.

Left sympathetic denervation. In this surgical procedure, some nerve fibers belonging to the heart's sympathetic nervous system are cut. These nerves cause the heart to accelerate during stress and exercise. With this procedure, the stimulating effect of adrenaline on the heart is reduced, lowering the risk of rhythm disorder. The procedure is usually done from the left side of the chest with small incisions (thoracoscopic surgery). It can be considered in patients with recurrent fainting despite beta blockers, those with ICD who receive frequent shocks, or those who cannot have ICD placed such as small children.

Living with Long QT Syndrome

After being diagnosed with long QT syndrome, you may need to make some adjustments in your life. However, with proper treatment and precautions, most patients can live a normal and productive life. Here are things you should pay attention to when living with long QT syndrome:

Use your medications regularly. If you are using beta blockers or other medications, it is very important to take them regularly as your doctor recommends. Never stop your medications without consulting your doctor. Using your medications regularly greatly reduces the risk of rhythm disorder. Make it a habit to take your medications at the same time every day. Have enough medication when traveling and carry your medications with you.

Recognize and avoid your triggers. Learn which factors pose a risk for you. Discuss with your doctor what you need to pay attention to according to your genetic type.

For example:

• If you have a type triggered by exercise, avoid risky activities such as swimming or definitely do them under supervision.
• If you have a sound-sensitive type, remove phones and alarm clocks from your bedroom, silence your phone at night.
• If you know that sudden emotional reactions are triggers, learn stress management techniques and get professional support when needed.

Consult your doctor before using new medication. The list of QT-prolonging medications is long and constantly updated. Before using any prescription or over-the-counter medication, herbal supplement, or vitamin, definitely consult your doctor or pharmacist. Definitely inform all healthcare professionals, including dentists, that you have long QT syndrome. It may be useful to carry a card or bracelet stating the medications you use and that you have long QT syndrome.

Do not miss your regular doctor checkups. Long QT syndrome is a condition that requires lifelong follow-up. You are recommended to go to a cardiology checkup at least once a year. At checkups, an ECG will be taken, the effectiveness of your medications will be evaluated, and if necessary, dose adjustment will be made. If you have an ICD, regular checks of the device will be done and battery life will be evaluated.

Consult your doctor about exercise and physical activity. Exercise recommendations in people with long QT syndrome vary according to genetic type and risk level. While some patients can do light-moderate exercise, some need to avoid intense exercise. Swimming especially carries high risk for LQT1 type. Competitive sports are generally not recommended. However, activities such as walking, light jogging, and yoga may be safe for most patients. Definitely consult your doctor before starting an exercise program.

Family planning and pregnancy. Women with long QT syndrome should definitely consult with cardiology and a gynecologist who is an expert on high-risk pregnancy before planning pregnancy. The risk of rhythm disorder may increase during pregnancy and the postpartum period. The safety of medications used during pregnancy should be evaluated and medication changes should be made if necessary. Close follow-up may be needed during and after delivery. It is important that the baby also be tested due to the risk of genetic transmission.

Inform your relatives. Give information about your condition to your family, close friends, and coworkers. Teach them what they should do in case of fainting or cardiac arrest.

Have your family members screened. Long QT syndrome is a genetically inherited disease. After you are diagnosed, it is very important that your first-degree relatives (mother, father, siblings, children) also be tested. Even if there are no symptoms yet in your family members, they may be at risk. With early diagnosis and treatment, they can also be protected from the risk of sudden cardiac arrest. Discuss this topic with your family gently but firmly and ask for help from your doctor if necessary.

Get psychological support. Living with a chronic disease, especially dealing with a condition that carries a risk of sudden death, can be difficult. You may experience psychological problems such as anxiety, depression, and sleep problems. Share these feelings with your doctor. If necessary, get support from a psychologist or psychiatrist. Also, patient support groups can be very beneficial for sharing experiences with people experiencing similar situations.

Preparing for Your Appointment

Preparing before going to your doctor's appointment makes the visit more productive and helps you ask all your questions.

What you can do:

• Note your symptoms. If you have complaints such as fainting, palpitations, or dizziness, note in detail when they started, how often they occur, how long they last, and in what situations they occur (during exercise, with a sudden sound, during emotional stress, at rest).
• Research your family history. Find out if there is a family history of sudden death at a young age (under 50), unexplained traffic accident, drowning, or cardiac arrest. Also note if there are people in the family diagnosed with fainting, seizures, or epilepsy.
• List all medications you use. Make a list of all products you use including prescription medications, over-the-counter medications, herbal supplements, vitamins, and birth control pills. Write down the name, dose, and how often you use each one.
• Collect your past medical records. If you have previously taken ECGs, echocardiography reports, or hospital admissions, take these to the doctor.
• Write down your questions in advance. Prepare a list in advance so you don't forget the questions you want to ask the doctor. Organize your questions in order of importance so you can ask the most important ones first if time runs out.

Questions you can ask your doctor:

• Is the diagnosis of long QT syndrome certain in my case?
• Which genetic type do I have? (LQT1, LQT2, LQT3, etc.)
• Which triggers pose a risk for me?
• Which medications should I avoid? Can you give me a list of safe medications?
• Which treatment is most suitable for me? Is medication enough or is ICD necessary?
• How long will I use my medications? What are the side effects?
• Can I exercise? Which sports are safe, which are risky?
• I am planning pregnancy, what should I pay attention to?
• Do my family members need to be tested?
• How often should I have checkups?
• What should I pay attention to in my daily life? Can I drive?
• What should I do in an emergency? Is there a card or bracelet I should carry?

Your doctor may ask you:

• Have you ever fainted before? How many times has fainting occurred and in what situations?
• Did you feel any symptoms before fainting? (dizziness, palpitations, dimming of vision)
• Have you ever had a seizure? Have you been diagnosed with epilepsy?
• Have you ever felt palpitations? When do palpitations occur? (during exercise, at rest, during sleep)
• Is there a family history of sudden death, drowning, or cardiac arrest at a young age?
• Are there medications or herbal supplements you are using?
• Have you had heart disease, rhythm disorder, or another health problem before?
• Have you had any surgery recently?